Our findings imply that simple functional tests can predict both hip fracture risk and excess mortality in postmenopausal women. Since the tests characterize general functional capacity (one-legged stance, squatting down, and grip strength), these simple measures should have clinical utility in the assessment of women at risk of falls and fragility fracture.
Introduction: Functional impairment is associated with the risk of fall, which is the leading cause of hip fracture. We aimed to determine how clinical assessments of functional impairment predict long-term hip fracture and mortality.
Methods: A population-based prospective cohort involved 2815 Caucasian women with the average baseline age of 59.1 years. The mean follow-up time in 1994-2014 was 18.3 years. Three functional tests and their combinations assessed at baseline were treated as dichotomous risk factors: (1) inability to squat down and touch the floor (SQ), (2) inability to stand on one leg for 10 s (SOL), and (3) having grip strength (GS) within the lowest quartile (≤ 58 kPa, mean 45.6 kPa). Bone mineral density (BMD) at the proximal femur was measured by DXA. Fractures and deaths were verified from registries. Hazard ratios were determined by using Cox proportional models. Age, body mass index (BMI), and BMD were included as covariates for fracture risk estimates. Age, BMI, and smoking were used for mortality.
Results: Altogether, 650 (23.1%) women had 718 follow-up fractures, including 86 hip fractures. The mortality during the follow-up was 16.8% (n = 473). Half of the women (56.8%, n = 1600) had none of the impairments and were regarded as the referent group. Overall, women with any of the three impairments (43.2%, n = 1215) had higher risks of any fracture, hip fracture, and death, with hazard ratios (HR) of 1.3 ((95% CI) 1.0-1.5, p < 0.01), 2.4 (1.5-3.4, p < 0.001), and 1.5 (1.3-1.8, p < 0.001), respectively. The strongest single predictor for hip fracture was failing to achieve a one-leg stand for 10 s (prevalence 7.1%, n = 200), followed by inability to squat down (27.0%, n = 759) and weak grip strength (24.4%, n = 688), with their respective HRs of 4.3 (2.3-8.0, p < 0.001), 3.1 (2.0-5.0, p < 0.001), and 2.0 (1.2-3.4, p < 0.001). In addition, age, lower BMD, BMI, and smoking were significant covariates.
Conclusions: These findings suggest that functional tests provide long-term prediction of fracture and death in postmenopausal women. Whether reversal of these impairments is associated with a reduction in adverse outcomes is an area for future trials.
Keywords: Aging; Fracture risk; Functional capacity; Mortality; Muscle strength.