Factors associated with subsequent fractures post-hospital discharge for hip fracture: A single institution, retrospective cohort study.

Hip fractures in older adults are associated with substantial morbidity, loss of independence, and increased mortality, particularly in an aging society such as Japan. Although the risk of subsequent fractures after hip fracture is well recognized, discharge-related risk factors have not been fully evaluated. We conducted a retrospective cohort study using electronic medical records from Higashi-Kawaguchi Hospital, including patients hospitalized for hip fractures between April 1, 2015, and March 31, 2020. Patients were followed from the date of discharge to the date of subsequent fracture or to the last date of a confirmed medical record by our hospital until March 31, 2022. The incidence of subsequent fractures was determined, and hazard ratios (HRs) were calculated using Cox proportional hazards analysis to identify discharge-related risk factors. Among the 620 patients included, 131 patients (21.1%) experienced subsequent fractures, with 60 (9.7%) occurring within 12 months after discharge. Patients with subsequent fractures were more likely to be female, significantly older, and showed differences in osteoporosis medication use and the use of fracture risk-associated drugs in unadjusted analyses. The Cox proportional hazards model identified age by decade (HR: 1.71; 95% CI 1.35-2.16) and lower body mass index (BMI) (HR: 0.92; 95% CI: 0.86-0.97) as significant risk factors for subsequent fractures. These findings highlight the importance of discharge-based risk assessment and targeted post-discharge interventions for older patients and those with low BMI, given the high incidence of subsequent fractures within 12 months after discharge.