Why GHQ threshold varies from one place to another

Abstract

The GHQ threshold is partly determined by the prevalence of multiple diagnoses, with higher thresholds being associated by higher rates of both single and multiple diagnosis. The mean GHQ score for the whole population of respondents provides a rough guide to the best threshold. In those centres where the discriminatory power of the GHQ is lowest, it is necessary to use a low threshold as a way of ensuring that sensitivity is protected, but the positive predictive value of the GHQ is then lower. Some of the variation between centres is due to variation in the discriminatory power of different items.