Validation of the 12 Item Short form Health Survey in a Sample from Region Central Jutland

Abstract

In 2010 the Danish regions started a new program of public health surveillance in collaboration with the national and local health authorities using the short form health survey (SF-12) for measuring and reporting on health related quality of life among the Danish adult population. The instrument has not, however, been validated in a Danish setting. The aim of this study was to assess the reliability and validity of the physical component summary (PCS) and the mental component summary (MCS) score of the 12-item short form health survey (SF-12) in a sample from Central Denmark Region. A total of 26,397 persons above the age of 25 were included in the analyses. Reliability was assessed by Cronbach’s α. The validity was assessed using known-groups comparisons and convergent validity. The factor structure was investigated through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). The Cronbach’s α showed high reliability with a score of 0.90 and 0.85 for PCS and MCS respectively. The SF-12 discriminated well with respect to gender, age, educational status and long term illness. Individual items correlated higher with own hypothesized scales than with other scales and summary measures corroborating the convergent validity. The EFA gave a two-factor structure. Irrespective of the chosen rotation method (varimax and oblimin) the items related to PCS loaded on one factor and the items related to MCS loaded on another factor. The factor structure was validated with acceptable model-fit values in CFA. The SF-12 instrument is a reliable and valid measure of health related quality of life among the population of Central Denmark Region.