Antimuscarinic use among older adults with dementia and overactive bladder: a Medicare beneficiaries study.

OBJECTIVES: This study examined the incidence and predictors of antimuscarinic medication use including non-selective antimuscarinics among older adults with dementia and overactive bladder (OAB).
METHODS: The study used a new-user cohort design involving older adults (≥65 years) with dementia and OAB based on 2013-2015 Medicare data. Antimuscarinics included non-selective (oxybutynin, tolterodine, trospium, fesoterodine) and selective (solifenacin, darifenacin) medications. Descriptive statistics and multivariable logistic regression models were used to determine the incidence and predictors of new antimuscarinic use including non-selective antimuscarinics, respectively.
RESULTS: Of the 3.38 million Medicare beneficiaries with dementia, over one million (1.05) had OAB (31.03%). Of those, 287,612 (27.39%) were reported as prevalent antimuscarinics users. After applying continuous eligibility criteria, 21,848 (10.34%) incident antimuscarinic users were identified (77.6% non-selective; 22.4% selective). Most frequently reported antimuscarinics were oxybutynin (56.3%) and solifenacin (21.4%). Multivariable analysis revealed that patients ≥75 years, of black race, and those with schizophrenia, epilepsy, delirium, and Elixhauser's score were less likely to initiate antimuscarinics. Women, those with abnormal involuntary movements, bipolar disorder, gastroesophageal reflux disease, insomnia, irritable bowel syndrome, muscle spasm/low back pain, neuropathic pain, benign prostatic hyperplasia, falls/fractures, myasthenia gravis, narrow-angle glaucoma, Parkinson's disease, syncope, urinary tract infection and vulvovaginitis were more likely to initiate antimuscarinics. Further, patients with muscle spasms/low back pain, benign prostatic hyperplasia and those taking higher level anticholinergics had lower odds of receiving non-selective antimuscarinics, whereas white patients, black patients and those with schizophrenia and delirium were more likely to receive them.
CONCLUSIONS: Nearly one-third of dementia patients had OAB and over one-fourth of them used antimuscarinics. Majority of the incident users were prescribed non-selective antimuscarinics with several demographic and clinical factors contributing to their use. Given the high prevalence of OAB among dementia patients, there is a need to optimize their antimuscarinic use, considering their vulnerability for anticholinergic adverse effects.