Bladder drugs and risk of dementia: Danish nationwide active comparator study.

Objective: To assess the association between cumulative use of anticholinergic bladder drugs and risk of all cause dementia compared with non-use and use of the β3 agonist bladder drug, mirabegron. Design: Danish nationwide active comparator study. Setting: National Danish registries, 1 January 2000 to 31 December 2022. Participants: 1 29 254 individuals with dementia were matched by age and sex to 646 270 controls without dementia, identified from a cohort of 2.26 million individuals aged 60-75 years between 2000 and 2022 with no previous dementia. Two separate nested case-control populations were studied: the general population and an active comparator population of 58 242 new users of bladder drugs (2198 developed dementia and were matched to 10 990 controls). Information on medication use was based on filled prescriptions and defined daily doses. Main outcome measures: Conditional logistic regression provided incidence rate ratios for associations between anticholinergic bladder drugs and dementia compared with non-use and mirabegron use adjusted for educational level, cardiovascular disease, diabetes, hypertension, dyslipidaemia, and Charlson Comorbidity Index. Results: Compared with non-use, ever use of anticholinergic bladder drugs was associated with an increased risk of dementia, with an incidence rate ratio of 1.44 (95% confidence interval (CI) 1.40 to 1.48). The incidence rate ratio increased with increasing cumulative drug use, from 1.31 (95% CI 1.27 to 1.36) for 1-90 defined daily doses to 1.68 (1.59 to 1.76) for >365 defined daily doses. Compared with non-use, all types of anticholinergic bladder drugs were associated with increased incidence rate ratios for dementia: tolterodine 1.43 (95% CI 1.38 to 1.49), solifenacin 1.37 (1.29 to 1.46), trospium 1.52 (1.37 to 1.67), and fesoterodine 1.48 (1.26 to 1.74). The increased risk of dementia with use of anticholinergic bladder drugs was not seen when compared directly with the use of the β3 agonist mirabegron (incidence rate ratio 0.82, 95% CI 0.74 to 0.92), irrespective of the type of anticholinergic drug. Conclusions: In this study, all types of anticholinergic bladder drugs were associated with an increased risk of dementia compared with non-use, but not when applying the active comparator of the β3 agonist bladder drug mirabegron. These findings highlight the relevance of using an active comparator. Future research should evaluate the risk of cognitive impairment and dementia for both types of bladder drugs.