Systematic reviews and analyses of administrative data were performed to determine the appropriate use of bone mineral density (BMD) assessments using dual energy x-ray absorptiometry (DXA), and the associated trends in wrist and hip fractures in Ontario.
Dual Energy X-ray Absorptiometry Bone Mineral Density Assessment
Dual energy x-ray absorptiometry bone densitometers measure bone density based on differential absorption of 2 x-ray beams by bone and soft tissues. It is the gold standard for detecting and diagnosing osteoporosis, a systemic disease characterized by low bone density and altered bone structure, resulting in low bone strength and increased risk of fractures. The test is fast (approximately 10 minutes) and accurate (exceeds 90% at the hip), with low radiation (1/3 to 1/5 of that from a chest x-ray). DXA densitometers are licensed as Class 3 medical devices in Canada. The World Health Organization has established criteria for osteoporosis and osteopenia based on DXA BMD measurements: osteoporosis is defined as a BMD that is >2.5 standard deviations below the mean BMD for normal young adults (i.e. T-score <–2.5), while osteopenia is defined as BMD that is more than 1 standard deviation but less than 2.5 standard deviation below the mean for normal young adults (i.e. T-score< –1 & ≥–2.5). DXA densitometry is presently an insured health service in Ontario.
Burden of Disease
The Canadian Multicenter Osteoporosis Study (CaMos) found that 16% of Canadian women and 6.6% of Canadian men have osteoporosis based on the WHO criteria, with prevalence increasing with age. Osteopenia was found in 49.6% of Canadian women and 39% of Canadian men. In Ontario, it is estimated that nearly 530,000 Ontarians have some degrees of osteoporosis. Osteoporosis-related fragility fractures occur most often in the wrist, femur and pelvis. These fractures, particularly those in the hip, are associated with increased mortality, and decreased functional capacity and quality of life. A Canadian study showed that at 1 year after a hip fracture, the mortality rate was 20%. Another 20% required institutional care, 40% were unable to walk independently, and there was lower health-related quality of life due to attributes such as pain, decreased mobility and decreased ability to self-care. The cost of osteoporosis and osteoporotic fractures in Canada was estimated to be $1.3 billion in 1993.
Guidelines for Bone Mineral Density Testing
With 2 exceptions, almost all guidelines address only women. None of the guidelines recommend blanket population-based BMD testing. Instead, all guidelines recommend BMD testing in people at risk of osteoporosis, predominantly women aged 65 years or older. For women under 65 years of age, BMD testing is recommended only if one major or two minor risk factors for osteoporosis exist. Osteoporosis Canada did not restrict its recommendations to women, and thus their guidelines apply to both sexes. Major risk factors are age greater than or equal to 65 years, a history of previous fractures, family history (especially parental history) of fracture, and medication or disease conditions that affect bone metabolism (such as long-term glucocorticoid therapy). Minor risk factors include low body mass index, low calcium intake, alcohol consumption, and smoking.
Current Funding for Bone Mineral Density Testing
The Ontario Health Insurance Program (OHIP) Schedule presently reimburses DXA BMD at the hip and spine. Measurements at both sites are required if feasible. Patients at low risk of accelerated bone loss are limited to one BMD test within any 24-month period, but there are no restrictions on people at high risk. The total fee including the professional and technical components for a test involving 2 or more sites is $106.00 (Cdn).
Method of Review
This review consisted of 2 parts. The first part was an analysis of Ontario administrative data relating to DXA BMD, wrist and hip fractures, and use of antiresorptive drugs in people aged 65 years and older. The Institute for Clinical Evaluative Sciences extracted data from the OHIP claims database, the Canadian Institute for Health Information hospital discharge abstract database, the National Ambulatory Care Reporting System, and the Ontario Drug Benefit database using OHIP and ICD-10 codes. The data was analyzed to examine the trends in DXA BMD use from 1992 to 2005, and to identify areas requiring improvement.
The second part included systematic reviews and analyses of evidence relating to issues identified in the analyses of utilization data. Altogether, 8 reviews and qualitative syntheses were performed, consisting of 28 published systematic reviews and/or meta-analyses, 34 randomized controlled trials, and 63 observational studies.
Findings of Utilization Analysis
Analysis of administrative data showed a 10-fold increase in the number of BMD tests in Ontario between 1993 and 2005.
OHIP claims for BMD tests are presently increasing at a rate of 6 to 7% per year. Approximately 500,000 tests were performed in 2005/06 with an age-adjusted rate of 8,600 tests per 100,000 population.
Women accounted for 90 % of all BMD tests performed in the province.
In 2005/06, there was a 2-fold variation in the rate of DXA BMD tests across local integrated health networks, but a 10-fold variation between the county with the highest rate (Toronto) and that with the lowest rate (Kenora). The analysis also showed that:
With the increased use of BMD, there was a concomitant increase in the use of antiresorptive drugs (as shown in people 65 years and older) and a decrease in the rate of hip fractures in people age 50 years and older.
Repeat BMD made up approximately 41% of all tests. Most of the people (>90%) who had annual BMD tests in a 2-year or 3-year period were coded as being at high risk for osteoporosis.
18% (20,865) of the people who had a repeat BMD within a 24-month period and 34% (98,058) of the people who had one BMD test in a 3-year period were under 65 years, had no fracture in the year, and coded as low-risk.
Only 19% of people age greater than 65 years underwent BMD testing and 41% received osteoporosis treatment during the year following a fracture.
Men accounted for 24% of all hip fractures and 21 % of all wrist fractures, but only 10% of BMD tests. The rates of BMD tests and treatment in men after a fracture were only half of those in women.
In both men and women, the rate of hip and wrist fractures mainly increased after age 65 with the sharpest increase occurring after age 80 years.
Findings of Systematic Review and Analysis
Serial Bone Mineral Density Testing for People Not Receiving Osteoporosis Treatment
A systematic review showed that the mean rate of bone loss in people not receiving osteoporosis treatment (including postmenopausal women) is generally less than 1% per year. Higher rates of bone loss were reported for people with disease conditions or on medications that affect bone metabolism. In order to be considered a genuine biological change, the change in BMD between serial measurements must exceed the least significant change (variability) of the testing, ranging from 2.77% to 8% for precisions ranging from 1% to 3% respectively. Progression in BMD was analyzed, using different rates of baseline BMD values, rates of bone loss, precision, and BMD value for initiating treatment. The analyses showed that serial BMD measurements every 24 months (as per OHIP policy for low-risk individuals) is not necessary for people with no major risk factors for osteoporosis, provided that the baseline BMD is normal (T-score ≥ –1), and the rate of bone loss is less than or equal to 1% per year. The analyses showed that for someone with a normal baseline BMD and a rate of bone loss of less than 1% per year, the change in BMD is not likely to exceed least significant change (even for a 1% precision) in less than 3 years after the baseline test, and is not likely to drop to a BMD level that requires initiation of treatment in less than 16 years after the baseline test.
Serial Bone Mineral Density Testing in People Receiving Osteoporosis Therapy
Seven published meta-analysis of randomized controlled trials (RCTs) and 2 recent RCTs on BMD monitoring during osteoporosis therapy showed that although higher increases in BMD were generally associated with reduced risk of fracture, the change in BMD only explained a small percentage of the fracture risk reduction.
Studies showed that some people with small or no increase in BMD during treatment experienced significant fracture risk reduction, indicating that other factors such as improved bone microarchitecture might have contributed to fracture risk reduction.
There is conflicting evidence relating to the role of BMD testing in improving patient compliance with osteoporosis therapy.
Even though BMD may not be a perfect surrogate for reduction in fracture risk when monitoring responses to osteoporosis therapy, experts advised that it is still the only reliable test available for this purpose.
A systematic review conducted by the Medical Advisory Secretariat showed that the magnitude of increases in BMD during osteoporosis drug therapy varied among medications. Although most of the studies yielded mean percentage increases in BMD from baseline that did not exceed the least significant change for a 2% precision after 1 year of treatment, there were some exceptions.
Bone Mineral Density Testing and Treatment After a Fragility Fracture
A review of 3 published pooled analyses of observational studies and 12 prospective population-based observational studies showed that the presence of any prevalent fracture increases the relative risk for future fractures by approximately 2-fold or more. A review of 10 systematic reviews of RCTs and 3 additional RCTs showed that therapy with antiresorptive drugs significantly reduced the risk of vertebral fractures by 40 to 50% in postmenopausal osteoporotic women and osteoporotic men, and 2 antiresorptive drugs also reduced the risk of nonvertebral fractures by 30 to 50%. Evidence from observational studies in Canada and other jurisdictions suggests that patients who had undergone BMD measurements, particularly if a diagnosis of osteoporosis is made, were more likely to be given pharmacologic bone-sparing therapy. Despite these findings, the rate of BMD investigation and osteoporosis treatment after a fracture remained low (<20%) in Ontario as well as in other jurisdictions.
Bone Mineral Density Testing in Men
There are presently no specific Canadian guidelines for BMD screening in men. A review of the literature suggests that risk factors for fracture and the rate of vertebral deformity are similar for men and women, but the mortality rate after a hip fracture is higher in men compared with women. Two bisphosphonates had been shown to reduce the risk of vertebral and hip fractures in men. However, BMD testing and osteoporosis treatment were proportionately low in Ontario men in general, and particularly after a fracture, even though men accounted for 25% of the hip and wrist fractures. The Ontario data also showed that the rates of wrist fracture and hip fracture in men rose sharply in the 75- to 80-year age group.
Ontario-Based Economic Analysis
The economic analysis focused on analyzing the economic impact of decreasing future hip fractures by increasing the rate of BMD testing in men and women age greater than or equal to 65 years following a hip or wrist fracture. A decision analysis showed the above strategy, especially when enhanced by improved reporting of BMD tests, to be cost-effective, resulting in a cost-effectiveness ratio ranging from $2,285 (Cdn) per fracture avoided (worst-case scenario) to $1,981 (Cdn) per fracture avoided (best-case scenario). A budget impact analysis estimated that shifting utilization of BMD testing from the low risk population to high risk populations within Ontario would result in a saving of $0.85 million to $1.5 million (Cdn) to the health system. The potential net saving was estimated at $1.2 million to $5 million (Cdn) when the downstream cost-avoidance due to prevention of future hip fractures was factored into the analysis.
Other Factors for Consideration
There is a lack of standardization for BMD testing in Ontario. Two different standards are presently being used and experts suggest that variability in results from different facilities may lead to unnecessary testing. There is also no requirement for standardized equipment, procedure or reporting format. The current reimbursement policy for BMD testing encourages serial testing in people at low risk of accelerated bone loss. This review showed that biannual testing is not necessary for all cases. The lack of a database to collect clinical data on BMD testing makes it difficult to evaluate the clinical profiles of patients tested and outcomes of the BMD tests. There are ministry initiatives in progress under the Osteoporosis Program to address the development of a mandatory standardized requisition form for BMD tests to facilitate data collection and clinical decision-making. Work is also underway for developing guidelines for BMD testing in men and in perimenopausal women.
Increased use of BMD in Ontario since 1996 appears to be associated with increased use of antiresorptive medication and a decrease in hip and wrist fractures.
Data suggest that as many as 20% (98,000) of the DXA BMD tests in Ontario in 2005/06 were performed in people aged less than 65 years, with no fracture in the current year, and coded as being at low risk for accelerated bone loss; this is not consistent with current guidelines. Even though some of these people might have been incorrectly coded as low-risk, the number of tests in people truly at low risk could still be substantial.
Approximately 4% (21,000) of the DXA BMD tests in 2005/06 were repeat BMDs in low-risk individuals within a 24-month period. Even though this is in compliance with current OHIP reimbursement policies, evidence showed that biannual serial BMD testing is not necessary in individuals without major risk factors for fractures, provided that the baseline BMD is normal (T-score < –1). In this population, BMD measurements may be repeated in 3 to 5 years after the baseline test to establish the rate of bone loss, and further serial BMD tests may not be necessary for another 7 to 10 years if the rate of bone loss is no more than 1% per year. Precision of the test needs to be considered when interpreting serial BMD results.
Although changes in BMD may not be the perfect surrogate for reduction in fracture risk as a measure of response to osteoporosis treatment, experts advised that it is presently the only reliable test for monitoring response to treatment and to help motivate patients to continue treatment. Patients should not discontinue treatment if there is no increase in BMD after the first year of treatment. Lack of response or bone loss during treatment should prompt the physician to examine whether the patient is taking the medication appropriately.
Men and women who have had a fragility fracture at the hip, spine, wrist or shoulder are at increased risk of having a future fracture, but this population is presently under investigated and under treated. Additional efforts have to be made to communicate to physicians (particularly orthopaedic surgeons and family physicians) and the public about the need for a BMD test after fracture, and for initiating treatment if low BMD is found.
Men had a disproportionately low rate of BMD tests and osteoporosis treatment, especially after a fracture. Evidence and fracture data showed that the risk of hip and wrist fractures in men rises sharply at age 70 years.
Some counties had BMD utilization rates that were only 10% of that of the county with the highest utilization. The reasons for low utilization need to be explored and addressed.
Initiatives such as aligning reimbursement policy with current guidelines, developing specific guidelines for BMD testing in men and perimenopausal women, improving BMD reports to assist in clinical decision making, developing a registry to track BMD tests, improving access to BMD tests in remote/rural counties, establishing mechanisms to alert family physicians of fractures, and educating physicians and the public, will improve the appropriate utilization of BMD tests, and further decrease the rate of fractures in Ontario. Some of these initiatives such as developing guidelines for perimenopausal women and men, and developing a standardized requisition form for BMD testing, are currently in progress under the Ontario Osteoporosis Strategy.