Validation of Treatment Benefit Scale for Assessing Subjective Outcomes in Treatment of Overactive Bladder

Abstract

The assessment of patient-reported treatment benefits is a new efficacy outcome measure in overactive bladder (OAB) clinical trials. We conducted a retrospective psychometric validation of the Treatment Benefit Scale (TBS), a single-item scale used to assess the patient-reported benefits of treatment of OAB. The data were collected in the context of 2 large Phase III, randomized, double-blind, placebo-controlled, clinical trials of an antimuscarinic treatment of patients with OAB. Psychometric validation was conducted by examining (a) scale variability, (b) construct validity, (c) divergent validity, (d) known-group validity, and (e) responsiveness of the TBS. The data from 1766 patients were evaluated. The TBS correlated significantly with the expected domains of the King's Health Questionnaire, International Consultation on Incontinence Questionnaire-Short Form, and other patient-reported assessments, providing evidence of construct validity. Divergent validity was supported by a lower correlation between the TBS and unrelated domains of the KHQ. Statistically significant differences in the TBS scores between patients who received active OAB treatment and those receiving placebo provided evidence of known-group validity. Scale responsiveness was demonstrated by effect sizes >0.8. The TBS demonstrated strong validity and responsiveness for the trial population data, both separately for each trial and pooled. This validation has demonstrated the psychometric properties of the TBS as a patient-reported clinical efficacy outcome measure and suggests that it could provide clinically relevant data for assessing the treatment response among patients in clinical trials of new therapies for OAB.