Psychometric Equivalence of the OAB-q in Danish, German, Polish, Swedish, and Turkish

Abstract

Objective Patient-reported outcomes (PROs) are measures of patients' health status provided directly by patients and when utilized in clinical trials, multiple language versions may be needed. The overactive bladder questionnaire (OAB-q), a self-administered PRO assessing symptom bother and health-related quality of life (HRQL) in patients with OAB, was developed in US English and has been translated into more than 40 languages. This analysis evaluated the psychometric equivalence of five language versions of the OAB-q. Methods The Disease Management Study (DMS) was a multicenter, double-blind, placebo-controlled, parallel group, randomized study in adults with OAB. Participants completed the OAB-q, 3-day micturition diaries, and the patient's perception of bladder condition (PPBC) at baseline and weeks 1 and 12 of treatment. Results Data from 398 patients from five countries were analyzed: Denmark (N = 71), Germany (N = 127), Poland (N = 60), Sweden (N = 94), and Turkey (N = 46). Participants were a mean of 57.4 years old; 31% were male; and almost all were Caucasian. Cronbach alphas for the OAB-q symptom bother subscale = 0.71 to 0.83 and 0.82 to 0.94 for the HRQL subscales (concern, coping, sleep, and social) across all five languages. OAB-q subscales were significantly correlated with PPBC in all languages. Mean baseline to week 12 change scores = −21.4 to −30.3 for symptom bother and 5.2 to 36.0 for the HRQL subscales. Effect sizes for the symptom bother subscale = 0.92 to 2.79 and 0.21 to 1.30 for the HRQL subscales. Conclusion OAB-q language versions of Danish, German, Polish, Swedish, and Turkish demonstrated acceptable psychometric characteristics, including internal consistency reliability, construct validity, and responsiveness.