Association between hand-grip strength and site-specific risks of major osteoporotic fracture: Results from the Japanese Population-based Osteoporosis Cohort Study

Abstract

ObjectivesTo investigate the association between hand-grip strength and site-specific risks of major osteoporotic fracture. Study designProspective cohort study. Main OutcomeAssociations between low hand-grip strength and increased risk of fracture at the distal forearm, vertebrae, and hip. MeasuresWe enrolled 1342 postmenopausal women aged 50 years or more into baseline and follow-up surveys of the Japanese Population-based Osteoporosis Cohort Study in 1996, 1999, 2002, or 2006. Fracture events were ascertained by follow-up surveys until 2011 or 2012. The Cox proportional hazards model was used to estimate hazard ratios (HRs) of hand-grip strength on fracture event. ResultsDuring a median follow-up of 15.2 years, 162 women sustained at least one osteoporotic fracture and 135 of these women sustained at least one major osteoporotic fracture, the larger group including 65, 38, 35, and 8 women with fractures of the distal forearm, vertebrae, hip, and proximal humerus, respectively. In the crude models, the associations between low hand-grip strength and increased risk of fracture at the distal forearm, vertebrae, and hip were significant; the HRs (95% confidence interval) of the lowest tertile of hand-grip strength were 2.02 (1.10–3.71), 11.35 (4.07–31.63), and 4.72 (1.79–12.47), respectively. Age adjustment attenuated the significance of hip fracture risk, and adjusting for bone mineral density attenuated the significance of distal forearm fracture risk. After additional adjustment for body mass index, history of diabetes mellitus, and calcium intake, the HR for vertebral fracture risk was 4.55 (1.56–13.27). When limiting the follow-up period to 5 and 10 years, low hand-grip strength was associated with an increased risk of distal forearm fracture independently of the aforementioned covariates; the HRs were 4.22 (1.12–15.95) and 2.52 (1.03–6.17), respectively. ConclusionsLow hand-grip strength is specifically associated with the risk of distal forearm fractures within 10 years and clinical vertebral fractures within 15 years or more in Japanese postmenopausal women.