OBJECTIVES: To confirm the factor structure and evaluate the reliability, validity, and responsiveness of the OAB-q in medically complex elderly with overactive bladder (OAB). METHODS: Post-hoc analyses were conducted using data from a 12-week clinical trial for urgency urinary incontinence (UUI; N=566). Structure of the OAB-q was evaluated using a confirmatory factor analysis. Cronbach’s coefficient alpha (CCA) was used to assess reliability. Convergent validity was examined using Pearson’s and Spearmen Product-Moment correlations. Known-groups validity was assessed by evaluating differences in OAB-q scores in patients categorized according to UUI severity (mild, moderate, severe) and Patient Perception of Bladder Condition (PPBC) severity (Some Moderate Problems, Severe to Many Severe Problems). Effect size was used to examine responsiveness of the OAB-q, and an anchor-based approach was used to estimate the clinically important difference. RESULTS: Participants were mainly female (82.2%) and white (85.9%) with a mean age of 75.0 (± 6.4) years. Bentler’s Comparative Fit Index was satisfactory (0.90), path coefficients were statistically significant (t-values >1.96), and all standardized path coefficients were >0.40, indicating that a second-order measurement model with 5 domains and one aggregated domain holds true in the medically complex elderly population. OAB-q domains demonstrated good internal consistency (CCAs >0.7). Convergent validity was supported by moderate correlations (0.4 – 0.7) between OAB-q domains and other related patient-reported outcomes. Significant differences in OAB-q domain scores between groups of different severity based on UUI and PPBC provided evidence of known-groups validity. Responsiveness was demonstrated by statistically significant and clinically relevant differences in mean scores for the OAB-q domains over time between Baseline and Week 12 with effect sizes of those differences of about 0.2. CONCLUSIONS: The OAB-q has reliability, sound concurrent and discriminative validity with other measures, responsiveness to treatment, and is fit for purpose in medically complex elderly patients with OAB.