Construct validity of the 12-item Short Form Health Survey (SF-12) version 2 and the impact of lifestyle modifications on the health-related quality of life among Indian adults with prediabetes: results from the D-CLIP trial

Purpose This study aimed to validate the factor structure of the 12-item Short-Form (SF-12) health-related quality of life (HRQOL) survey for Indian adults and assess the impact of lifestyle modification on the SF-12 of Indian adults with prediabetes. Methods To validate the context-specific construct of the SF-12, two-factor confirmatory factor analysis (CFA) was performed using data from 1285 adults residing in Chennai, India, who screened for the Diabetes Community Lifestyle Improvement Program (D-CLIP). D-CLIP was a randomized controlled trial of 578 participants with prediabetes (283 treatment, 293 control), focusing on the effect of lifestyle modifications on the prevention of diabetes. Physical and mental component scores (PCS and MCS) were computed by using CFA standardized factor loadings. Multiple linear regression was subsequently conducted to estimate the effect of lifestyle modification on post-study changes of PCS and MCS among D-CLIP participants. Results Cronbach’s alpha and CFA fit indices demonstrated acceptable reliability and model fit of the SF-12 for Indian adults. The intervention group showed greater mean change in PCS after study participation compared to the controls (1.63 ± 0.82, p = 0.046); no significant difference was observed for MCS between two groups (1.00 ± 0.85, p = 0.242). Conclusion The study confirmed that the SF-12 is suitable for assessing the physical and mental health dimensions of HRQOL for Indian adults. Our findings suggest that the benefits of diabetes prevention lifestyle modification strategies may primarily enhance the physical well-being of adults with prediabetes. Further studies validating the SF-12 in a broader Asian Indian population are needed. Trial registration Clinicaltrials.gov, NCT01283308.