Multi-item scales for measuring global self-rated health - Investigation of construct validity using structural equations models

The authors used multigroup confirmatory factor analysis and structural equ ations models to examine the construct validity and item functioning of the five-item General Health (GH) scale from the SF-36 in Danes over 16 years of age (n=4,084). They included four criteria variables for physical and me ntal health. Items GH2-GH5 had low response rates among the elderly, probab ly due to the compact layout of these items in the questionnaire. The autho rs found differential item functioning for several items, indicating some d egree of multidimensionality in the GH scale. Thus, GH1 had stronger associ ations with age, physical functioning, and chronic diseases than predicted by the one-factor model. However, psychometrical problems were mostly found in the youngest age group. If the problem of missing values is solved by l ayout changes or interview administration, the GH scale appears to be a val id measure of self-rated health in elderly populations.