MEASURING THE MENTAL-HEALTH STATUS OF A POPULATION - A COMPARISON OF THE GHQ-12 AND THE SF-36 (MHI-5)

Background. A comparison of the performance of the 5-item mental healt h dimension of SF-36 (MHI-5) with that of the 12-item General Health Q uestionnaire (GHQ-12) in a defined, non-patient population, using stan dard statistical tests. Methods. A postal survey of 3000 patients aged 16-64 years was conducted. Patients were randomly selected from the p ractice lists of two general practices chosen to represent populations with different socio-economic characteristics. Results. Considerable evidence was found for the internal consistency of both instruments (C ronbach's alpha 0.91 and 0.84 for GHQ-12 and the MHI-5 respectively) a nd for their construct validity in terms of distinguishing between gro ups with measured health differences. Both instruments showed a signif icant difference in the mean scores for men and women. In contrast to the GHQ-12, no correlation was found between age and score for the MHI -5. Both instruments were equally sensitive to socio-economic characte ristics and to levels of social support. The scores on the two instrum ents were highly correlated (Spearman rank correlation -0.73). Conclus ion. The MHI-5 has comparable psychometric performance to the GHQ-12, and can be used to measure and compare mental health in defined popula tions. Operational advantages of the MHI-5 over the GHQ-12 are that it is in the public domain, is part of a general health measure (SF-36) and is shorter.