Predicting imminent risk for fracture in patients aged 50 or older with osteoporosis using US claims data

Osteoporosis poses a significant and increasing health burden for the aging population [1, 2]. Osteoporotic fractures are common and associated with significant morbidity, mortality, and healthcare resource use [1, 3, 4]. Nonetheless, osteoporosis remains widely undertreated, even in patients with recent fractures [5, 6].

Several factors contribute to long-term fracture risk in patients with osteoporosis, including advanced age, fracture history, recent falls, low bone mineral density (BMD), and certain comorbidities, such as rheumatoid arthritis and causes of secondary osteoporosis [7, 8]. Risk can be quantified using fracture risk assessment tools (e.g., FRAX® and QFracture®), which estimate the 10-year risk of fracture [7, 9]. However, risk may not be constant over a 10-year period and being able to quantify vertebral or nonvertebral fracture risk over a shorter time period could assist clinicians in identifying and targeting therapy in patients with osteoporosis.

Risk factors that increase imminent risk, i.e., risk for fracture within the next 12 to 24 months, have not been well characterized. Studies suggest that after a recent fracture, the risk for a subsequent fracture is highest within the next 12 to 24 months [10‐13]. Other risk factors that may not be captured in long-term fracture risk assessment tools include specific comorbidities and medications affecting blood pressure, cognitive function, and/or patient awareness that may contribute to the risk for falls, thus increasing the risk of fracture [14‐18].

Using a large US commercial and Medicare supplemental claims data set, we undertook a case-control study aimed at identifying risk factors associated with imminent fracture in patients with osteoporosis who have not had a recent fracture.

Using a large claims database, this study identified factors contributing to imminent risk for hip vertebral, or nonvertebral fracture in patients with osteoporosis without recent fracture. Factors consistently associated with imminent risk for fracture included previous falls, advancing age, and poorer health status. Additional fall risk factors, such as specific comorbidities associated with impaired cognitive and physical function, concomitant medications, and factors related to mobility/frailty, were predictive at specific fracture sites.

This study assessed patients with osteoporosis without a recent fracture to identify clinical factors, other than recent fracture, that may contribute to imminent risk for fracture [20]; recent fracture is a recognized strong predictor of imminent fracture risk [21, 22]. Not surprisingly, falls and risk factors associated with falls were predictive of fracture in our study. Previous studies assessing imminent fracture risk and factors affecting fall risk have shown that advancing age, falls, comorbidities, and certain medications increase the risk of fracture [23‐25]. Both the National Osteoporosis Foundation and the World Health Organization have identified a history of falls as a major risk for fracture [2, 26]. Indeed, it has been reported that more than 90 % of hip fractures occur following a fall [27]. In addition, the incidence of falls increases with advancing age because of age-related physical and mental changes [28]. A systematic review of observational studies on risk factors for falling in community-dwelling older people showed that certain health conditions and impairments contributed independently to the risk of falls [29]. Conditions such as stroke, dementia, depression, and Parkinson’s disease are more common in older adults and may increase fall risk due to impact on cognition and physical function [28‐31]. Also, the medications used to manage these conditions can increase fall risk through their effect on cognitive and physical functioning [25, 28, 32]. For example, psychoactive medications (e.g., antidepressants, sedatives, antipsychotics), anti-Parkinson drugs, and adverse treatment events associated with these medications, including unsteadiness, impaired alertness, and dizziness, increase fall risk [15, 25, 29]. Moreover, the risk of falling increases with the number of risk factors [28].

Overall, the risk factors identified by our study for imminent risk for fracture are consistent with prior studies assessing fracture risk over longer time horizons [14‐17, 33‐36]. However, many of these risk factors are not accounted for in the long-term fracture risk assessment models commonly used in clinical practice. Indeed, it has been suggested that the lack of fall risk assessment with FRAX® may underestimate fracture probability, particularly in individuals with a history of falls, and inclusion could improve existing fracture prediction algorithms [37, 38].

Since older people commonly have multiple risk factors, including several comorbidities, and use multiple medications, knowledge about factors that increase risk may help guide identification, and appropriate treatment, of patients at imminent risk for fracture. Identification and management of these patients are important because of the increased probability of fracture and the associated morbidity, mortality, and cost of fracture [1, 3‐5, 39, 40]. Indeed, fractures are associated with decline in functional status and health-related quality of life [39, 41], lead to the development of comorbidities [2, 42], and increase the risk of death by 25 % [3].

Management could include therapy to increase BMD and interventions to increase bone strength, in addition to interventions to reduce falls. Although fall prevention strategies and interventions to decrease and/or protect from falls could be beneficial in reducing fracture, these options have had limited success and clinical studies have not consistently shown reductions in the risk of falling [43, 44]. Other management options may be required to strengthen bone and thus reduce the likelihood of fracture if a fall occurs.

Strengths of this study include the large study population over a time period of 2004 to 2012, with patients from across the USA and various types of health plans. This study had several limitations, including the potential for underreporting of falls and fractures; only falls resulting in medical events, procedures, and treatment were coded and included, and this may not be a reliable measure of frequency. We could not positively identify fragility fractures from medical claims based on ICD-9-CM diagnosis codes; therefore, we required closed or pathologic fracture in a specific treatment setting and/or accompanied by physician evaluation and management code, and E-codes to rule out fracture due to trauma. As a result, imminent risk may be underestimated in this study. Parental fracture history and BMD data, which are known risk factors for fractures, were unavailable from administrative claims data, limiting the number of risk factors examined. In addition, all comorbidities may not be captured by claims coding or may be miscoded. Owing to the smaller sample of males included in this study, analysis by sex was not undertaken, and thus sex differences could not be assessed. Finally, this population of patients who were either commercially insured or who had Medicare supplemental health insurance may not be representative of other insured or uninsured patient groups.

In conclusion, in men and women with osteoporosis and no recent fracture, multiple factors were associated with imminent risk for fracture, including older age, falls, comorbidities affecting cognitive or physical function, and other potential fall risk factors. Identification of factors putting patients at imminent risk for fracture may help risk stratify those patients most at need of immediate and appropriate treatment to decrease fracture risk.