USE OF STRUCTURAL EQUATION MODELING TO TEST THE CONSTRUCT-VALIDITY OFTHE SF-36 HEALTH SURVEY IN 10 COUNTRIES - RESULTS FROM THE IQOLA PROJECT

A crucial prerequisite to the use of the SF-36 Health Survey in multin ational studies is the reproduction of the conceptual model underlying its scoring and interpretation. Structural equation modeling (SEM) wa s used to test these aspects of the construct validity of the SF-36 in ten IQOLA countries: Denmark, France, Germany, Italy, the Netherlands , Norway, Spain, Sweden, the United Kingdom, and the United States. Da ta came from general population surveys fielded to gather normative da ta. Measurement and structural models developed in the United States w ere cross-validated in random halves of the sample in each country. SE M analyses supported the eight first-order factor model of health that underlies the scoring of SF-36 scales and two second-order factors th at are the basis for summary physical and mental health measures. A si ngle third-order factor was also observed in support of the hypothesis that all responses to the SF-36 are generated by a single, underlying construct-health In addition, a third second-order factors, interpret ed as general well-being, was shown to improve the fit of the model. T his model (including eight first-order factors, three second-order fac tors, and one third-order factor) was cross-validated using a holdout sample within the United States and in each of the nine other countrie s. These results confirm the hypothesized relationships between SF-36 items and scales and justify their scoring in each country using stand ard algorithms. Results also suggest that SF-36 scales and summary phy sical and mental health measures will have similar interpretations acr oss countries. The practical implications of a third second-order SF-3 6 factor (general well-being) warrant further study. (C) 1998 Elsevier Science Inc.