Translation, cultural adaptation, and validation of the quality of well being self-administered questionnaire in general population in Indonesia

The quality of well being self-administered (QWB-SA) questionnaire is one of the generic instruments which can be used to measure the utility score to assess the quality-adjusted life years (QALYs) as an outcome parameter in pharmacoeconomics study. This research aimed to study the translation, cultural adaptation, and validation of the QWB-SA questionnaire in Indonesian language. This research was conducted among the general population of 459 people in Yogyakarta city. The translation was done using the forward-backward method by independent linguists, and then reviewed by a team consisting of linguists, methodologists, and pharmacists. The psychometric evaluations included face validity, internal-construct validity, convergent validity, and known-group validity tests, while the reliability test was the test-retest of reliability with the Spearman's rank correlation and Pearson test. The translation results and cultural adaptations were modified from the aspect of idiomatic, semantic and conceptual equivalence of the items on the QWB-SA questionnaire. The internal-construct validity showed a very strong and moderate correlation among dimensions and the QWB utility index. The convergent validity showed moderate-to-weak correlation compared to the Euro-quality of life-5 dimension questionnaire. The reliability test showed the Cronbach alpha coefficient of 0.626, and the test-retest of reliability showed a strong and moderate correlation. The QWB-SA questionnaire is valid and reliable, and can be used as an alternative to measure utility as a QALY's parameter in the health-economic evaluation.