Polypharmacy, chronic kidney disease, and incident fragility fracture: a prospective cohort study.

INTRODUCTION: Polypharmacy is associated with an increased risk of fracture in aging populations, but no study has accounted for the impact of kidney function on this association. This study aimed to examine the association between polypharmacy and incident fragility fracture based on chronic kidney disease (CKD) status. MATERIALS AND METHODS: Participants were 2023 patients (55% men; mean age, 69 years) of Sado General Hospital enrolled in the Project in Sado for Total Health (PROST) between June 2008 and December 2016. Among these, 65%, 28%, and 7% had non-CKD, non-dialysis-dependent CKD, and dialysis-dependent CKD, respectively. Multivariable Cox proportional hazards analysis was conducted with adjustments for potential confounders. RESULTS: Prevalences of polypharmacy (≥ 5 medications) and hyperpolypharmacy (≥ 10 medications) among participants were 43% and 9% for non-CKD, 62% and 23% for non-dialysis-dependent CKD, and 85% and 34% for dialysis-dependent CKD, respectively. During a median follow-up of 5.6 years, 256 fractures occurred. More medications were associated with a higher risk of fractures. Specifically, compared to participants without polypharmacy, adjusted hazard ratios were 1.32 (95% CI 0.96-1.79) and 1.99 (1.35-2.92) for those with polypharmacy and hyperpolypharmacy, respectively, after adjusting for osteoporosis risk factors, CKD status, and comorbidities. No effect modification by CKD status was observed (interaction P = 0.51). Population-attributable fractions of hyperpolypharmacy for fracture were 9.9% in the total cohort and 42.1% in dialysis-dependent CKD patients. CONCLUSION: Hyperpolypharmacy is associated with an increased risk of fragility fracture regardless of CKD status, and has a strong impact on incident fragility fractures in dialysis-dependent CKD patients.