Association between walking and hip fracture in women aged 65 and older: 20-year follow-up from the study of osteoporotic fractures

Summary: Hip fractures in elderly women pose significant healthcare challenges. Promoting walking for exercise as a cost-effective intervention may help reduce the risk of fractures in this population. Purpose: This study aimed to examine the relationship between walking and hip fracture risk among women aged 65 years and older. Methods: A 20-year prospective study (1986–2006) included 9704 women from the Study of Osteoporotic Fractures (SOF) in the USA. Participants were followed biennially, and walking exposure was assessed by the number of city blocks walked for exercise, routine activity, and total blocks walked daily. Cox regression models with time-varying covariates assessed associations, with competing risks addressed using Fine and Gray models. Penalized splines were used to explore dose–response relationships. Results: In total, 1419 hip fractures were identified through the study period. The mean and median follow-up times for hip fractures or censoring were 15.0 and 15.8 years in the walking for exercise group, vs. 13.2 and 13.7 years in the not walking for exercise group. The hip fracture incidence rate was 10.0 cases per 1000 person-years (py) in the walking for exercise group compared to 10.9 per 1000 py in the not walking for exercise group. All-cause mortality was 37.1 per 1000 py in the walking for exercise group compared to 46.4 per 1000 py in the not walking for exercise group. Adjusted models showed that walking for exercise significantly reduced hip fracture risk (HR, 0.864; 95% CI, 0.762–0.980; P = 0.0230), with each additional block walked for exercise reducing risk (HR per block, 0.986; 95% CI, 0.978–0.995; P = 0.0022). Walking for routine activities showed no significant association. Spline analysis indicated walking 16 blocks (≈3200 steps) daily significantly lowered hip fracture risk. Conclusion: Walking for exercise is linked to a reduced risk of hip fractures in elderly women. Walking the equivalent of 16 blocks or more (> 3200 steps) per day might be an effective way to reduce the risk of hip fractures in this vulnerable population.