Risk of dementia associated with anticholinergic drugs for overactive bladder in adults aged ≥55 years: nested case-control study

Objective To investigate whether different anticholinergic drug treatments for overactive bladder have differential risks for incident dementia, in a large representative population of older adults in England. Design Nested case-control study. Setting General practices in England providing data to the Clinical Practice Research Datalink (CPRD) GOLD database, with linked patient admission records from secondary care (Hospital Episode Statistics), 1 January 2006 and 16 February 2022 Participants 170 742 patients aged >= 55 years, with a first reported diagnosis of dementia during the study period, matched by age, sex, and general practice with 804 385 individuals without dementia (controls). Interventions Cumulative drug use (defined using total standardised daily dose) of different anticholinergic drugs used for the treatment of an overactive bladder, and a non-anticholinergic drug, mirabegron, in the period 3-16 years before a diagnosis of dementia (or equivalent date in matched controls). Main outcome measures Odds ratios for onset of dementia associated with the different anticholinergic drugs used for the treatment of an overactive bladder, adjusted for sociodemographic characteristics, clinical comorbidities, and use of other anticholinergic drug treatments. Results The study population comprised 62.6% women, and median age was 83 (interquartile range 77-87) years. 15 418 (9.0%) patients with dementia and 63 369 (7.9%) controls without dementia had used anticholinergic drugs for the treatment of an overactive bladder in the 3-16 years before diagnosis (or equivalent date for controls). The adjusted odds ratio for dementia associated with the use of any anticholinergic drug used to treat an overactive bladder was 1.18 (95% confidence interval (CI) 1.16 to 1.20), and was higher in men (1.22, 1.18 to 1.26) than women (1.16, 1.13 to 1.19). The risk of dementia was substantially increased with the use of oxybutynin hydrochloride (adjusted odds ratio 1.31, 95% CI 1.21 to 1.42 and 1.28, 1.15 to 1.43 for use of 366-1095 and >1095 total standardised daily doses, respectively), solifenacin succinate (1.18, 1.09 to 1.27 and 1.29, 1.19 to 1.39), and tolterodine tartrate (1.27, 1.19 to 1.37 and 1.25, 1.17 to 1.34). No significant increases in the risk of dementia associated with darifenacin, fesoterodine fumarate, flavoxate hydrochloride, propiverine hydrochloride, and trospium chloride were found. The association between mirabegron, a non-anticholinergic drug, and dementia was variable across the dose categories and might be caused by previous use of anticholinergic drugs for the treatment of an overactive bladder in these individuals. Conclusions Of the different anticholinergic drugs used to treat an overactive bladder, oxybutynin hydrochloride, solifenacin succinate, and tolterodine tartrate were found to be most strongly associated with the risk of dementia in older adults. This finding emphasises the need for clinicians to take into account the possible long term risks and consequences of the available treatment options for an overactive bladder in older adults, and to consider prescribing alternative treatments that might be associated with a lower risk of dementia.