Risk of Retention after OnabotulinumtoxinA Injection for Overactive Bladder in a Diverse Urban Population with High BMI and Comorbidity Rates

Importance: OnabotulinumtoxinA (BTX-A) injection is a third-line therapy for overactive bladder (OAB). Patients undergoing treatment have a 6.5% chance of requiring clean intermittent catheterization (CIC) due to postoperative urinary retention (POUR). Objective: The aim of this study was to evaluate risk factors for retention after BTX-A injections for OAB to decrease treatment hesitancy and enhance shared decision-making. Study Design: This is a retrospective review of patients who underwent BTX-A injection for OAB at an urban university hospital between November 2015 and January 2021. Patients with neurogenic OAB, incomplete follow-up, or concomitant vaginal surgery were excluded. The primary outcome was POUR requiring CIC or postvoid residual volume (PVR) >200 mL at follow-up visit. Secondary outcomes included number of BTX-A injections, interval to reinjection, and whether patients reported symptom improvement. Results: Our sample (N = 185) was 84% female with high prevalence of obesity (50%) and diabetes (32%). Twenty-one (11.4%) met the criteria for POUR with 17 (9.2%) requiring CIC. The retention and nonretention groups were similar in age, sex, smoking history, body mass index (BMI), hemogloblin A1c, and birth history, but significantly differed in preoperative PVR. Logistic regression revealed that patients with preoperative PVR 100+ mL had nearly 4-fold higher odds of POUR compared with patients with PVR less than 50 mL (odds ratio, 3.77; 95% confidence interval, 1.08-16.19). Conclusions: Our findings reassure patients with high BMI, as well as their physicians, that retention after BTX-A injection is not associated with BMI. However, patients presenting with high baseline PVR (100 + mL) should be counseled regarding a potentially higher risk of retention after BTX-A injection.