Relationships Between Level and Change in Sarcopenia and Other Body Composition Components and Adverse Health Outcomes: Findings from the Health, Aging, and Body Composition Study

We investigated how baseline values and rates of decline in components of sarcopenia and other body composition parameters relate to adverse clinical outcomes using the Health, Aging, and Body Composition Study. 2689 participants aged 70–79 years were studied. Appendicular lean mass, whole body fat mass, and total hip BMD were ascertained using DXA; muscle strength by grip dynamometry; and muscle function by gait speed. Baseline values and 2–3 year conditional changes (independent of baseline) in each characteristic were examined as predictors of mortality, hospital admission, low trauma fracture, and recurrent falls in the subsequent 10–14 years using Cox regression (generalized estimating equations used for recurrent falls) with adjustment for sex, ethnicity, age, and potential confounders. Lower levels and greater declines in all parameters (excluding hip BMD level) were associated (p < 0.05) with increased rates of mortality; fully-adjusted hazard ratios per SD lower gait speed and grip strength were 1.27 (95% CI 1.19, 1.36) and 1.14 (1.07, 1.21), respectively. Risk factors of hospital admission included lower levels and greater declines in gait speed and grip strength, and greater declines in hip BMD. Lower levels and greater declines in fat mass and hip BMD were associated with low trauma fracture. Lower gait speed, higher fat mass, and both lower levels and greater declines in grip strength were related to recurrent falls. Lower baseline levels and greater declines in musculoskeletal parameters were related to adverse outcomes. Interventions to maximize peak levels in earlier life and reduce rates of age-related decline may reduce the burden of disease in this age group.

Two-Thirds of All Fractures Are Not Attributable to Osteoporosis and Advancing Age: Implications for Fracture Prevention

Context Although bone mineral density (BMD) is strongly associated with fracture and postfracture mortality, the burden of fractures attributable to low BMD has not been investigated. Objectives We sought to estimate the population attributable fraction of fractures and fracture-related mortality that can be attributed to low BMD. Design and Setting This study is a part of an ongoing population-based prospective cohort study, the Dubbo Osteoporosis Epidemiology study. In total, 3700 participants aged ≥50 years participated in the study. Low-trauma fracture was ascertained by X-ray reports, and mortality was ascertained from the Birth, Death and Marriage Registry. Results Overall, 21% of women and 11% of men had osteoporotic BMD. In univariable analysis, 21% and 16% of total fractures in women and men, respectively, were attributable to osteoporosis. Osteoporosis combined with advancing age (>70 years) accounted for 34% and 35% of fractures in women and men, respectively. However, these two factors accounted for ∼60% of hip fractures. About 99% and 66% of postfracture mortality in women and men, respectively, were attributable to advancing age, osteoporosis, and fracture; however, most of the attributable proportion was accounted for by advancing age. Conclusions A substantial health care burden of fracture is on people aged <70 years or nonosteoporosis, suggesting that treatment of people with osteoporosis is unlikely to reduce a large number of fractures in the general population.

Abstract TP160: Predicting Bone Fracture After Stroke—The Fracture Risk After Ischemic Stroke (FRAC-Stroke) Score

Background: Risk for low trauma fracture is increased by >30% after ischemic stroke. Additionally, in the IRIS trial pioglitazone therapy prevented ischemic stroke but increased fracture risk. We derived a risk score to predict risk of fracture one year after ischemic stroke. Methods: The Fracture Risk after Ischemic Stroke (FRAC-Stroke) Score was derived in 20,435 ischemic stroke patients from the Ontario Stroke Registry discharged from 2003-2012, using Fine-Gray competing risk regression. Candidate variables were medical conditions included in the validated World Health Organization FRAX risk score complemented by variables related to stroke severity. Registry patients were linked to population-based Ontario health administrative data to identify low trauma fractures (defined as any fracture of the femur, forearm, humerus, pelvis or vertebrae, excluding fractures resulting from trauma, motor vehicle accidents, falls from a height or in people with active cancer). The score was externally validated in 13,698 other ischemic stroke patients in the population-based Ontario stroke audit (2002-2012). Results: Mean age was 72; 42% were women. Low trauma fracture occurred within 1 year of discharge in 741/20435 (3.6%); cumulative incidence increased linearly throughout follow-up. Age, discharge modified Rankin score (mRS), and history of arthritis, osteoporosis, falls and previous fracture contributed significantly to the model. Model discrimination was good (c statistic 0.72). Including discharge mRS significantly improved discrimination (relative integrated discrimination index 8.7%). Fracture risk was highest in patients with mRS 3 and 4 but lowest in bedbound patients (mRS 5). From the lowest to the highest FRAC-Stroke quintile the cumulative incidence of 1-year low trauma fracture increased from 1% to 9%. Predicted and observed rates of fracture were similar in the external validation cohort. Conclusion: The FRAC-Stroke score allows the clinician to identify ischemic stroke patients at higher risk of low trauma fracture within one year. This information might be used to target patients for early bone densitometry screening to diagnose and manage osteoporosis, and to estimate baseline risk prior to starting pioglitazone therapy.