Comparing the SF-36 and SF-12 in Psychometric Properties as Measuring Quality of Life among Adolescent in China: a Large Sample Cross-sectional Study

Abstract

Objective: By comparing psychometric properties of the SF-36 and the SF-12, supplied evidence for the election of instruments of the quality of life (QOL) and decision-making processes to promote the Quality of Life of adolescent. Methods: Stratified cluster random sampling was adopted. The Short-Form 36 (SF-36) was used to assess QOL. Pearson Correlation Coefficient was used to show correlation. Cronbach’s Alpha and Construct Reliability (CR) were used to evaluate reliability of SF-36 and the Short-Form 12 (SF-12), Criterion Validity and Average Variance Extracted (AVE, Convergence Validity) for validity. Confirmatory factor analysis was used to calculate load factor for each item, then obtained CR and AVE. The Semejima grade response model (Logistic two-parameter module) in the item response theory was used to estimate the Item Discrimination, Item Difficulty and Item Average Information of each item. Results: 19,428 samples were included in the study. The mean age was 14.78 years (SD=1.77). High correlations between corresponding domains and components of both scales were found. Reliability of sf-36 each domain was better than that corresponding domain of sf-12. Domains of PF, RP, BP, and GH in SF-36 had good construct reliability (CR,>0.6). The Criterion Validities of SF-36 were little higher in some corresponding dimensions except PCS. Convergence validities of SF-12 were higher than SF-36 in PF, RP, BP and PCS. The items of BP, SF, RP and VT in SF-12 had acceptable discriminations of items and higher than in SF-36. The items Average Amounts of Information of BP, VT, SF, RE and MH in SF-36 and SF-12 were poor. Conclusion: Two components (PCS and MCS) measurements of SF-12 appeared to perform at least as well as the SF-36 in cross-sectional settings in adolescence. Some domains, for instance SF and BP, were suitable for adolescents or not need study further.