Cross-cultural adaptation of the Brazilian-Portuguese version of the chronic urticaria quality-of-life questionnaire - CU-Q2oL

Background: Chronic urticaria (CU) is a debilitating skin disorder that affects patients' health related quality of life and the only questionnaire prepared specifically to CU is the Chronic Urticaria Quality of Life Questionnaire (CU-Q(2)oL). Objective: The purpose of this study was to cross-culturally adapt and validate the CU-Q(2)oL Brazilian-Portuguese version. Methods: Forward and back translation by three bilingual translators followed by pre-test was used to adapt the questionnaire. The CU-Q(2)oL was self-administered along with the Dermatology Life Quality Index (DLQI) in 112 patients with CU. Disease activity was assessed using the Urticaria Activity Score. Factor analysis was used to identify scales of the Brazilian portuguese CU-Q(2)oL. Internal consistency, convergent validity and known-group validity was determined. Reproducibility was evaluated by interclass correlation coefficient (ICC). Multiple linear regression was used to determine the predicting factors of CU-Q(2)oL results. Results: Factor analysis revealed a three-dimensional structure: sleep/mental status/eating (I), pruritus/impact on life activities (II) and swelling/limits/look (III), which explained 52.49% of the total variance. All scales showed excellent internal consistency. External construct validity was supported by correlations between the CUQ(2)oL and DLQI. The tool was found to be able to differentiate between patients with high and low levels of urticaria activity. Test-retest reliability was good to excellent (ICC = 0.69-0.86). Disease severity and urticaria type were the only factors predicting results. Conclusions: The CU-Q(2)oL Brazilian portuguese version was easily filled out, well accepted by the patients, demonstrated an acceptable validity and reliability and might be used to evaluate treatment outcomes and in clinical research.