Validity and reliability of the Medical Outcomes Study Short-Form Health Survey version 2 (SF-12v2) among adults with autism.

BACKGROUND: The purpose of the study was to assess the validity and reliability of the Medical Outcomes Study Short Form-12 version 2 (SF-12v2) instrument among adults with autism.

METHODS: Study data was collected using a cross-sectional online survey of adults with autism enrolled with the Interactive Autism Network (N=291). Factorial validity was assessed using confirmatory factor analysis technique. Item-scale correlations were examined for convergent validity. Known-groups validity was assessed by examining the variation in Physical Component Summary (PCS) and Mental Component Summary (MCS) scores by autism severity. Cronbach's alpha was determined for internal consistency reliability. Floor and ceiling effects were also assessed.

RESULTS: A two-factor model with correlated error terms was found to have a good fit. The PCS scale strongly correlated with the underlying items representing the scale. The MCS scale had strong to moderate correlation with its underlying items. For known-groups validity, the MCS score varied as expected with lower score observed among adults with high severity as compared to low severity; however, PCS score varied inversely. Internal consistent reliability of the SF-12v2 was good, and there were no floor and ceiling effects.

CONCLUSIONS: Except for known-groups validity, all other psychometric indicators performed well for the SF-12v2.