Multiple applications of the GHQ-12 in a general population sample: an investigation of long-term retest effects

Background: Previous studies have indicated that the 60-, 30-, 28- and 12-item versions of the General Health Questionnaire (GHQ) are liable to retest effects, especially when administered multiple times with short intervals. The aim of this study was to examine data from a large general population sample for evidence of any retest effects over 7 yearly applications. Methods: A core panel was drawn from the British Household Panel Survey of those respondents who had completed the GHQ-12 seven times from 1991 to 1997 (n = 4749). The panel results were compared with cross-sectional data from the Health Surveys for England for the same years. The analyses were conducted separately for males and females broken down by age groupings. Results: No evidence of retest effects was found. For males, the panel results did not diverge significantly from the cross-sectional results. For females, the panel results did indicate a divergence from the cross-sectional results, but this was due to the age composition of the panel and differing age trajectories. Conclusion: The GHQ-12 is a consistent and reliable instrument when used in general population samples with relatively long intervals between applications.