Assessment of validity and reliability of the Indonesian version of Short Form 12 (SF-12)

INTRODUCTION: Psychometric evaluation of the 12-item Short-Form Health Survey (SF-12), a well-used scale for measuring health-related quality of life (HrQoL), has not been done in general populations in Indonesia. This study assessed the validity and reliability of the SF-12 in middle-aged and older adults. METHODS: Participants self-completed the SF-12 and SF-36. Scaling assumptions, internal consistency reliability, and 1-week test-retest reliability were assessed for the SF-12. Confirmatory factor analysis was conducted to assess its construct validity. Correlations between SF-12 and SF-36 component scores were computed to assess convergent and divergent validity. Effect size differences were calculated between SF-12 and SF-36 component scores for assessing criterion validity. RESULTS: In total, 161 adults aged 46-81 years (70% female) participated in this study. Scaling assumptions were satisfactory. Internal consistency for the SF-12 Physical Component Summary (PCS-12) and the Mental Component Summary (MCS-12) were acceptable (a = 0.72 and 0.73, respectively) and test-retest reliability was excellent (ICC = 0.88 and 0.75, respectively). A moderate fit of the original two-latent structure to the data was found (root mean square error of approximation [RMSEA] = 0.08). Allowing a correlation between physical and emotional role limitation subscales improved fit (RMSEA = 0.04). Correlations between SF-12 and SF-36 component summary scores support convergent and divergent validity although a medium effect size difference between PCS-12 and PCS-36 (Cohen's d = 0.61) was found. CONCLUSIONS: This study provides the first evidence that SF-12 is a reliable and valid measure of HrQoL in Indonesian middle-aged and older adults. The algorithm for computing SF-12 and its association with SF-36 in the Indonesian population warrant further investigation.