The risk of delirium and falls or fractures with the use of overactive bladder anticholinergic medications

Objective — To determine if overactive bladder anticholinergic (OAB) anticholinergics have an increased risk of delirium or falls/fractures relative to OAB beta-3 agonist medications.

Methods — This was a retrospective, cohort study using linked administrative data from the universal healthcare system of Ontario, Canada. Participants were all residents >66 years of age who newly initiated an OAB medication between January 2016 and March 2020. Coprimary outcomes were evidence of a hospital visit with delirium, or for a fall/fracture. We used matching weights to make the three exposure groups (beta-3 agonist, oxybutynin, or newer OAB anticholinergics) comparable across 82 baseline characteristics. We examined both the risk during the first 30 days (logistic regression) and the risk during continuous usage (proportional hazards).

Results — We identified 103 024 older adults who started OAB medications. With matching weights, all measured variables were similar. The 30-day incidence of delirium was 0.31%, and fall/fracture was 1.07%; there was no significantly increased risk of either delirium (oxybutynin users OR 1.28 [95% CI 0.84-1.96], newer OAB anticholinergic users OR 0.92 [95% CI 0.58-1.46]) or falls/fractures (oxybutynin users OR 1.19 [95% CI 0.95-1.49], newer OAB anticholinergic users OR 1.14 [95% CI 0.91-1.43]) compared to beta-3 agonist users. With continuous usage, there was an increased HR of delirium among users of newer anticholinergics (HR 1.13, 95% CI 1.02-1.26) and an increased HR for fall/fracture among oxybutynin users (HR 1.13, 95% CI 1.02-1.24).

Conclusions — Compared to beta-3 agonists, the continuous use of oxybutynin is associated with a significantly increased risk of fall/fracture, and newer OAB anticholinergics are associated with a significantly increased risk of delirium.