Associations of Polypharmacy, Diuretics and Antipsychotics with Injurious Falls: A Population-Based Cohort Study

OBJECTIVE: Population ageing increases multimorbidity, which in turn contributes to polypharmacy, elevating fall risk through drug interactions and adverse effects on cognition or balance. Although polypharmacy is recognised as a risk factor, specific fall-risk-increasing drugs (FRIDs) may pose greater hazards. This study aimed to examine the associations of polypharmacy, diuretic and antipsychotic use with injurious falls among older adults. METHODS: Data from 952 participants (590 men and 362 women) aged ≥ 65 years in the Geelong Osteoporosis Study were linked with the Victorian Emergency Minimum Dataset. The outcome variable was time to first fall-related emergency presentation or injurious falls, with polypharmacy, diuretics and antipsychotics as exposure variables. The associations were examined using competing risk regression, with results presented as adjusted subdistribution hazard ratios (aSHR) and 95% confidence intervals. The population attributable fraction (PAF) was calculated to assess the population-level burden of polypharmacy, diuretics and antipsychotics on injurious falls. PAF indicates the proportion of cases in a population attributable to a specific risk factor. RESULTS: The median time to the first injurious fall was 8.0 years (IQR: 4.0-12.2). The overall incidence rate of injurious falls was 19.3 per 1000 person-years (95% CI: 16.9-22.0). Polypharmacy (aSHR = 2.62, 95% CI: 1.23-5.59), diuretic use (aSHR = 2.98, 95% CI: 1.81-4.92) and antipsychotic use (aSHR = 2.23, 95% CI: 1.23-4.07) increased the risk of injurious falls, with PAF of 17.1%, 23.0% and 4.6%, respectively. CONCLUSIONS: Polypharmacy, diuretic and antipsychotic use were associated with an increased risk of injurious falls, with diuretics accounting for the greatest population-level burden. These findings highlight the potential importance of routine medication review in identifying medications that may contribute to injurious falls among older adults. However, given the observational nature of this study, interventional studies are needed to determine whether medication review and deprescribing strategies can effectively reduce injurious falls and improve safety outcomes.