Investigating long - term retest effects in the GHQ - 12 ISER

The aim of this analysis was to examine data from a general population sample for any retest effects in the 12-item General Health Questionnaire. A core panel was drawn from the British Household Panel Survey (n = 4749) of those who had completed the GHQ-12 seven times from 1991 to 1997. The panel results were compared with cross-sectional data from the Health Surveys for England for the same years. No evidence of retest effects was found. The age composition of the panel and the distribution of GHQ scores with age are discussed in light of these findings. Non-Technical Summary In this paper, we investigate whether or not the repeated application of the 12-item General Health Questionnaire (GHQ) results in any discernible retest effects. The GHQ has been administered to a core panel of the British Household Panel Survey (BHPS) once a year since 1991; seven times, up to and including wave 7. Other studies have found that the GHQ is liable to retest effects when administered multiple times over a short period, but it is uncertain if a longer time period between applications has similar results. Results from the BHPS core panel are compared with data from the Health Surveys for England, a series of large crosssectional studies conducted over the same years. Overall, the results indicate that no retest effects are present in the BHPS data and that the 12-item GHQ is a suitable measure of mental health for use in population based studies with relatively long time periods between applications.