Cross-Cultural Adaptation and Psychometric Evaluation of the Brazilian Portuguese Version of the Nocturia Quality-of-Life Questionnaire.

Introduction and hypothesis: The objective was to cross-culturally adapt and check for the reliability, internal consistency, and validity of the Nocturia Quality of Life Questionnaire (N-QoL) in Brazilian Portuguese (N-QoL-Br).

Methods: The questionnaire was translated according to international guidelines, included forward-translation, back-translation, and consensus among an expert committee. Participants with nocturia completed the Pittsburgh Sleep Quality Index, International Consultation on Incontinence Questionnaire Overactive Bladder, and the General Quality of Life Assessment Questionnaire SF-36 (Medical Outcomes Study 36-Item Short-Form Health Survey), in addition to the N-QoL-Br. The Brazilian version was applied in men and women with nocturia twice within a range of 4 weeks. Psychometric properties such as content validity, construct validity, internal consistency, and test-retest reliability were tested.

Results: Content validity was considered adequate. Eighty-four men and women participated in the study. Good internal consistency in the domains and final score of the N-QoL-Br was observed, with Cronbach α greater than 0.9. The test-retest reliability was also high, with an intraclass correlation coefficient greater than 0.9 for the domain sleep/energy, bother/concern, and total score (0.98, 0.98, and 0.97 respectively).

Conclusions: The Portuguese version of the N-QoL-Br presents good internal consistency and reproducibility and it can be considered adequate and valid for evaluating the impact of nocturia on the quality of life of men and women in the Brazilian population.