2026 Eastern States Conference

Authors: Samarah Wallace, PharmD; Ronald Carico Jr, PharmD, MPH; Rachele Subik, PharmD

Background/Objective: The purpose of this study is to compare the incidence of all-cause hospitalizations in patients aged 65 and older who are newly initiated on oxybutynin versus mirabegron for the treatment of overactive bladder over their first 3-months of treatment. 

Methods: This is a retrospective study comparing the incidence of all-cause hospitalizations in patients aged 65 and older who are newly initiated on oxybutynin versus mirabegron for the treatment of overactive bladder or a related condition over their first 3-months of treatment. Secondary outcomes include emergency department visits within the first year not leading to hospitalizations and initiation of a medication with potential to have been started due to an adverse event caused by oxybutynin or mirabegron. Patients were pulled from Marshall Health Internal Medicine’s electronic health record, and demographics and outcomes were assessed using the t-test or Fisher’s exact.

Results: The study assessed 338 patients over 65-years-old. 73% of the participants were female with 82% in the mirabegron arm and 66% being in the oxybutynin arm. 97% of participants were white with even distribution between both arms. The primary outcome was observed in 1% of patients in the mirabegron group and 7% in the oxybutynin group. Patients with oxybutynin had a 6-fold increased risk of hospitalization within the first 3 months. The secondary outcome for all-cause emergency department visits not resulting in a hospitalization within the first year of treatment was found to be non-significant. However, statistical significance was seen when assessing initiation of treatment for suspected adverse drug reactions to mirabegron or oxybutynin.

Conclusion: When evaluating patients 65-years-old and older who are receiving treatment with oxybutynin or mirabegron for overactive bladder, mirabegron demonstrates superior outcomes. Mirabegron, compared head-to head with oxybutynin, demonstrated a reduced incidence of adverse outcomes resulting in visits to the emergency department, hospital admissions, and the initiation of a medication that may have been started due to an adverse event.