Translation, Cultural Adaptation, and Validation of Short-Form 6D on the General Population in Indonesia

This study aims to translate, culturally adapt, and validate the Short-Form 6D (SF-6D) instruments for measuring quality of life as outcome parameters in pharmacoeconomic studies.

The forward-backward methods were applied to translate the SF-6D questionnaire. A preliminary Indonesian version of SF-6D questionnaire was field tested in samples of 470 adult general population. Test-retest reliability was assessed by using Spearman rank correlation coefficient and internal consistency with Cronbach α. Face validity was assessed descriptively based on the response of the respondents to all items in SF-6D. The construct validity test included internal construct validity and convergent validity, which was assessed by examining the correlation between the questionnaire and Euro-Quality of life-5D based on the scale of each domain. The known group method was used to test discriminant validity. Mann-Whitney U test was employed for comparing the utility score on dichotomous variables and Kruskal-Wallis H test was used for polychromatic variables.

The SF-6D was a valid and reliable questionnaire, indicated by the reliability coefficient of 0.725 and the value of each item ranging from 0.698 to 0.750. Construct validity indicated a strong correlation between physical functioning, role limitation, social functioning, pain, and mental health with the SF-6D utility score. Convergent validity showed a weak and moderate correlation between dimensions on SF-6D and Euro-Quality of life-5D.

The SF-6D questionnaire has been translated into Indonesian version. The SF-6D questionnaire is valid and reliable. Known group validity shows that the SF-6D could differentiate utility scores by age group and history present illness.