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The aim of this review was to assess the effectiveness, safety, and cost of sacral nerve stimulation (SNS) to treat urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence.
Urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence are prevalent, yet rarely discussed, conditions. They are rarely discussed because patients may be uncomfortable disclosing their symptoms to a health professional or may be unaware that there are treatment options for these conditions. Briefly, urge incontinence is an involuntary loss of urine upon a sudden urge. Urgency-frequency is an uncontrollable urge to void, which results in frequent, small-volume voids. People with urgency-frequency may or may not also experience chronic pelvic pain. Urinary retention refers to the inability to void despite having the urge to void. It can be caused by a hypocontractile detrusor (weak or no bladder muscle contraction) or obstruction due to urethral overactivity. Fecal incontinence is a loss of voluntary bowel control.
The prevalence of urge incontinence, urgency-frequency, and urinary retention in the general population is 3.3% to 8.2%, and the prevalence of fecal incontinence is 1.4% to 1.9%. About three-quarters of these people will be successfully treated by behaviour and/or drug therapy. For those who do not respond to these therapies, the options for treatment are management with diapers or pads, or surgery. The surgical procedures are generally quite invasive, permanent, and are associated with complications. Pads and/or diapers are used throughout the course of treatment as different therapies are tried. Patients who respond successfully to treatment may still require pads or diapers, but to a lesser extent.
Sacral nerve stimulation is a procedure where a small device attached to an electrode is implanted in the abdomen or buttock to stimulate the sacral nerves in an attempt to manage urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence. The device was originally developed to manage urinary urge incontinence; however, it has also been used in patients with urgency-frequency, urinary retention, and fecal incontinence. SNS is intended for patients who are refractory to behaviour, drug, and/or interventional therapy.
There are 2 phases in the SNS process: first, patients must undergo a test stimulation phase to determine if they respond to sacral nerve stimulation. If there is a 50% or greater improvement in voiding function, then the patient is considered a candidate for the next phase, implantation.
The standard Medical Advisory Secretariat search strategy was used to locate international health technology assessments and English-language journal articles published from 2000 to November 2004. The Medical Advisory Secretariat also conducted Internet searches of Medscape (1) and the manufacturer’s website (2) to identify product information and recent reports on trials that were unpublished but that were presented at international conferences. In addition, the Web site Current Controlled Trials (3) was searched for ongoing randomized controlled trials (RCTs) investigating the role of sacral nerve stimulation in the management of voiding conditions.
Four health technology assessments were found that reviewed SNS in patients with urge incontinence, urgency-frequency, and/or urinary retention. One assessment was found that reviewed SNS in patients with fecal incontinence. The assessments consistently reported that SNS was an effective technology in managing these voiding conditions in patients who did not respond to drug or behaviour therapy. They also reported that there was a substantial complication profile associated with SNS. Complication rates ranged from 33% to 50%. However, none of the assessments reported that they found any incidences of permanent injury or death associated with the device.
The health technology assessments for urge incontinence, urgency-frequency, and urinary retention included (RCTs (level 2) as their primary source of evidence for their conclusions. The assessment of fecal incontinence based its conclusions on evidence from case series (level 4). Because there was level 2 data available for the use of SNS in patients with urinary conditions, the Medical Advisory Secretariat chose to review thoroughly the RCTs included in the assessments and search for publications since the assessments were released. However, for the health technology assessment for fecal incontinence, which contained only level 4 evidence, the Medical Advisory Secretariat searched for studies on SNS and fecal incontinence that were published since that assessment was released.
Two RCTs were identified that compared SNS to no treatment in patients with refractory urge incontinence. Both RCTs reported significant improvements (> 50% improvement in voiding function) in the SNS group for number of incontinence episodes per day, number of pads used per day, and severity of incontinence episodes.
One RCT was identified that compared SNS to no treatment in patients with refractory urgency-frequency. The RCT reported significant improvements in urgency-frequency symptoms in the SNS group (average volume per void, detrusor pressure). In addition to the RCT, 1 retrospective review and 2 prospective case series were identified that measured pelvic pain associated with urgency-frequency in patients who underwent SNS. All 3 studies reported a significant decrease in pain at median follow-up.
One RCT was identified that compared SNS to no treatment in patients with refractory urinary retention. The RCT reported significant improvements in urinary retention in the SNS group compared to the control group for number of catheterizations required and number of voids per day. In addition to this RCT, 1 case series was also identified investigating SNS in women with urinary retention. This study also found that there were significant improvements in urinary retention after the women had received the SNS implants.
Three case series were identified that investigated the role of SNS in patients with fecal incontinence. All 3 reported significant improvements in fecal incontinence symptoms (number of incontinent episodes per week) after the patients received the SNS implants.
None of the studies identified followed patients until the point of battery failure. Of the 6 studies identified describing the long-term follow-up of patients with SNS, follow-up periods ranged from 1.5 years to over 5 years. None of the long-term follow-up studies included patients with fecal incontinence. All of the studies reported that most of the patients who had SNS had at least a 50% improvement in voiding function (range 58%–77%). These studies also reported the number of patients who had their device explanted in the follow-up period. The rates of explantation ranged from 12% to 21%.
A 33% surgical revision rate was reported in an analysis of the safety of 3 RCTs comparing SNS to no treatment in patients with urge incontinence, urgency-frequency, or urinary retention. The most commonly reported adverse effects were pain at the implant site and lead migration. Despite the high rate of surgical revision, there were no reports of permanent injury or death in any of the studies or health technology assessments identified. Additionally, patients consistently said that they would recommend the procedure to a friend or family member.
One health technology assessment and 1 abstract were found that investigated the costing factors pertinent to SNS. The authors of this assessment did their own “indicative analysis” and found that SNS was not more cost-effective than using incontinence supplies. However, the assessment did not account for quality of life. Conversely, the authors of the abstract found that SNS was more cost-effective than incontinence supplies alone; however, they noted that in the first year after SNS, it is much more expensive than only incontinence supplies. This is owing to the cost of the procedure, and the adjustments required to make the device most effective. They also noted the positive effects that SNS had on quality of life.
In summary, there is level 2 evidence to support the effectiveness of SNS to treat people with urge incontinence, urgency-frequency, or urinary retention. There is level 4 evidence to support the effectiveness of SNS to treat people with fecal incontinence.
To qualify for SNS, people must meet the following criteria:
Patients with stress incontinence, urinary retention due to obstruction and neurogenic conditions (such as diabetes with peripheral nerve involvement) are ineligible for sacral nerve stimulation.
Physicians will need to learn how to use the InterStim System for Urinary Control. Requirements for training include these:
The objective of this review was to systematically review the evidence of the effectiveness, safety, and costing of sacral nerve stimulation (SNS) to treat urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence.
This report focuses on the management of patients with urinary urge incontinence, urgency-frequency, urinary retention, or fecal incontinence. Urge incontinence is an involuntary loss of urine upon a sudden urge. Urgency-frequency is an uncontrollable urge to void, resulting in frequent, small volume voids. Urgency-frequency is often associated with interstitial cystitis and chronic pelvic pain. Urinary retention refers to the inability to void despite having the urge to void, it can be caused by a hypocontractile detrusor (weak or no bladder muscle contraction) or obstruction due to urethral overactivity. Fecal incontinence is a loss of voluntary control of the passage of liquid or solid stool. There is some evidence to suggest that people with a history of sexual abuse are more likely to suffer from urinary and fecal incontinence than the general population. (4;5)
Urinary incontinence is often misinterpreted as a natural part of aging; however, this is not the case.. (6) Incontinence can be temporary, due to conditions such as urinary tract infections, vaginal infections, constipation; or due to an adverse effect from medications. Alternatively, incontinence can be chronic and affect patients indefinitely. Urinary incontinence is a symptom, not a disease. There are 3 types of urinary incontinence:
A person may have a combination of the 3 types of incontinence. This is called mixed incontinence. The Canadian Continence Foundation (7) estimates that 25% of women over 40 years and 15% of men and women over 60 years have some type of incontinence.
The social implications of urinary incontinence include low self-esteem, restriction of social and sexual activities, and depression. Furthermore, urinary incontinence is often an important factor in deciding when to place elderly people in nursing homes. This has economic implications.
This report focuses on urge incontinence, because the device used during SNS is designed to manage urge incontinence only. There are 3 broad categories of urge incontinence (8):
It is important to note that SNS is indicated for people with non-neurogenic urge incontinence.
Urgency-frequency is characterized by the uncontrollable urge to urinate, resulting in frequent small-volume voids. One symptom of urgency-frequency is the feeling of not being able to void completely, which may or may not be associated with chronic pelvic pain. People who have urgency-frequency may void as often as every half hour and more than 4 times per night. This frequency can substantially interfere with people’s quality of life and daily activities. For example, people cannot drive long distances without stopping, or attend meetings, or socialize normally. Sleep patterns are disrupted due to nocturia To cope, some people will limit the consumption of liquids and dehydrate themselves. People will also use diapers or pads to prevent accidental wetting from leaking through their clothing.
People with urinary retention are diagnosed as having complete retention (the inability to initiate a void), or partial retention (> 50 mL of residual urine in bladder after voiding). They may or may not have the sensation of fullness (i.e., feel the need to void). If they cannot sense bladder fullness, they are likely to suffer from overflow incontinence (constant leaking). The potential causes of urinary retention include weak or no bladder muscle contraction, obstruction of urethra (due to cancer, benign prostatic hypertrophy, or urethral overactivity), pelvic floor dysfunction, or an adverse effect of drug therapy. Most patients who receive SNS for urinary retention have urinary retention due to pelvic floor dysfunction (Personal communication, February 2005). Those who have urinary retention due to an obstruction will not benefit from SNS; therefore, they are not candidates for the procedure.
Urinary retention has several effects, including psychosocial implications that affect quality of life and self-esteem. There are also secondary health conditions due to increased abdominal pressure (resulting in hemorrhoids, urinary reflux, and/or kidney infection); poor fluid management; and repeated catheterizations (resulting in urinary tract infections, kidney stones, and impaired renal function).
Fecal incontinence refers to incontinence of flatus as well as the involuntary loss of stool. (9) Fecal incontinence can be passive or active. Passive fecal incontinence is when the person is unaware of the incontinence (i.e., has no urge). Active incontinence refers to a situation where the person is aware of the incontinence; however, he or she is unable to prevent it. Fecal incontinence may be caused by damage to the anal sphincter mechanism (through direct trauma or damage to the nerve supply), idiopathic degeneration of the sphincter, spinal injury, or other neurological conditions (e.g., multiple sclerosis). Obstetric trauma is the most important etiological factor in non-neurogenic fecal incontinence. (10) A study (11) investigating fecal incontinence found a significant association between fecal incontinence and episiotomy (P < .01), forceps delivery (P < .01), perineal tears (P < .01) and hysterectomy (P < .05).
Generally, there are 4 broad areas of treatment for urge incontinence: behaviour modification, drug therapy, interventional therapy (including external electrical stimulation or intravesical electrical stimulation), and surgery. Diapers or pads are used throughout treatment and may be used in conjunction with the treatments. Patients who are treated successfully may still require diapers, but to a lesser extent.
Behaviour modification therapies include diet modification (avoiding caffeine, alcohol, dairy products and spices), toileting assistance (scheduled voiding), bladder training or retraining (to increase voiding volume and interval between voids), pelvic muscle rehabilitation (Kegel exercises), and biofeedback. Behaviour modification is sometimes overlooked as the first treatment option for patients with urge incontinence. (12) In a study (13) assessing the treatment of 372 patients with urge incontinence, drug therapy was the first-line treatment for 50% of the patients, and only 13% were treated with behaviour therapy first.
The evidence supporting or refuting the use of behaviour therapy to manage urge incontinence is limited. Four systematic reviews (12;14-16) have been identified that investigated behaviour therapy to manage urinary incontinence. A Cochrane review (16) of bladder training in adults with urinary incontinence reported that the studies that investigated bladder training were of variable quality and reported various outcome measures, which makes comparing the studies difficult. Wallace et al. (16) concluded that bladder training seemed effective in the management of urinary incontinence; however, they could not comment on if bladder training was better than other available treatments.
A Cochrane review by Haye-Smith et al. (14) [AU: The authors’ names in text and in the citation do not match.] investigating behaviour therapy in people with urinary incontinence specifically focused on pelvic floor muscle exercises in women. They reported that pelvic floor exercises were effective to manage stress and mixed incontinence; however, the evidence supporting or refuting the use of pelvic floor exercises in women with urge incontinence was unclear. Similar to the conclusions by Wallace et al., Hay-Smith et al. reported that the studies included in their review reported various outcomes with little consistency between studies.
The authors of a systematic review (12) of randomized controlled trials (RCTs) on conservative management options for urge incontinence concluded that there was insufficient evidence to indicate that behaviour therapy, or drug therapy, or external electrical stimulation was the superior treatment. Another systematic review (15) that compared behaviour therapy with drug therapy in older patients (aged at least 55 years) with urinary incontinence (including stress, urge, and mixed incontinence) reported that drug therapy was less effective than behaviour therapy. They based their conclusion on 8 studies: 4 RCTs and 4 crossover studies. Three of the studies found that biofeedback significantly reduced the number of urge incontinence episodes compared with either drugs or placebo (P < .05). The other studies did not find a significant difference between treatments. None of the studies reported that drug therapy was significantly better than biofeedback.
Based on the results of these systematic reviews, it is not possible to understand fully the role of behaviour therapy in the management of urinary incontinence. Behaviour therapy seems to be effective in some groups of patients, but not in others. The success of a behaviour therapy intervention depends largely on the infrastructure supporting the intervention (Personal communication, February 2005). In other words, behaviour therapy requires resources such as staff (i.e. administrative staff, nurse continence advisors and other specialists) and clinic space in order to effectively teach patients the behaviours. The underlying factors that predict a patient’s success with behaviour therapy still need to be identified.
If behaviour modification is unsuccessful, drug therapy is prescribed. (13) There are 4 general types of drugs used to treat patients with urinary urge incontinence:
(See also Table 1, which lists some of the drugs used for managing urge incontinence and their possible adverse effects.)
There have been some relatively recent advances in the development of drug therapies for managing urge incontinence. Two drugs, tolterodine and oxybutynin, have “long-acting” or “extended release” formulations. With these, a patient needs to take only 1 pill per day, and there may be fewer adverse effects because the long-acting formulations are more stable than the original versions (Personal communication, February 2005). Dry mouth is the most common side effect in patients taking anticholinergics.
In a systematic review of tolterodine, Garely and Burrows (17) reported the results of a RCT that compared tolterodine (original version) to a placebo. They found that 35% of 986 patients in the tolterodine group reported dry mouth compared with 10% of the 683 patients in the placebo group. Garely and Burrows also reported results of a RCT that compared tolterodine long acting (Detrol LA) to a placebo and found that 24% of 505 patients in the treatment group reported dry mouth compared with 8% of the 507 patients in the placebo group. Based on these results, it seems that the new long-acting formulation may be associated with fewer adverse effects than the original; however, it is important to recognize that a trial comparing original tolterodine to tolterodine long-acting is needed for confirmation.
Before the release of these new drugs, poor compliance rates had been reported among patients using drug therapy to manage the symptoms of urinary urge incontinence because of the adverse effects of the drugs. The adverse effects reported included dry mouth, blurred vision, dry eyes, decreased sweating, and gastrointestinal effects. (18)
In 1999, Desgagne and LeLorier (18) did a retrospective study on the use of oxybutynin and flavoxate among Quebec residents aged 65 years or older (N = 6,690). They found that only 11.4% of the patients who were prescribed oxybutynin and 5.7% of the patients prescribed flavoxate were still taking the drug at 6 months. Oxybutynin has been associated with a higher adverse effect profile than tolterodine, (17;19) and according to an Ontario urologist who treats patients who have urge incontinence, flavoxate is rarely prescribed as first-line drug therapy for urge incontinence (Personal communication, February 2005). Harvey et al. (19) did a meta-analysis to compare tolterodine to oxybutynin (original versions) in patients with urge incontinence. They found oxybutynin was significantly more efficacious than tolterodine (weighted mean difference 0.41; 95% confidence interval [CI] 0.04–0.77, no P-value reported); however, tolterodine was associated with fewer adverse effects and lower drop-out rates. In an RCT comparing tolterodine (original version) to oxybutynin extended-release (Ditropan XL), Appell et al. (20) reported that oxybutynin extended-release was significantly more effective than tolterodine, and both drugs had similar toxicity profiles.
Herbison et al. (21) did a systematic review that compared anticholinergic drugs with a placebo in patients with urge incontinence found that there was an improvement in voiding function in patients receiving anticholinergic drugs (P < .0001), but that they also suffered from substantial adverse effects. Herbison et al. noted that patients receiving the anticholinergic drugs suffered from worse dry mouth (P < .0001). They concluded that the difference in effectiveness between the treatment and control group may not be clinically significant when combined with the adverse effects of the anticholinergic drugs. It is important to note that Herbison et al. included studies reporting on various anticholinergic drugs in their systematic review, and they included studies from 1978 in their meta-analyses of effectiveness. Drug technology has changed substantially over the past 25 years, and as mentioned previously, drugs for urinary incontinence have changed substantially over the past few years. The results of this study would be more intriguing if they had limited the scope of drugs included in their analysis and had limited the search strategy to studies less than 5 years old.
A 2004 systematic review by Siddiqui et al. (22) reported that 3 multicentre RCTs that compared oxybutynin with placebo treatment found that 28% to 51% of patients receiving oxybutynin achieved continence. Thus, between 49% and 72% failed to respond to the drug and required alternate treatments. Thus, drug therapy is effective and safe for many patients with urge incontinence, and with advances in drug technology, ideally the adverse effects of these drugs will continue to decline. Nonetheless, there is still a subset of patients for whom drug therapy does not work to control their urge incontinence.
If drug therapy is ineffective, interventional therapies are the next option. Interventional therapies for urge incontinence include external electrical stimulation, which stimulates the pelvic floor muscles, and intravesical electrical stimulation, which stimulates the inside of the bladder wall in an attempt to control micturition. Little information is available on the effectiveness of these therapies. It is important to recognize that behaviour, drug, and interventional therapies may be used together, and that the therapies are not necessarily independent of one another.
If behavioural, drug, and interventional therapies are all unsuccessful, then surgery is the next alternative. Possible surgical interventions include these:
These surgeries are considered a final attempt to manage urge incontinence, because they are invasive and irreversible. It is important to note that even though surgery may be able to control the voiding dysfunction, it may not lead to an overall improvement in quality of life, because of the associated adverse effects and complications (Personal communication, December 2004). The surgical revision rate for patients with artificial urinary sphincter is 50% up to 5 years after implantation. (24) Patients who fail conservative treatment and are ineligible for surgery (e.g., for various reasons, including comorbid conditions and frailty) manage their urge incontinence with diapers.
Non-surgical treatment options for patients with urgency-frequency are diet modification, drug therapy, and behavioural techniques (e.g., timed voiding, pelvic muscle exercises, and biofeedback). Hydrodistention is an interventional therapy for patients with urgency-frequency, in which the bladder is stretched with fluid. Stretching the bladder is thought to alter neurologic function, resulting in decreasing the transmission of pain. (25) In addition, stretching the bladder wall may stimulate production of bladder surface mucin, the normal protective coating of the bladder surface. Patients who experience chronic pelvic pain in association with urgency-frequency are sometimes prescribed narcotics to manage the pain. (26)
Surgical treatments for urgency-frequency include augmentation cystoplasty to increase the size of the bladder and bladder removal/urinary diversion. If non-surgical procedures do not work, and patients refuse or are ineligible to have surgery, then they manage their voiding condition by voiding frequently, using diapers or pads, and/or restricting fluids.
No drug therapies were identified that effectively treated urinary retention. However, patients who have urinary retention due to benign prostatic hypertrophy are often prescribed alpha-blockers. These relax the periurethral portion of the external urethral sphincter to relieve some obstruction. Catheterization is used to reduce the volume of residual urine. Intermittent catheterization is associated with a lower infection rate than is permanent indwelling catheterization (inserting a catheter into the bladder, where it remains). Indwelling catheterization is recommended for people who are severely impaired or terminally ill.
Surgical treatments for urinary retention include urethrolysis, the removal of an anatomic obstruction in women; transurethral prostatectomy; stent placement or sphincterectomy to treat bladder neck obstruction); and urinary diversion continent pouch or orthotopic neobladder, to increase bladder size or divert urine from the bladder.
Initially, the treatment options for fecal incontinence are diet change, antidiarrheal medication, and physical and behavioural therapy (such as pelvic floor exercises). Absorbent pads and anal plugs may also be used. Pads and diapers may be used throughout the course of treatment. If these treatments are not effective, then surgical interventions are the next option. These comprise sphincter repair, dynamic graciloplasty (transposition of the gracilis muscle [from upper leg] to the anus with the implantation of stimulating electrodes), and implantation of an artificial bowel sphincter. The most extreme management option for fecal incontinence is colostomy.
A Cochrane systematic review (27) investigated studies of drugs to manage fecal incontinence in adults. They found 11 trials that met their inclusion criteria; however, they noted that the studies included patients with diarrhea and/or fecal incontinence. Based on the results of the 11 small trials, there was little evidence indicating that drugs (antidiarrheal drugs and drugs that enhance anal sphincter tone) improved fecal incontinence.
The authors (28) of a systematic review of 14 studies evaluating the role of implanting an artifical bowel sphincter to manage fecal incontinence found that the benefit of the procedure is uncertain and associated with many potentially harmful side effects. A multisite case series (29) evaluating the safety and efficacy of implanting an artifical bowel sphincter for fecal incontinence reported 449 adverse effects among the 115 patients who had the procedure. Surgical intervention was required to manage 36% of these. Infection and erosion of the implanted artificial bowel sphincter were the complications that most frequently required surgical revision. Forty-one (36%) patients had their devices explanted. Despite the adverse events, the procedure was effective in 85% of the patients who still had the device implanted after 12 months.
In summary, if dietary changes, drug therapy, and physical and behavioural therapy are unsuccessful in the management of fecal incontinence, then the next option is invasive surgery, which is associated with considerable adverse effects. If a patient refuses or is ineligible for surgery, then the incontinence is managed with diapers.
During SNS, a device is implanted to stimulate electrically the sacral nerves in an attempt to manage voiding conditions. It is a reversible procedure, in that the device can be removed without permanent injury. The device was originally developed to manage urinary urge incontinence; however, it has also been used in patients with urgency-frequency, urinary retention, and fecal incontinence. According to Medtronic Inc. (Minneapolis, MN, United States), the manufacturer of the InterStim System for Urinary Control, the role of SNS is to manage patients who have not been treated successfully with behaviour therapy, drug therapy, or external stimulation.
The sacral nerves play an integral role in micturition (process for discharging urine), because the sacral nerves from the spinal cord control the bladder. The micturition reflex is a 2-part cycle consisting of: filling (storage) and emptying. For the reflex to function properly, 2 systems must be intact. First, the receptors and neurotransmitters must be balanced for the muscles to operate properly. Second, the neurosensory pathway along the brain, spinal cord, and bladder must be intact. The receptors in the bladder signal the sacral nerves that the bladder is full or empty. An interruption in this process causes voiding difficulties. SNS aims to correct the disruption between the nervous system and the bladder so that normal voiding can resume. By stimulating the sacral nerve with electrical pulses, the device mimics the signals required for normal micturition.
The level of nerve stimulation is determined by the amplitude (strength of the stimulation, measured in volts), the pulse width (duration of pulse, measures in microseconds), and the rate (the number of pulses per second).
There are 2 phases in the SNS process. Patients first must have a test stimulation to determine if they respond to the stimulation. If there is a 50% or more improvement in voiding function, then the patient is a candidate for the next phase, implantation. These phases are described in detail later in this section
The Medtronic InterStim System for Urinary Control is designed to stimulate the sacral nerve to control bladder function. The device creates an electrical current that flows between the negative and positive electrode lead (which is placed adjacent to a sacral nerve, most commonly S3). The electrical current requires a power source and a complete electrical circuit. These components comprise the system:
Test stimulation is the first phase. The purpose of this phase is to determine the effectiveness of the InterStim implant. During this outpatient procedure, a needle is inserted into the sacral foramen (usually S3) under local anesthesia. Once the needle is in place, the physician attempts to identify appropriate nerve stimulation responses. If nerve stimulation responses are identified, a temporary, percutaneous lead is inserted through the needle and placed near the sacral nerve. The lead is attached to an external test stimulator that attaches to the patient’s waistband. The patient wears the test stimulator for 3 to 7 days if he or she has a urinary dysfunction, and for 2 to 3 weeks if he or she has fecal incontinence. Patients must keep a voiding diary while wearing the device to track their responses to it. If they have a 50% or more improvement in symptoms during this phase, then they are eligible for the implantation phase. Between one-third and one-half of patients who undergo test stimulation are successful and proceed to the implantation phase. (30-32)
After a patient completes a successful test stimulation, he or she is considered for surgical implantation of the InterStim System. The device is implanted under general anesthesia in an operation that lasts about 2 hours. The surgeon makes 3 incisions: one on the lower back to place the lead next to the sacral nerve and anchor it, one in the lower abdomen or upper buttock to place the implant device, and one on the flank to connect the ends of the lead and extension. The lead is passed under the skin to the implant device. Patients are usually hospitalized for 1 to 2 days postoperatively. The device is programmed up to 1 week after the surgery. The physician and the patient each have control over the device. The physician has a programmer that adjust the device. Typically, it is programmed with a pulse width of 210 μsec, and a pulse rate of 10 pulses per second. The amplitude is normally set at 0.1 volts, but can be adjusted in 0.1-volt increments by the physician. (33) Patients can turn the device on or off, and can control the amplitude in a preset range defined by the physician. Some patients must turn the device off to void.
Health Canada licensed Medtronic’s InterStim System for Urinary Control in February 2002 (Class IV, licence 14962). (All medical devices are grouped into 1 of 4 classes. Class I devices present the lowest potential risk, and Class IV devices present the greatest potential risk.) Health Canada approved the device for “the management of chronic intractable (functional) disorders of the pelvis and lower urinary or intestinal tract” (Personal communication, December 2004).
In 1998, the United States Food and Drug Administration (FDA) approved Medtronic’s InterStim System for Urinary Control to treat urinary urge incontinence in patients who had failed or could not tolerate conservative treatments. Subsequently, in 1999, the FDA approved the device for the treatment of urinary retention and the symptoms of urgency-frequency in patients who had failed or could not tolerate conservative treatments. The FDA reported that about 20% of patients with urinary urge incontinence would benefit from SNS. The FDA has not approved the device for patients with fecal incontinence; however, clinical trials are underway in the United States to apply for approval for this indication.
As of January 2005, 6 health centres in 4 provinces across Canada were using Medtronic’s InterStim System for Urinary Control: Alberta, Ontario, Quebec, and Nova Scotia. On a per capita basis, Alberta is the most active province for the SNS procedure. One hospital in Ontario does SNS. It funds 12 SNS procedures per year. In January 2005, it reported that they had a waiting list of 47 people (Personal communication, January 2005).
The Toronto Western Hospital estimated that in the Metro Toronto catchment area (population about 5 million), there would be 50 new patients per year with urge incontinence, 12 new patients with urinary retention, and 20 new patients with urgency-frequency that would be identified as candidates for SNS (i.e., 80–85 SNS procedures in Metro Toronto per year) (Personal communication, December 2004).
The prevalence of urge incontinence, urgency-frequency, urinary retention, and fecal incontinence is difficult to estimate, because people with these conditions may not tell their health practitioner about their symptoms due to embarrassment, or because they don’t know there are treatment options available.
For this review, 6 studies were identified that examined the prevalence of urge incontinence (Table 2). Corcos and Schick (34) recently reported the results of a Canadian survey that assessed the prevalence of overactive bladder (OAB) and incontinence among Canadians aged 35 years or older. OAB is characterized by urinary urgency or the presence of involuntary bladder contractions, with or without urge incontinence. They reported that the prevalence of OAB was 18.1%. The prevalence of urge incontinence (or “wet” OAB) was 2.3% overall: 2.0% for men and 2.6% for women. They reported that 0.32% of the respondents had “severe wet OAB.” The prevalence of mixed OAB (wet and dry OAB) was 0.3% for men and 2.1% for women. Corcos and Schick did not report what proportion of the patients with OAB had urge incontinence that could be managed through behavioural or drug therapies (i.e., the current standard treatment for urge incontinence).
The other Canadian study on the list was done in 2004 by Iron from the Medical Advisory Secretariat (unpublished). Iron surveyed women in Ontario on a variety of issues, including incontinence (stress and urge). Iron found that, based on the results of the survey, the prevalence of urge incontinence among women in Ontario is 6.2% and increases with age.
In 2004, McGrother et al. (35) published the results of a survey in the United Kingdom on storage symptoms of the bladder. They surveyed 162,533 residents of the United Kingdom aged 40 years or older. They found that 1.5% of women and 1.0% of men voided at least once per half hour. They also reported that 5.5% of women and 5.3% of men voided at least 3 times per night. They did not report the incidence of pelvic pain in this population.
No studies were identified that reported the prevalence of chronic pelvic pain associated with urgency-frequency. Table 3 shows the prevalence of urgency-frequency according to age and gender.
It is unclear what the prevalence of chronic urinary retention is in Canada or throughout the world. Based on a study by Evans et al. (39) that investigated the prevalence and costs of long-term catheterization in patients with chronic urinary retention, they estimated that the prevalence of chronic urinary retention ranges from 0.03% to 0.07% in the general population, and is 0.5% of the population over 75 years.
Like with the other conditions described, the prevalence of fecal incontinence is difficult to estimate, because affected individuals may not consult a physician regarding the issue. Also, there are varying definitions of fecal incontinence. For the purposes of this assessment, fecal incontinence is defined as 1 or more incontinence episodes per week. This definition was chosen because this is the eligibility criterion specified in the studies (described further) investigating SNS in patients with fecal incontinence.
Three studies were found that reported prevalence for fecal incontinence using the definition above. A cross-sectional study by Perry et al. (40) of residents aged over 40 years in the United Kingdom found that among the 10,116 respondents to their survey, 1.4% reported fecal incontinence. Perry et al. also reported that 52% of the patients with fecal incontinence said their incontinence had an important impact on their quality of life. The prevalence of incontinence increased with age, but did not differ by sex. Lam et al. (11) surveyed 955 Australians regarding urinary and fecal incontinence. They reported that 1.8% of the population suffered from fecal incontinence. The other study was by Walter et al., (41) who surveyed 2000 Swedes on their bowel habits. They reported that 1.9% of the population had fecal incontinence. Thus, the prevalence of fecal incontinence across the 3 studies was relatively consistent, ranging from 1.4% to 1.9%.
The Medical Advisory Secretariat identified 5 health technology assessments (8;10;42-44) on the role of SNS in the management of urge incontinence, urgency-frequency, urinary retention, or fecal incontinence (Table 4). One of the assessments focused specifically on fecal incontinence. (10) The others described SNS in the management of urinary dysfunctions.
Systematic review for the efficacy and safety of sacral nerve stimulation for faecal incontinence
The National Institute for Clinical Excellence (NICE) (10) identified 7 prospective case series (1 unpublished, 2 non-English–language) and 1 double-blind crossover trial (N = 2) that met the inclusion criteria.
Among the 6 of the 7 case series, 266 patients underwent test stimulation, and 149 (56%) of those patients had the implant procedure to manage their fecal incontinence. The main eligibility criterion for each of the 6 studies was that patients had to have failed conservative therapy. Among the 149 patients who had the SNS device implanted, there were 18 adverse events. Three patients (from the same centre) had infections at the site of the implantation, 8 leads were dislodged in 7 patients, 6 patients complained of pain, and 1 patient had superficial wound dehiscence that healed uneventfully.
The authors concluded that there are several adverse effects (all manageable) associated with SNS for the treatment of fecal incontinence, and that there are limited data on the long-term effectiveness and safety of SNS. NICE supports the use SNS for fecal incontinence provided that “the normal arrangements are in place for consent, audit and clinical governance.”
Systematic review for the efficacy and safety of sacral nerve stimulation for urinary urge incontinence and urgency-frequency
This health technology assessment by NICE National Institute for Clinical Excellence, 2004 (42) described the use of SNS for patients with urge incontinence or urgency-frequency. One RCT was included in the assessment. It was by Weil et al. (45) and compared SNS to no treatment in patients with refractory urge incontinence. They reported that SNS was an effective treatment for managing urge incontinence. This RCT will be described in more detail later in this report.
NICE concluded that the risk of patient harm was probably low, but that there were no data on the long-term effects of the device. They recommended more long-term studies to determine the long-term effectiveness, complications, and battery life. They also noted that hospital staff required adequate training and support to treat patients effectively with refractory urge incontinence.
In 2004, NICE released an Interventional Procedure Guidance relating to the evidence in its assessments. It stated that NICE supports the use of SNS for urge incontinence and urgency-frequency provided that “the normal arrangements are in place for consent, audit and clinical governance.” (46)
Sacral nerve stimulation for treatment of urge incontinence
Australian Safety and Efficacy Register of New Interventional Procedures–Surgical (ASERNIP–S) (43) released a rapid review in the same year as the NICE assessment. Both of the publications were similar in terms of their literature searches (including sources searched and that both searched up until October 2002) and the number of eligible studies identified. However, because the ASERNIP-S publication was a rapid review, it had substantially fewer details than did the NICE assessment. Nonetheless, both reached similar conclusions – that SNS seems to manage chronic urge incontinence effectively, but that there are substantial surgical revision and complication rates associated with it.
Sacral nerve stimulation for refractory urinary urge incontinence or urinary retention
The Medical Services Advisory Committee in Australia (MSAC) (44) published a health technology assessment on SNS for refractory urge incontinence or urinary retention in 2000. It included studies investigating SNS in patients with refractory urge incontinence or urinary retention. Their assessment was based primarily on 2 RCTs: one by Schmidt et al. (32) comparing SNS to no treatment in patients with refractory urge incontinence and an abstract of an RCT by Grunewald et al. (47) comparing SNS to no treatment in patients with refractory urinary retention. (The full study was published in 2001 by Jonas et al. (31))
The MSAC reported that both of the RCTs had “methodological deficiencies” that limited the strength of the results. These included not describing the method of randomization or concealment of allocation. Furthermore, more than 20% of the sample was omitted from the analysis of the results without any explanation. Tthe same group of investigators did both of the RCTs, which were thus subject to the same flaws in methods. They are described in detail further in this review.
The MSAC recommended that “public funding for sacral nerve stimulator implantation should not be supported at this time” based on a lack of long-term efficacy data and the high rate of adverse events.
Sacral nerve stimulation for the treatment of refractory urge incontinence
The RCT by Schmidt et al. (32) formed the basis of the evidence for the Blue Cross and Blue Shield Association’s assessment.(8) The RCT compared SNS to no treatment in patients with refractory urge incontinence. Whereas the authors of the MSAC assessment noted that this RCT neglected to indicate what happened to the 20% of the patients omitted from the analysis, the Blue Cross and Blue Shield Association assessment reported that the patients were omitted because there was insufficient follow-up data. It is unclear where the Blue Cross obtained this information because it is not reported in the study.
To assess the effectiveness, safety, and costing of SNS for refractory urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence.
To address effectiveness, the following outcomes were examined:
To evaluate safety, these outcomes were examined:
Quality of life was assessed as follows:
Studies were included in this report if they met of the following criteria:
Studies were excluded from this report if any of the following applied:
The Medical Advisory Secretariat also conducted Internet searches of Medscape and the manufacturer’s Web site (2) to identify product information and recent reports on trials that were unpublished but were presented at international conferences. In addition, the Web site Current Controlled Trials (3) was searched for ongoing RCTs investigating the role of SNS in the management of voiding conditions.
The detailed literature search strategy is in Appendix 1.
Four RCTs were identified that met the inclusion criteria for this review. (30-32;45) Two compared SNS to no treatment in patients with urge incontinence, 1 compared SNS to no treatment in patients with urgency-frequency, and 1 compared SNS to no treatment in patients with urinary retention. In addition to the 4 RCTs, the Medical Advisory Secretariat identified 9 prospective case series, 4 retrospective studies, and 4 abstracts.
In 1999, Schmidt et al. (32) reported the results of a prospective, multicentre, non-blinded RCT that investigated the effectiveness of SNS compared with no treatment in patients with urge incontinence who were refractory to standard treatments (including behaviour modification and medications). One hundred and fifty-five patients were eligible for the trial, and underwent sacral nerve test stimulation. Ninety-eight patients had success with the test stimulation, and thus were randomized to receive either SNS or no treatment. Schmidt et al. did not note if they compared the treatment and control groups at baseline to ensure equivalency between groups on age, sex, previous treatments for incontinence, and duration of incontinence symptoms. After 6 months, the patients in the control group were offered the SNS procedure. Schmidt et al. (32) only reported 6-month follow-up data for 76 patients. They did not discuss what happened to the remaining 22 patients. Originally, 4 of these had been randomized to the control group, and 18 had been randomized to the treatment group.
Schmidt et al. also did not report an intent-to-treat analysis. That is, they conducted their analysis of the data based on 76 patients, rather than the whole randomized sample of 98 patients. This is problematic, because it is unclear from the study what happened to these patients, especially considering most of the missing patients were from the treatment group (n = 18). The patients could have been missing for a variety of reasons, including insufficient data at the time of analysis to include them in the 6-month follow-up; drop-out due to adverse effects or ineffectiveness; or living far away from the treatment centre. In their analysis of the 76 patients, Schmidt et al. reported that the number of daily incontinence episodes, the severity of the incontinence, and the number of pads used daily decreased for patients in the treatment group compared with those in the control group at 6 months (P < .0001).
The Medical Advisory Secretariat reanalyzed Schmidt et al.’s results and included all patients who were randomized (N = 98). Based on the data available in the study, the Medical Advisory Secretariat conservatively assumed that all 18 missing patients in the treatment group failed to respond to SNS, and the 4 missing patients in the control group showed no improvement at 6 months compared to baseline. Table 6 compares Schmidt et al.’s results with 76 patients to the Medical Advisory Secretariat’s intent-to-treat results. Even when all of the missing patients were included in the analysis as having failed treatment, the results still indicate a significant improvement in the patients receiving SNS compared to no treatment (P < .001). Even though there were limitations in the design and reporting of this RCT, it seems that SNS is effective in patients with urge incontinence compared to no treatment.
The RCT by Weil et al. (45) randomized 44 patients with refractory urge incontinence to receive either SNS (treatment) or to continue their prior conservation management (control). At 6 months, the patients in the control group also underwent SNS. At 6 months, Weil et al. reported that the mean number of incontinent episodes per day, mean leakage severity, and the mean pad usage was significantly lower in the treatment group than the control group (P < .05). It is not clear whether the study was powered to detect a significant difference in the outcomes between the treatment and the control group. Table 7 describes the characteristics of the 2 RCTs.
Hassouna et al. (30) investigated the role of SNS among patients with urgency-frequency. This study was done by the same group who did the RCT for urge incontinence (32) and the RCT for urinary retention (31).
Hassouna et al. did not indicate how many patients underwent the test stimulation procedure. Rather, they reported that 51 patients had successful test stimulation results and thus were randomized to receive either SNS or no treatment. A study by Siegel et al. (48) on the long-term results of this study noted that 220 patients with urgency-frequency underwent test stimulation. This suggests that only 23% of the patients had successful test stimulations and therefore were eligible for inclusion in Hassouna et al.’s RCT. Of note is that Hassouna et al. did not compare the treatment and control groups at baseline to ensure their demographic information was similar. Like the other RCTs, patients in the control group were offered SNS after 6 months.
Hassouna et al. compared the mean volume per void between the treatment and the control group at 6 months, and found that it significantly increased among patients in the treatment group compared with those in the control group (P < .0001). They also compared outcomes of patients in the treatment group at baseline to those of patients in the treatment group at 6 months, and found that there was a significant improvement in the amount voided at 6 months compared to baseline (P < .01). Based on the data in the study, the Medical Advisory Secretariat calculated unpaired t-tests for the treatment and control groups at 6 months for all outcomes, assuming a normal distribution of outcomes (Table 8). All of the outcomes were significant, with the exception of detrusor pressure at first sensation of fullness.
Hassouna et al. did not measure pelvic pain in association with urgency-frequency in their study; however, 3 studies (1 retrospective review (49), 2 case series (26;50)) were identified that examined the use of SNS in patients with chronic pelvic pain associated with urgency-frequency. Table 9 briefly outlines these studies.
A retrospective study of 21 women suffering from interstitial cystitis (a symptom complex of urinary urgency-frequency and pelvic pain) who underwent SNS reported that these women significantly decreased their intake of narcotics to manage pelvic pain. (49) Four patients stopped using narcotics after implantation, and the mean reduction in morphine dose was 36%. The authors of the study did not indicate how long the women were followed-up and if the reduction in morphine dose was maintained over time. The prospective case series by Comiter et al. (50) reported a significant decrease in pelvic pain in patients who underwent SNS at median follow-up (P < .01). The other prospective case series did not report statistical significance values; however, they did report that on a scale of 0 to 10 (10 being the most painful), patients scores fell from a mean of 9.7 before implantation to 4.4 at median follow-up. (26)
One RCT (31)was identified that compared the role of SNS to no treatment in patients with urinary retention. (Patients with retention due to obstruction were excluded.) Jonas et al. reported that 177 patients with urinary retention underwent test stimulation; however, only 68 (38%) were successful. Thirty-seven patients were randomly assigned to have SNS, and 31 were randomized to receive no treatment. The patients in the control group were offered SNS after 6 months. Even though 68 patients were randomized, results were only reported for 51 patients. Of the missing 17 patients, Jonas et al. wrote, “6 [patients] were not yet enrolled for 6 months, 3 had been lost to follow-up and 8 were in the study but did not turn in a voiding diary.” Jonas et al. did not account for these patients in their analysis, thus they did not report an intent-to-treat analysis. Of the missing patients, 8 were in the treatment group and 9 were in the control group. Jonas et al. did not report the reasons for missing patient data according to treatment group. Nor did they compare the treatment and control groups at baseline to ensure similarity across demographic characteristics.
In their analysis of the 51 patients, Jonas et al. reported that the number catheterizations per day significantly decreased in the treatment group compared with those in the control group at 6 months (P < .0001). The Medical Advisory Secretariat reanalyzed Jonas et al.’s results to include all patients who were randomized to the study originally (N = 68). Based on the data available, the Medical Advisory Secretariat conservatively assumed that the 8 missing patients in the treatment group failed to respond to SNS t, and the 9 missing patients in the control group showed no improvement in the number of daily catheterizations at 6 months compared to baseline. Table 10 shows the comparison. Even when all of the missing patients were included in the analysis as having failed treatment, there was still a significant improvement in the number of daily catheterizations at 6 months for the patients who had SNS (P ≤ .001).
Jonas et al. reported the results of the RCT by comparing the outcomes of the treatment group at baseline to the outcomes of the treatment group at 6 months, rather than reporting the outcomes in the control group compared to the outcomes in the treatment group. Based on the data provided in the study, the Medical Advisory Secretariat has calculated unpaired t-tests, assuming a normal distribution of outcomes. Table 11 details the results of this analysis. All 6 outcomes measured were significantly improved after 6 months in the treatment group compared to the control group (P < .0001).
In addition to the RCT by Jonas et al. (31), a retrospective study was identified that examined SNS in patients with urinary retention. Dasgupta et al. (51) reviewed the case records of 26 women with urinary retention who had undergone SNS between 1996 and 2002. Twenty-five (96%) of the 26 women regained voiding function immediately after surgery; however, after a mean follow-up of 37 months (range 2 to 73 months) 20 (77%) women were voiding spontaneously.
In July 2004, NICE published a thorough systematic review of the efficacy and safety of SNS in patients with fecal incontinence. (10) The review identified 6 prospective case series (1 unpublished, 2 non-English-language), 1 double-blind crossover trial (N = 2), and a prospective non-RCT that met the inclusion criteria. Since the release of the systematic review, 3 additional case series (52-54) were identified. No RCTs were identified that compared SNS to no treatment in patients with fecal incontinence. The case series are described in Table 12.
A multisite study (55) reported in the NICE systematic review was published in German in 2003. Since the publication of the systematic review, the multisite study has been published in English. (54) The multisite case series study by Jarrett et al. (53) reported that of the 46 patients who underwent SNS, all but 2 had improved continence functioning after a median follow-up of 12 months. Nineteen (41%) patients were fully continent at the median follow-up. In the 39 patients where there were measurements for the ability to defer defecation, all but 5 of them had improved in delaying defecation from a median of 1 minute at baseline to 10 minutes at median follow-up (P < .001). All 3 case series reported there was a significant decrease in weekly incontinence episodes at median follow-up in patients with fecal incontinence who had the SNS device.
There are still several unanswered questions about long-term follow-up. Medtronic Inc. reports that the battery should last 5 to 10 years depending on the use of the device, but no studies were identified that included patients to the point of battery failure. Six studies (including 3 abstracts) (48;51;56-59) were identified that reported long-term follow-up results for patients who had received SNS. The length of follow-up varied across the studies, ranging from 1.5 years to more than 5 years. The rate of explantation ranged from 11.5% to 20.5%. All of the studies reported that the implant was still effective in the majority of the patients at the time of follow-up. Table 13 provides an overview of these studies.
In the study by Dasgupta et al. (51) 26 women with urinary retention underwent SNS. Immediately after surgery, 25 women were voiding spontaneously. After a median follow-up of 37 months, 20 (77%) women were voiding spontaneously. Three women reported loss of efficacy and 2 had their stimulators deactivated because of pregnancy. Loss of efficacy was the most frequently reported complication. Dasgupta et al. reported 7 episodes of loss of efficacy. (They did not indicate the number of patients which experienced loss of efficacy.)
Siegel et al. (48) reported long-term follow-up of the patients included in the RCTs by Schmidt et al. (32), Hassouna et al. (30) and Jonas et al. (31) investigating the role of SNS in patients with urge incontinence, urgency-frequency, and urinary retention, respectively. This case series was included in previous health technology assessment, but the Medical Advisory Secretariat chose to include it because it reported on the 3 RCTs described in this systematic review. They reported long-term follow-up for 112 patients included in the 3 studies. They defined long-term follow-up as 1.5 to 3 years after SNS. Their analysis included 23 (20%) patients who had the device explanted. Despite the explantations, Siegel et al. reported that the patients had maintained significant improvements in bladder function in the 3 years since implantation. This was the case for the 3 subgroups of patients: those with urge incontinence; urgency-frequency; and urinary retention. The surgical revision rate was 33%. The most frequent revisions were relocation of the stimulator due to pain and readjustment of the lead after migration. Despite these revisions, 84% of the patients who had the implant said they were satisfied with it and would recommend it to a friend or family member.
Janknegt et al. (59) also reported long-term follow-up data from the patients in Schmidt et al.’s RCT (32). There is overlap between this study and the results reported by Siegel et al.; (48) however, it is not possible to tell how many patients were included in both analyses. They reported long-term (at least 12 months) follow-up results for 96 patients who had had SNS for refractory urge incontinence. Similar to the case series by Siegel et al., this study was reviewed in other health technology assessments; however, it was included in the review because it provided follow-up of the patients in one of the RCTs reported in this assessment. Eleven (11%) explants were reported among the 96 patients: 9 patients had explants because the device didn’t work, 1 had an explant due to chronic leg pain, and 1 had an explant due to a bowel dysfunction. After a mean of 30.8 months (range, 12 to 60 months), 25 patients reported no daily incontinence episodes, and 35 reported daily incontinence episodes were lower by at least 50%, resulting in an overall success rate of 62%. At baseline, 90 patients reported using diapers or pads to manage leaks. At the mean follow-up, 30 patients said they no longer used pads, and 25 patients reported a reduction in diaper usage by at least 50%.
Additionally, Janknegt et al. attempted to establish factors that would predict success with SNS. They compared sex, age, psychological history, previous surgical procedures, duration of urinary symptoms, number of test stimulation procedures, lead location, medication use at 12 months and neurostimulator polarity (unipolar versus bipolar) in patients for whom SNS was successful, and in those for whom it was not. The significant difference in success with SNS was sex-based. They reported that 10 (91%) of the 11 men in the study had success with SNS compared to 50 (59%) of the 85 women in the study (P = .048). This result should be interpreted cautiously because the ratio of men to women was unbalanced. In all of the studies, there were more women than there were men.
In a 2004 abstract for the International Continence Society Conference, van Voskuilen et al. (56) reported follow-up results for 157 patients (82% women) who had SNS implants for urinary urge incontinence (70%) or urinary retention (30%). The mean age at implantation was 47.5 years. At a mean follow-up of 64 months (range 13–154 months), 61% of the patients had “good results.” This was defined as “complete and lasting disappearance of symptoms or satisfactory symptom relief.” Among the 157 patients, 118 (75%)reported at least 1 adverse event. Thirty-four patients had surgical revision to manage the adverse events. Thirty-one patients had their devices explanted. The length of time until the explantation was not reported in the abstract.
To evaluate safety, complications, and quality of life associated with having SNS, studies for urge incontinence, urgency-frequency, urinary retention, and fecal incontinence, were combined. Table 14 shows the complications and adverse effects encountered by patients in the studies included in this review.
Siegel et al. (48) reported long-term follow-up results on the patients included in the RCTs by Schmidt et al. (32), Hassouna et al., (30) and Jonas et al. (31) on SNS in patients with urge incontinence, urgency-frequency and urinary retention, respectively. There was a 33% surgical revision rate among the 219 patients in the 3 studies. Nonetheless, 84% of the patients said they would repeat the procedure and would recommend it to a friend or family member.
Das et al.’s prospective case series (60) measured depression and health-related quality of life in patients who had SNS. The sample for this study comprised patients in the same RCTs noted above. Das et al. did not explain why they reported on depression and quality of life for only 89 patients, when there were 219 patients in the 3 studies. They found that 73% of the patients had some degree of depression at baseline. At 3 months, 41% of the patients in the treatment group had some degree of depression compared with 73% of patients in the control group (P < .05). These degrees of depression were consistent at 6 months and 12 months for both groups.
However, when the depression scores were analyzed according to bladder dysfunction, only patients with urge incontinence who had SNS showed a significant improvement in depression scores at 3 months compared to the control group. There was no significant difference in depression among urge incontinence patients only at 6 months. Patients with urgency-frequency and urinary retention who received SNS did not report significantly improved depression scores compared with patients with the same diagnoses who did not receive SNS at 3 or 6 months. This could be because the study was not powered to detect differences among subgroups of patients.
Dasgupta et al. (51) did a retrospective study of 26 women who had had SNS for urinary retention. They found that 54% of the women required surgical revision after surgery, mostly due to loss of effectiveness (27%), pain at the implant site (23%), and leg pain (23%). No explants were reported; however, the authors did not indicate if the surgical revisions improved effectiveness or relieved pain.
Jarrett et al. (53) did a multisite case series of 46 patients who had SNS for fecal incontinence. They compared scores on quality of life at the last follow-up to scores at baseline and found that general health was significantly better (P = .024), as was mental health (P = .008), social function (P = .013), and vitality (P = .009).
t is interesting to note that Jarrett and colleagues compared the quality of life scores for the patients in the study to the mean scores of residents in the United Kingdom. Even though the scores improved from baseline to last follow-up, they were still lower than the national mean scores in the United Kingdom. For instance, the score for general health at baseline was 49 (out of 100), and it increased to 55 at last follow-up; however, the mean score in the United Kingdom was 72 for general health. They did not provide a statistical comparison between the mean scores of the United Kingdom and the patients in their study. Matzel et al. (54) also reported improvements in quality of life from baseline to 12 months after implantation in patients with fecal incontinence; however, the scores were still lower than in the general population of the United Kingdom. The only 2 variables where the patients improved enough to match the United Kingdom’s general population score were social functioning (P = .0002) and mental health (P = .0007). The scores after implantation for physical functioning, vitality, bodily pain, and general health were substantially lower than the mean scores of the general population (no statistical analysis provided).
Jarrett et al. (53) reported no major complications among the 46 patients implanted with the device to manage fecal incontinence. Four patients had lead displacements. Three patients had their leads repositioned, and 1 patient wanted the device explanted. Three patients reported pain at the implant site shortly after the device was implanted in the abdomen. All 3 of these patients received a local anesthetic and steroids to manage the pain. Patients who subsequently received implants had them placed in their buttocks.
In the multicentre study by Matzel et al., (54) 8 severe adverse events were reported among the 37 patients. (The authors of the study did not indicate if a patient experienced more than 1 adverse event.) Pain was the most frequently reported adverse event. One patient had the device explanted due to a deterioration of bowel symptoms. The resolution rate among the severe adverse events was 100%.
Uludag et al. (52) in a case series that voiding function immediately improved after implantation in all 50 patients; however, after 1 year, 2 (4%) patients had decreased efficacy of the device, and subsequently had the devices explanted. Two others had their devices explanted due to infection at the site of implantation. Four patients required revision surgery due to technical problems with the device.
Thus, there is a relatively high rate of surgical revision (approximately 33%) reported in the studies examining the safety of SNS, however, no permanent injuries or deaths were reported in any of the studies identified. As a comparison, the permanent implantation of an artificial urinary sphincter is a surgical procedure that has been shown to treat incontinence (including urge, stress, and mixed) effectively; however, the surgical revision rate associated with it is about 50%. (24)
The Medical Advisory Secretariat did a cost analysis of SNS for the management of urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence. Previous health technology assessments and the peer-reviewed literature from 2000 to January 2005 were searched using the keywords listed in the methods for the literature review.
The health technology assessment by the MSAC in Australia (44) contained an “indicative analysis” of the cost of treatment and the reduction in personal costs (e.g., incontinence supplies). In addition to MSAC’s analysis, the Medical Advisory Secretariat found an abstract by Cappellano et al. (61) that was presented at the International Continence Society conference in 2003, which described the economical and social impact of SNS.
The MSAC found that it was more economical for patients to continue paying for incontinence supplies rather than to receive SNS. They noted that the savings in costs for specialized appliances and laundry is between $277.70 (AU) and $574.20 (AU) per patient with urge incontinence over 6 months, and about $245 (AU) per patient with urinary retention over 6 months. The cost-effectiveness ratio for SNS treatment for urge incontinence was estimated at about $35,000 (AU) (about $32,000 Canadian) per additional patient free of incontinence at 6 months follow-up. (44) Importantly, the MSAC did not account for quality of life in its analysis.
The abstract by Cappellano et al. (61) compared 3-month health services utilization before implantation with 3-month health services utilization between 9 and 12 months after implantation in patients with urinary conditions. They found that visits to a general practitioner fell from 1.1 to 0.5 on average per patient (P < .01), while visits to the urologist were relatively unchanged (from 1.5 to 1.2). The number of diagnostic tests decreased, on average, from 2 to 0.8 per person (P < .01). There was also a reduction in the daily use of incontinence pads from 2.1 (3 months per patient expenses of 120.96 Euros) to 0.5 (3 months per patient expenses of 28.8 Euros) (P = .08). For urinary retention, the use of catheters decreased from 1.1 at baseline (3 months per patient expenses of 178.2 Euros) to 0.1 (3 months per patient expenses of 16.2 Euros). Cappellano et al. concluded that SNS improves the economic management of patients with lower urinary tract dysfunction by reducing the number of pads and catheters required and the number of physician visits. They acknowledged that the decrease in physician visits did not occur until about 1 year after implantation, mostly owing to refinements of the stimulation (e.g., altering voltage settings). They also cited studies that indicated that SNS improves quality of life.
One possible reason for the difference between the economic reports could be due to the different time periods covered by each: MSAC determined costs over 6 months; Cappellano and colleagues, 12 months.
Disclaimer: This economic analysis represents an estimate only, based on assumptions and costing methodologies that have been explicitly stated. These estimates will change if different assumptions and costing methodologies are applied for the purpose of developing implementation plans for the technology.
In fiscal year (FY) 2003, 7 hospital separations were identified from the discharge abstracts database that could have been associated with SNS (A combination of ICD-10 CA diagnosis codes and CCI procedure codes were used. See Appendix 2 for a list.) No cases were identified in FY 2002. To determine the cost per case, the prospectively adjusted for complexity resource intensity weights (PAC-10 weights) were used based on a weight of 1.0 having a dollar value of $4,505 during FY 2003 (Personal Communication, May 2005). The median PAC-10 weight in FY 2003 was 0.63, which was used as a measure of central tendency of the distribution over the mean owing to heavy skewing to the right. The associated cost was $2,823 per hospital separation. The total cost based on the most current volume of 7 hospital separations was $19,763 (CDN).
The cost of a single-lead stimulation device is approximately $10,000, and a dual-lead device is approximately $14,000. As a result, the current annual device costs based on current volumes would be in the range of $70,000 - $98,000. The implantable device generally lasts 5 −10 years, at which point it must be replaced.
Treatment involves an exploratory trial surgery (phase 1) which leads to permanent insertion of the device (phase 2) in 33% to 50% of the patients. There are 3 postoperative visits with either an urologist or a gastroenterologist.
The following fees have been adjusted upward by 2% to reflect the new OMA agreement.
Psychological assessment phase: (1 visit)
Note: 4 base units + 1 unit for each 15 minutes in first hour + 2 units per 15 minutes thereafter Assumption: Up to 2-hour surgery for phase 1
Note: 8 base units + 1 unit for each 15 minutes in first hour + 2 units per 15 minutes thereafter
Note: At most, 50% of patients who undergo preliminary trial qualify for full implant
Note: 33% of patients require revision of surgery due to pain at implant site, lead migration, or infection
Note: 13% of patients require an explant of device
Follow-up assessment/psychological visits and preliminary visit (3 postoperatively during the first year):
The following code is used for follow-up:
Note: Similar cost for follow-up for fecal incontinence
The estimated Ontario prevalence of people who might be eligible for the procedure with urge incontinence, urgency-frequency, urinary retention is between 1,268 - 6,283) (Table 15) and/or fecal incontinence is 274 - 2,895 (Table 16). It is important to note that the prevalence estimate for Ontario may be high because it is difficult to accurately predict the prevalence of urinary conditions (many people are embarrassed to talk about the condition), and it is also very difficult to estimate the number of people with urinary conditions whose symptoms are severe enough to consider undergoing surgery.
The following is a list of prescription medicines. Although SNS does not eliminate the need for prescription medications for the underlying symptoms, some patients will combine SNS with drug therapy if drug therapy has been somewhat effective. Table 17 shows the drugs prescribed in Ontario to manage urge incontinence. One recent abstract suggests that drug-related expenditures will be reduced by over 75%. (61)
According to the MSAC, (44) the cost saving in specialized appliances and laundry per patient is between $277.70 (AU) and $574.20 (AU) over 6 months for urge incontinence and about $245 (AU) for urinary retention over 6 months. The cost-effectiveness ratio for SNS treatment for urge incontinence is estimated at about $35,000 (AU) (about $32,000 Canadian) per additional patient free of incontinence at 6 months follow-up. (44)
Total costs in the Ontario-Based Economic Analysis determined that total costs were approximately $2,823 for Hospitalization Costs + $10,000 to $14,000 for Device Costs + $1,439 for OHIP physician costs.
In 2004, NICE released an Interventional Procedure Guidance relating to the evidence in the health technology assessment that stated that NICE supports the use SNS for urge incontinence and urgency-frequency provided that “the normal arrangements are in place for consent, audit and clinical governance.” (46) NICE released a similar statement on the use of SNS in patients with fecal incontinence. (66) No other guidelines were identified.
To qualify for SNS, a person must meet the following criteria:
Physicians will need to learn how to use the InterStim System for Urinary Control. Requirements for training include these:
The physician in Ontario who is currently performing SNS has funding from his hospital to perform 12 implant procedures per year. As noted in this review, the battery in the device lasts 5 to 10 years depending on its use. The physician started implanting these devices in patients in the late 1990s, and now the batteries are beginning to fail. The physician is facing an ethical dilemma in deciding which patients will receive the 12 implants that he has funding to implant per year—new implants or replacement implants? The physician indicated that the waiting list works on a first come, first served basis, with some exceptions made for people whose well-being is severely compromised (e.g., people with chronic urinary tract infections that will not heal due to repeated irritation due to catheterization).
Currently, patients who fail behaviour or drug therapy and patients who do not seek treatment because they are unaware of treatments or are too embarrassed to seek treatment manage incontinence with diapers or pads. Currently, there is no funding or subsidy provided in Ontario to people who manage their incontinence with diapers. Diapers cost about $1 CDN each. Absorbent pads are slightly less expensive. According to Schmidt et al., (32) patients with urge incontinence used a mean of 6.2 (SD, 5.0) pads or diapers per day before they underwent SNS. Based on these data, the cost of diapers per year for 1 patient with urge incontinence is about $2,263.
Urge incontinence, urgency-frequency, urinary retention, and fecal incontinence are not readily discussed conditions in the general population. Having one of these conditions affects a person’s ability to work, socialize, and interact with his or her community. SNS has the potential to treat a small proportion of these people. Nonetheless, there will still be many people suffering from urge incontinence, urgency-frequency, urinary retention, and fecal incontinence.
SNS is done internationally (United States, Canada, Australia, Europe, Japan, Latin America). In Canada, it is done in 4 provinces: Ontario, Quebec, Nova Scotia, and Alberta.
Currently, one physician in Ontario does SNS. The physician has funding from one hospital to implant 12 devices a year. As of January 2005, there is a waiting list of 47 people. No physicians in Ontario do SNS for patients who have only fecal incontinence.
SNS has been proven effective and safe in patients with refractory urge incontinence, urgency-frequency, urinary retention, and fecal incontinence. Studies have reported significant improvements in quality of life and reduced depression.
Nurse continence advisors are distributed throughout the province and treat people with voiding conditions with conservative treatments. These advisors may be the first health care professionals that patients with these conditions see; thus, their knowledge about treatments is crucial.
Family physicians need to be aware of all treatment options for patients with urge incontinence, urgency-frequency, urinary retention, and fecal incontinence, and where to refer patients to.
Specialists need to be aware of treatments for urge incontinence, urgency-frequency, urinary retention, and fecal incontinence. Training will need to be offered to specialists if they want to learn how to perform the SNS procedure.
There is level 2 evidence to support the effectiveness and safety of SNS for patients with urge incontinence, urgency-frequency, or urinary retention. There is level 4 evidence to support the effectiveness and safety of SNS for patients with fecal incontinence. The long-term follow-up data is still emerging; however, it appears that SNS is effective up to at least 5 years. Despite a somewhat high complication profile, no permanent injuries or deaths have been attributed to SNS. Most patients who receive the implant report that they would undergo the procedure again or recommend it to a friend, regardless of the complications.
Currently, only about one-quarter of people with urge incontinence, urgency-frequency, urinary retention, or fecal incontinence seek treatment. Drug and behaviour therapy effectively treat about 75% of the patients with these conditions who seek treatment. SNS has the potential to treat about 5% of these patients. This leaves 20% of patients who seek treatment with few alternatives (surgery or diapers). There is also the three-quarters of the people with one of these conditions that do not seek help for their symptoms because they are embarrassed or unaware of treatments.
SNS undoubtedly plays a role in the treatment of a small proportion of people with urge incontinence, urgency-frequency, urinary retention or fecal incontinence; however, a broader overview of the management of these voiding conditions may be beneficial in being able to treat as many people as possible with these conditions.
Sacral Nerve Stimulation Literature Search Strategy
Search date: November 6, 2004
Databases searched: Ovid MEDLINE, MELINE In-Process and Other Non-indexed Citations, Cochrane DSR and CCTR, INAHTA
Database: Ovid MEDLINE(R) <1966 to October Week 4 2004>
Database: EMBASE <1996 to 2004 Week 44>
Database: Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations <November 05, 2004>
Urge incontinence R32 or N39.4 (other specified urinary incontinence)
Urinary retention R33
Pelvic pain R10.2
Fecal incontinence R15
1.BX.09.HA-DV for phase 2 of implantation
This report should be cited as follows:
Medical Advisory Secretariat. Sacral nerve stimulation for urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence: an evidence-based analysis. Ontario Health Technology Assessment Series 2005; 5(3)
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The Medical Advisory Secretariat is part of the Ontario Ministry of Health and Long-Term Care. The mandate of the Medical Advisory Secretariat is to provide evidence-based policy advice on the coordinated uptake of health services and new health technologies in Ontario to the Ministry of Health and Long-Term Care and to the healthcare system. The aim is to ensure that residents of Ontario have access to the best available new health technologies that will improve patient outcomes.
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This evidence-based analysis was prepared by the Medical Advisory Secretariat, Ontario Ministry of Health and Long-Term Care, for the Ontario Health Technology Advisory Committee and developed from analysis, interpretation and comparison of scientific research and/or technology assessments conducted by other organizations. It also incorporates, when available, Ontario data, and information provided by experts and applicants to the Medical Advisory Secretariat to inform the analysis. While every effort has been made to do so, this document may not fully reflect all scientific research available. Additionally, other relevant scientific findings may have been reported since completion of the review. This evidence-based analysis is current to the date of publication. This analysis may be superceded by an updated publication on the same topic. Please check the Medical Advisory Secretariat Website for a list of all evidence-based analyses: http://www.health.gov.on.ca/ohtas