Bladder antimuscarinic medications (BAMs) are commonly used among the aged population to manage urinary incontinence (UI), which is a frequent health problem among nursing home (NH) residents. However, a number of BAMs produce anticholinergic effects in the central nervous system (CNS), and may thereby cause delirium and lead to antipsychotic medication (APM) use.
This study examined the associations of BAMs and delirium incidence, and the associations of BAMs and APM initiations in NHs in Iowa. The main data sources were Medicare data, Minimum Data Set (MDS), and the Online Survey Certification and Reporting (OSCAR) or Survey Provided Enhanced Reporting (CASPER) from 2011 to 2014. Propensity score (PS) matching was used to balance baseline covariates between groups. Proportional hazard models with stratification on matched sets were used to analyze time to the study outcomes with 90-day, 183-day, 365-day, and the entire follow up. The study found out that compared with those without BAM use, residents with new BAM use had a non-significant higher risk for delirium incidence during the entire follow up, with a hazard ratio (HR) of 1.12, and 95% confidence interval (95% CI) of 0.92-1.36. New BAM users also had a non-significant higher risk for APM initiation (HR: 1.07, 95% CI: 0.78-1.49). Compared to residents who had new use of other BAMs, those who had new use of bladder-selective BAMs (darienacin and solifenacin) or quaternary-amine BAM (trospium) had a lower risk (HR: 0.83, 95% CI: 0.49-1.38) for delirium incidence and APM initiation (HR: 0.85, 95% CI: 0.36-2.03). However, none of the differences was statistically significant. APM prescribing rate at the facility level was not random in Iowa geographically. There were spatial variations in the associations between BAM prescribing rate and APM prescribing rate across the state.