National Health Service Research and Development Health Technology Assessment Program
Clegg et al.(5
) in 2002 identified 4 economic evaluations: 2 from the United States, 1 from the Netherlands, and 1 from Sweden. When these studies were assessed on standard criteria of internal and external validity, all were considered poor quality.
shows the results of the cost-effectiveness analysis by Clegg et al. All types of bariatric surgery were cost-effective when compared with nonsurgical management. AGB was cost-effective when VBG was considered as the standard treatment. AGB was not cost-effective when gastric bypass was considered as the standard treatment
Net Cost per Quality-Adjusted Life Year (QALY) Gained for Each Intervention
Clegg et al. noted there were several limitations of the cost-effectiveness analysis:
- Published studies often use different cut-off points to define obesity.
- There is a continuous relationship between BMI and the risk of a disease, such as diabetes, that is not considered when examining the risk of disease according to BMI ranges.
- Most studies looking at the impact of weight loss in obese people are short-term. However, long-term studies show these people have difficulty maintaining the weight loss. They should also distinguish intentional from unintentional weight loss. Unintentional weight loss may indicate disease-driven weight loss and is often associated with increased mortality and morbidity.
Neither the cost of plastic surgery nor the bariatric operating room equipment was included in Clegg’s economic analysis.
Gallagher et al. (37
) examined the cost of RYGB in the Veteran’s Administration health care system. They reviewed the records of 25 patients who had RYGB from 1999 to 2000. They calculated all obesity-related health care costs, including hospitalizations and outpatient visits, medications, and home health devices, at 12 months before and after the RYGB. All figures are in US currency.
The mean age of the patients was 52 years (SD, 2 years). The mean preoperative BMI was 52 kg/m2 (SD, 2 kg/m2). Mean follow-up was 18 months. The total cost of preoperative care was $10,778 (SD, $2,460) per patient ($5,476 [SD, $682] for outpatient visits; $12,221 [SD, $6,062] for hospital admissions; and $1,383 [SD, $349] for home health devices). The postoperative length of stay was 8 days (SD, 0.5days).
The cost of the gastric bypass was $8,976 (SD, $497) per patient ($1,900 per patient for the operating room and $7,076 [SD, $497] for intensive care unit and ward care).
For the first postoperative year, 6 patients had 12 admissions, but routine outpatient visits fell significantly from 55 (SD, 6) to 18 (SD, 2) postoperatively (P < .001). The cost of all care, excluding perioperative charges for 1 year after RYGB, was $2,840 (SD, $622) per patient (P = .005, compared with preoperative charges).
A limitation of the economic analyses by Gallagher et al. is that it did not include the costs of plastic surgery or the bariatric operating room equipment.
In the United States, Craig et al. (38
) estimated the cost-effectiveness (in 2001 United States currency) of gastric bypass versus no treatment from the payer perspective using a deterministic model (). The target group of patients were men and women aged 35 to 55 years with a BMI from 40 to 50 kg/m2
, who did not have cardiovascular disease and in whom conservative bariatric therapies had been unsuccessful. QALYs, life years, and cost were discounted during the patient’s lifetime.
Deterministic Decision Model Comparing Lifetime Expected Costs and Outcomes of Gastric Bypass and No Treatment of Severe Obesity From the Payer Perspective.
The base case cost-effectiveness ratios ranged from $5,000 to $16,000 (US) per QALY for women and from $10,000 to $35,600 (US) per QALY for men depending on age and initial BMI. These results suggest that gastric bypass is more cost-effective for women and those with a higher initial BMI (). However, because the reduction in lifetime medical costs was not greater than the cost of treatment in any risk subgroup, the analysis did not show that gastric bypass saved costs.
Analysis of 4 Risk Subgroups Representing the Upper and Lower Bounds of the Cost-Effectiveness Ratios.
Craig et al. noted that because estimates of treatment effectiveness were based on case series and subject to patient selection bias, the authors set the lower bound of percentage loss of excess weight to 38%, more than one-third less than the base case estimate. Therefore, the cost-effectiveness ratio for a 45-year-old man with a BMI of 40 kg/m2 was $57,200 (US) per QALY. For a woman of the same age and BMI, it was $28,000 (US) per QALY. Further analysis suggested that the 38% estimate increased the cost-effectiveness ratio beyond $50,000 (US) per QALY for a few subgroups of older, less obese men.
Craig et al. concluded that gastric bypass does not save costs from the payer’s perspective. However, the cost-effectiveness ratio estimates compare favourably with those of other accepted interventions and appear robust to parameter variation, especially among women and younger, more obese men. Compared with no treatment, gastric bypass is cost-effective.
Limitations of the study by Craig et al. are as follows:
- The sample consisted of patients who were severely obese but who did not have chronic medical conditions typically associated with obesity (i.e., diabetes, heart disease, and hypertension). Results may have been different if patients with comorbid conditions were included.
- Included were patients who had been repeatedly unsuccessful at conservative interventions, which the authors acknowledge is in agreement with clinical guidelines (diet, exercise, and behaviour therapy). Of note, the authors stated that failure of pharmacotherapy is not a requirement, although it is common practice to attempt all conservative treatments before undergoing invasive procedures.
- Several obesity-related costs were excluded because of insufficient evidence. Nonmedical costs were excluded. These included decreased productivity, lost wages, and other indirect costs associated with comorbid conditions.
Cooney et al. (39
) examined the impact of a standardized care regimen or clinical pathway on hospital length of stay, resource use, and postoperative complications after gastric bypass surgery.
The clinical pathway was developed by examining conventional management, reviewing the literature, and discussing proposed changes in care with a multidisciplinary team of health care providers. Each phase of care was evaluated to determine if it should be included in the pathway (standardized approach to patient care). The authors stated that the process of recovery from the gastric bypass procedure was described as various phases or steps of care (postoperative pain control, fluid and electrolyte balance, pulmonary function, gastrointestinal function, deep vein thrombosis, prophylaxis mobility, etc.). Patients were compared before the pathway (n = 16) and after the pathway (n = 12).
The mean hospital length of stay was 3 days shorter in the postpathway group (P < .001) ().
Impact of Gastric Bypass Pathway on Hospital Length of Stay.
Total hospital costs were lower in the postpathway group. Postpathway savings were greatest for room and board (34%), supplies (41%), and laboratory and radiology costs (50%) (). An increase in operating room costs (22%) was observed in the postpathway group (). This was due to an increase in anesthesia time (epidural catheter placement) and equipment costs (ultrasonic shears).
Impact of Gastric Bypass Clinical Pathway on Resource Use.
Operating Room Use by Gastric Bypass Patients.
Limitations of the study by Cooney et al. are as follows:
- There was a lack of long-term postoperative details (patient management after the patient leaves the hospital) for the postpathway plan (e.g., resolution of comorbid conditions).
- The sample size was small.
In a follow-up study, (40
) Cooney et al. reanalyzed hospital costs after identifying a 16% incidence of “cost outliers” after implementation of a clinical pathway. Medical records and costs for 91 gastric bypass patients were reviewed. Patients with costs more than 1 SD above the total mean hospital cost comprised the cost outlier group (n = 15). The other patients formed the normal cost group (n = 76).
Patient demographics were similar in both groups. Diabetes and severe medical comorbid conditions, especially sleep apnea and degenerative joint disease, were more common in the cost outlier group (60% versus 9.2%, P < .05). The incidence of major complications (33% versus 8%) was significantly higher in the cost outlier group (P < .05).
The authors concluded that despite utilization of a clinical pathway for gastric bypass surgery, 16% of patients were cost outliers. Factors associated with increased hospital costs after gastric bypass included severe comorbid conditions and the occurrence of major postoperative complications.
The updated study by Cooney et al. had all of the limitations of the original study. (39
Huerta et al. (41
) also examined the effect of a bariatric surgery (RYGB) clinical pathway on hospital cost and patient length of stay after its implementation in an academic health centre. The medical records of 182 consecutive patients that had RYGB were retrospectively reviewed before implementation of the pathway (Group 1). Data on length of stay, intensive care unit length of stay, standard variable cost, readmission rate, and rate of return to the operating room were collected. This information was compared with the data collected prospectively from 182 patients after implementing the pathway (Group 2).
The authors stated that the clinical pathway was developed by a committee of nurses, attending surgeons, internists, intensive care physicians, nutritionists, quality assurance specialists, and administrators to develop a uniformly agreed-upon approach to managing bariatric surgery patients.
Hospital cost per admission was 40% lower in Group 2 (P < .02). The mean length of stay fell from 4.05 days in Group 1 to 3.17 days in Group 2 (P < .033). The overall readmission rate fell from 4.2% in Group 1 to 3.2 % in Group 2 (P < .05). There were no between-group differences in morbidities. The authors concluded that implementation of a clinical pathway for bariatric surgery reduces costs and improves quality of care in an academic institution.
Postoperative management was bimonthly meetings with internists, nutritionists, surgeons, psychiatrists, and nurses. Patients were encouraged to exercise regularly, and there was an online support group.
The study by Huerta et al. did not provide long-term postoperative details (e.g., resolution of diabetes).
Using data from the SOS study, Narbro et al. (42
) did a cross-sectional comparison of the use of prescribed pharmaceuticals in 1286 obese people in the SOS intervention study and 958 randomly selected reference patients. The SOS study consists of 2 parts: a cross-sectional registry study and a controlled prospective intervention study that began in 1987. In addition, a cross-sectional population study of randomly selected people (1752 men and women aged 37 to 60) from the general population during 1994 to 1999 was examined. Medication changes for 6 years after bariatric surgery were evaluated in 510 surgically and 455 conventionally treated SOS study patients. The inclusion criteria for the SOS intervention study were age 37 to 60 years and a BMI of at least 34 kg/m2
for men and at least 38 kg/m2
for women. The SOS reference study is a population study.
The authors did a cross-sectional investigation comparing baseline data on the use and cost of medications from the first 1,294 consecutive patients (surgically and conventionally treated patients combined) in the SOS intervention study with corresponding data from baseline examinations in the reference study. Data on medications were available for 958 (54.7%) patients in the reference population and 1286 (99.4%) patients in the SOS intervention study.
To estimate the effect of surgical treatment and weight reduction on the use and cost of medications for 6 years, a longitudinal comparison was undertaken on the first 647 surgically treated patients and the first 647 conventionally treated patients from the SOS intervention study. These 1294 patients included between 1987 and 1992 were compared with the reference study (1994–1997). Six-year follow-up data were unavailable for 137 (21.2%) patients in the surgical group and 192 (29.7%) patients in the conventionally treated group.
Information on prescribed medications, including dosage, was collected from questionnaires filled out by all participants at inclusion in the SOS reference and intervention studies. The same questionnaires were used at the 6-month and 1, 2, 3, 4, and 6-year follow-up visits in the SOS intervention study. Temporary medications were excluded, and 1 person in the intervention study was excluded from the calculations because of extreme costs for cancer medications. The daily costs were calculated for each drug using the 1997 official price list of the National Corporation of Swedish Pharmacies.
Participants were asked about drug use during the previous 3 months. Assuming use of medications was the same for the whole period covered by the questionnaire, the daily costs were summed for each drug and individual to estimate the drug-specific medication cost for each period. To estimate the mean yearly cost during the 6-year follow-up after obesity treatment, a weighted mean of the period costs was calculated. All costs were reported in Swedish kronor (SEK).
Compared with the reference group, obese patients were significantly more often taking diabetes, cardiovascular disease, nonsteroidal anti-inflammatory and pain, and asthma medications (risk ratios ranging from 2.3–9.2). The mean annual costs for all medications were 1,387 (SEK; US $140) in obese patients and 783 (SEK; US $80) in the reference population (P < .001). The mean yearly medication costs during follow-up were 1849 (SEK; US $185) in surgically treated patients (weight change -16%) and 1,905 (SEK; US $190) in weight-stable conventionally treated patients (P = .87). The surgical group had lower costs for diabetes mellitus (difference -94 SEK/year [-US $9]) and cardiovascular disease medications (difference: 186 SEK/year [-US $19]) but higher costs for gastrointestinal tract disorder (difference: +135 SEK/year [US $13]), and anemia and vitamin deficiency medications (difference: +50 SEK/year [US $ 5]).
The authors concluded that the use and cost of medications are higher in obese versus reference populations. Surgical treatment for obesity lowers the cost of medications for diabetes mellitus and cardiovascular disease, but it increases other medication costs, thereby resulting in similar total costs for surgically and conventionally treated obese individuals for 6 years.
Limitations of the study by Narbro et al. are as follows:
- Baseline data for the intervention study population and the medication data for the general reference population were collected during different periods. Therefore, the introduction and use of new drugs may have affected the results.
- Data on medication use were available for approximately 55% of the reference population, and the health status of the nonrespondents was unknown.
- The SOS intervention study was based on self-selected patients who were recruited by advertisements in public media.
- Information on the use of medications was self-reported and was collected from questionnaires. This may have affected the reliability of the data.
- The study was not restricted to patients with morbid obesity: Inclusion criteria did not use the commonly accepted cut-off of a BMI of 40 or of 35 and comorbid conditions.
Nguyen et al. (43
) compared the costs of laparoscopic RYGB (n = 79) with open RYGB (n = 76) in a single-centre RCT conducted in the United States. The patient outcomes of this study have been included in the literature searches of previous health technology assessments.
Direct operative costs were higher for laparoscopic versus open RYGB ($4,992 [SD, $1927] vs. $3,591 [SD, $1000], P < .01). Laparoscopic RYGB required more Endo GIA (stapler) reloads than did open RYGB (13.4 [SD, 5.7] vs. 5.6 [SD, 2.7], P < .01). Hospital service costs were lower in the laparoscopic RYGB group ($2,519 [SD, $1712] vs. $3,742 [SD, $3978], P = .02). Nursing costs were lower for laparoscopic RYGB ($1,201 [SD, $821] vs. $1,975 [SD, $2773], P = .03). There were no significant differences in direct, indirect, or total costs between groups.
Nguyen et al. did not provide any data on the amount of postoperative pain, functional and social disability, or lost productivity.
Monk et al. (44
) retrospectively studied the first 100 patients who had undergone RYGB at a community teaching hospital in the United States. Sixty-four patients had adequate follow-up data available. The mean BMI was 57 kg/m2
(range 36.6–85.4 kg/m2
). The mean monthly medication expenditure fell from $317 (US) (SEM, $47.25; range $23.12–$1,801.19) preoperatively to $135 (SEM, $35.35; range $0.00–$1,122.72) postoperatively (P
A limitation of the study by Monk et al. is that is was a retrospective single-centre case series.
Potteiger et al., (45
) using retrospective data from the electronic database of 51 consecutive patients who had RYGB, reviewed prescription records preoperatively and at 3 and 9 months postoperatively.
The prevalence of diabetes and hypertension was 55.7% (29/53) and 44.3% (24/53), respectively; 34% (18/53) of patients had both. Preoperatively, patients were taking a mean 2.44 (SD, 1.86) medications that cost $187.24 (SD, $237.41) per month. Postoperatively, the mean number of medications fell to 0.56 (SD, 0.81; P < .001) at a monthly cost of $42.53 (SD, $116.60; P < .001).
Limitations of the study by Potteiger et al. include these:
- It was a retrospective case series
- There were no long-term data.
Sampalis et al. (46
) did an observational 2-cohort study comparing patients who had bariatric surgery between 1986 to 2002 to a control group of age- and gender-matched obese patients who had not undergone weight reduction surgery from the Quebec health insurance database. This study used data analyzed by Christou et al. (29
) already reviewed in this report. The cohorts were followed-up for up to 5 years. The primary outcome measure was overall direct health care costs. Secondary outcomes included cost analysis by diagnostic category for the treatment of new medical conditions after cohort inception.
Sampalis et al. found significant reductions in the mean EWL (67.1%, P < .001) and in the percent change in BMI (34.6%, P < .001) in the bariatric surgery cohort. Similar data were not reported for the control group.
The mean total cost per 1,000 patients for the 5 years following cohort inception are shown . After 5 years, the total cost per 1,000 patients for hospitalizations in the control cohort was 29% higher than for the bariatric patients (absolute difference = $5.7 million in 1996 Canadian currency in favour of weight reduction surgery).
Table 54: Mean Total Cost per 1,000 Patients for the 5 Years After Cohort Inception. From: Sampalis et al. (46)
Sampalis et al. (46
) said after 3.5 years, the initial investment for the weight-reduction surgery and related hospital care was compensated by a reduction in total costs, which corresponded to an expected amortization period of 3.5 years of the initial investment for bariatric surgery.
Limitations of the study by Sampalis et al. (46
) are as follows:
- All of the limitations of Christou et al. (29)
- The design of the study was retrospective.
Agren et al. (47
) looked at hospitalization length and costs for 962 surgically and conventionally treated obese patients from the SOS intervention study who were followed-up for 6 years.
After 6 years, weight change was -16.7% in the surgical group and +0.9% in the control group (P < .0001). The cumulative hospital stay over 6 years was 23.4 days in the surgical group and 6.9 days in the control group (P < .0001). The mean hospital cost for the surgical intervention was $4,300 (US). Incremental costs that could be attributable to obesity surgery averaged $1,200 (US) per year. After excluding hospitalizations for the surgical intervention and conditions common after bariatric surgery, there were no significant group differences in number of hospital days or hospitalization costs.
Agren and colleagues concluded that the mean weight reductions of 16% did not lower the hospitalization costs over 6 years. The lag time between improved cardiovascular risk factors induced by weight loss and an assumed lower incidence of cardiovascular disease that could decrease inpatient care is unknown.
Limitations of the study by Agren et al. are as follows:
- All of the limitations of the SOS study.
- It is possible that hospitalization costs would be reduced in a 10- to 20-year perspective.
In the United States, DeMaria et al. (48
) compared the outcomes of patients who had hand-assisted laparoscopic gastric bypass (n = 25) with those who had the open procedure (n = 62). Some surgeons use hand-assisted procedures to treat obesity because it is easier to do than the total laparoscopic procedure.
Preoperatively, hand-assisted gastric surgery patients did not differ significantly from open gastric bypass patients on age, sex, BMI, weight, or comorbid conditions. Length of hospital stay did not differ significantly between the groups (hand-assisted: 3.6 days (SD, 1.3); open: 4.2 days (SD, 4.6). However, total hospital costs were higher for the hand-assisted procedure: $14,725 (SD, $3089; US) versus $10,281 (SD, $3687; US; P < .01).
Follow-up showed that the risk of postoperative complications was similar for the hand-assisted and open surgery groups. This included marginal ulcer (16% versus 14.5%), stomal stenosis (24% versus 23%), and incisional hernia (20% versus 27%). There were no major wound infections or deaths in either group. One patient in each group developed a postoperative small bowel obstruction. Loss of excess weight in hand-assisted patients at 12 months postoperatively was 66% (SD, 14%). In the patients who had the open procedure, it was 77% (SD, 14%). The difference was not statistically significant.
A limitation of the study by De Maria et al. is that disability and time and return to work were not quantified.