Association between cumulative anticholinergic burden and falls and fractures in patients with overactive bladder: US-based retrospective cohort study

Abstract

ObjectiveTo estimate the association between cumulative anticholinergic burden and falls and fractures in patients with overactive bladder (OAB).DesignA retrospective claims-based study (2007–2015) of patients with OAB; outcomes from a subset were contrasted to a non-OAB comparison.SettingUnited States, commercially and Medicare-insured population.Participants154 432 adults with OAB and 86 966 adults without OAB, mean age of 56 years, and 67.9% women.Main outcome measuresCumulative anticholinergic burden, a unitless value representing exposure over time, was estimated over the 12 months pre-index (‘at baseline’) and every 6 months post index. Burden was categorised as no burden (0), low burden (1–89), medium burden (90–499) or high burden (500+). Unadjusted rates of falls or fractures were estimated, and the increased risk associated with anticholinergic burden (measured at the closest 6-month interval prior to a fall or fracture) was assessed using a Cox proportional hazards model and a marginal structural model.ResultsMedian (IQR) baseline anticholinergic burden was 30 (0.0–314.0) and higher among older (≥65 years, 183 [3.0–713.0]) versus younger (<65 years, 13 [0.0–200.0]) adults. The unadjusted rate of falls or fractures over the period was 5.0 per 100 patient-years, ranging from 3.1 (95% CI 3.0–3.2) for those with no burden, to 7.4 (95% CI 7.1–7.6) for those with high burden at baseline. The adjusted risk of falls and fractures was greater with higher anticholinergic burden in the previous 6 months, with an HR of 1.2 (95% CI 1.2 to 1.3) for low burden versus no burden, to 1.4 (95% CI 1.3 to 1.4) for high versus no burden. Estimates from marginal structural models adjusting for time-varying covariates were lower but remained significantly higher with a higher anticholinergic burden. Rates of falls and fractures were approximately 40% higher among those with OAB (vs those without).ConclusionHigher levels of anticholinergic burden are associated with higher rates of falls and fractures, highlighting the importance of considering anticholinergic burden when treating patients with OAB.