The responsiveness of the OAB-q among OAB patient subgroups

Although the majority of patients with overactive bladder (OAB) are continent, most patient-reported outcome measures for OAB were designed for patients with urinary incontinence. The overactive bladder questionnaire (OAB-q) was developed to assess symptom bother and HRQL among both continent and incontinent OAB patients; however, the responsiveness of the OAB-q among continent patients has not been evaluated. The purpose of this analysis was to assess the responsiveness of the OAB-q among OAB patient subgroups with a focus on continent patients.

Post-hoc analyses were conducted from two 12-week trials of tolterodine for the treatment of OAB. Patients completed the OAB-q and daily bladder diaries (assessing frequency, urgency, and incontinence episodes) at baseline, 4 weeks, and 12 weeks. Three patient subgroups were identified on the basis of continence status at all three timepoints: (1) continent; (2) incontinent; and (3) incontinent at baseline and continent by Week 12 (ITC). General linear models were used to compare changes from baseline, and Spearman correlations assessed the association between OAB-q changes and bladder diary changes. Effect sizes were computed separately for each group.

A total of 262 continent, 552 incontinent, and 397 ITC patients were included in this analysis. Continent patients tended to be younger than incontinent patients, and patients were predominantly female, although continent patients had the highest percentage of male patients in both studies. Compared with continent patients, patients who were incontinent at baseline tended to have greater symptom bother and lower HRQL at baseline. All OAB-q change scores were consistently greatest for the ITC group (12.1-33.9), and greater for continent patients (10.8-28.6) than for incontinent patients (7.6-20.1). All three groups of patients experienced reductions in frequency and urgency episodes, and these changes were significantly correlated with changes in the OAB-q scales. Among all three groups, effect sizes were in the moderate-to-large range for all OAB-q subscales except Social Interaction.

The OAB-q is highly responsive to change between continent and incontinent patients with OAB, and is a valid tool for measuring treatment outcomes among continent OAB patients.