Recurrent fracture after an initial osteoporotic fracture is a major public health burden, with 15% to 25% of patients experiencing a second fracture within 10 years, according to recent analyses. And while non-vertebral fractures are common and costly to the healthcare system, may fractures are preventable with appropriate osteoporosis treatments. However, treatment rates among this patient population are low and decreasing over time, with recent studies suggesting only 13% to 21% of patients in the United States seek treatment after hip fracture.
Assessing Treatment Initiation
For a study published in JAMA, Rishi J. Desai, MS, PhD, and colleagues sought to determine the frequency and effectiveness of initiating osteoporosis medications for the prevention of subsequent fractures and estimate the risk reduction in subsequent nonvertebral fractures associated with treatment initiation in patients with hip fracture. “We wanted to study contemporary trends in use of these treatments and quantify the benefits in terms of fracture prevention,” adds Dr. Desai.
The researchers analyzed data on more than 97,000 patients aged 50 and older who had a hip fracture and were not receiving treatment with osteoporosis medications before their fracture. Rates of osteoporosis treatment initiation within 180 days of a hip fracture hospitalization were observed between January 1, 2004 and September 30, 2015.
As instrumental variable analyses are known to result in high variance in treatment effect estimation, Dr. Desai and colleagues evaluated multiple instrumental variables based on factors related to healthcare access, trends, and preferences, with the ultimate goal of selecting the most appropriate instrumental variables alone or in combination to optimize the bias-variance trade-offs:
- Calendar year: this variable is expected to be a strong determinant of treatment but is otherwise unlikely to be associated with fractures, since the patient population at risk for fractures may not vary much across time.
- Specialist access: a binary indicator of access vs no access to specialists based on patients’ medical visit with specialists who are most likely to prescribe osteoporosis treatments (rheumatologists or endocrinologists) in a period of 6 months prior to the study index date.
- Geographic variation in prescribing patterns: identified patients’ geographic location using metropolitan statistical area codes from enrollment files and excluded patients for whom metropolitan statistical area codes were not recorded.
- Hospital preference: previous studies have used the choice of a specific treatment option in the most recent patient seen by a particular prescriber to define preference-based instrumental variables. The study team modified this approach to create a more robust preference-based instrumental variable that can take into account the patient case mix.
Rates on the Decline
A continuous decline was observed in osteoporosis medication initiation rates, from 9.8% in 2004 to 3.3% in 2015 (Table). After adjusting for measured and unmeasured confounding with an instrumental variable approach, a difference of 4.2 events per 100 person-years was observed in the rate of subsequent fractures associated with treatment initiation.
“We have long known that osteoporosis screening rates and treatment rates are low in general, but our results are intriguing in part because they focus on a high-risk population of hip fracture patients, all of whom should be considered for osteoporosis treatment according to National Osteoporosis Foundation recommendations,” says Dr. Desai. “Even in these patients, we saw a monotonic decline in treatment initiation,” says Dr. Desai. “Such low use of evidence-based treatments, many of which are available at a low cost as generics, can lead to an increase in preventable fracture cases in frail, elderly individuals. A recent study found that age-adjusted hip fracture rates from 2013 to 2015 were higher than projected, resulting in an estimated increase of more than 11,000 hip fractures, many of which could be attributed to the dismal treatment rates we documented in our study.”
Additional analyses showed that low treatment rates were worse in men and not explained by disproportionate underuse in older or frail patients.
“Collaborative care models, such as fracture liaison services, which can coordinate post-fracture care in these patients who are likely under the care of multiple clinicians, may be important to reverse the trend we see,” says Dr. Desai. “Improved patient and primary care provider education is important to increase awareness regarding current evidence that suggests a low risk of serious adverse events and robust effectiveness of these treatments in preventing recurrent fractures.”
Dr. Desai adds that future research should address comparative effectiveness of various treatment options and determine the ideal length of treatments to optimize benefit-risk tradeoff.