Cross-cultural adaptation and validation of the Portuguese version of the Living with Asthma Questionnaire.

OBJECTIVE To translate and culturally adapt the Living with Asthma Questionnaire (LWAQ) to the Portuguese language and to test its reliability and validity. METHODS The Portuguese version of this disease-specific health-related quality of life measure was obtained with forward/backward translations, consensus panels and a pre-test. The Portuguese LWAQ and Medical Outcomes Study - 36 item Short Form (SF-36) questionnaires, and a form for the characteristics of the patients were administered to 61 subjects with asthma. RESULTS Reliability of LWAQ scores was good with Cronbach's alpha coefficients ranging from 0.70 to 0.97 [with the exception of "preoccupation" (0.62) construct, and "sleep" (0.67) and "effects on others" (0.47) domains] and intraclass correlation coefficients between 0.86 and 0.99. Construct validity was supported by the confirmation of predefined hypotheses involving expected significant correlations between LWAQ total, constructs and domains, and SF-36 dimensions with similar content. CONCLUSION The Portuguese LWAQ exhibited suitable psychometric properties, in terms of internal consistency, reproducibility and construct validity.