Risks of Dementia After Treatment with an Anticholinergic, Beta-3 Agonist, or Combination of Both for an Overactive Bladder: A Korean National Cohort Study

Background and objective: An overactive bladder (OAB) is primarily managed with behavioural therapy and using anticholinergics and beta-3 agonists. Reports have shown that the use of anticholinergics by OAB patients was associated with an increased risk of new-onset dementia compared with those using beta-3 agonists. This study compares the risks of dementia among patients with an OAB starting on a beta-3 agonist alone, an anticholinergic alone, or a combination treatment.

Methods: Using data from the Korean National Health Insurance Service database, we studied a nationwide population cohort comprising patients newly diagnosed with an OAB who initiated their OAB medications between 2015 and 2020. The treatment types were categorised as anticholinergics (oxybutynin, solifenacin, tolterodine, trospium, fesoterodine, flavoxate, and propiverine) alone, a beta-3 agonist (mirabegron) alone, and combination therapy (an anticholinergic plus the beta-3 agonist). To evaluate the impact of cumulative drug exposure, we quantified the cumulative exposure to solifenacin and mirabegron as cumulative defined daily doses (cDDDs) using proportional hazards regression analyses, adjusted for factors known to be associated with dementia.

Key findings and limitations: Among the study's 3 452 705 patients, 671 974 were new users of a beta-3 agonist alone (19.5%), 1 943 414 new users of anticholinergics alone (56.3%), and 837 317 receiving combination therapy (24.3%). The most common anticholinergic used both alone and as part of a combination treatment was solifenacin (42.9% and 56.3%, respectively). There was an increased risk of dementia between the users of an anticholinergic alone (adjusted hazard ratio [aHR] = 1.213; 95% confidence interval [CI], 1.195-1.232) and those taking a combination treatment (aHR = 1.345; 95% CI, 1.323-1.366) compared with the users of beta-3 agonists alone after the adjustment of covariates. However, the incidence of dementia was also significantly higher, with an increase in the cumulative dose of mirabegron (aHR = 1.062 [1.021-1.106] for 28-120 cDDDs and aHR = 1.044 [1.004-1.084)] for patients who received >121 cDDDs compared with those who received <27 cDDDs). A marked increased risk of dementia was associated with the use of solifenacin, tolterodine, fesoterodine, and propiverine, both separately and in combination with mirabegron.

Conclusions and clinical implications: In this large Korean cohort, the use of anticholinergics with or without a beta-3 agonist increased the risk of new-onset dementia compared with the use of a beta-3 agonist alone. Given that the risk of dementia was most significantly elevated with combination treatments, care should be taken when considering combination treatment for OAB patients with risk factors for dementia. Furthermore, there could be a possible association between beta-3 agonists and dementia, although future studies are needed.

Patient summary: This study investigated the risk of dementia induced by overactive bladder (OAB) treatment in a large Korean cohort. Two representative OAB treatment drugs, anticholinergics and beta-3 agonists, both increased the risk of new-onset dementia. Clinicians should be cautious in using OAB treatment drugs since no drugs could be concluded as safe.