Comparison between the GHQ-28 and SF-36 (MH 1–5) for the assessment of the mental health in patients with ischaemic heart disease

Objective: To assess the mental health of patients admitted to hospital with suspected ischaemic heart disease, by means of two instruments, the General Health Questionnaire (GHQ-28) and the MH (1–5) dimension of the SF-36 Health Survey Questionnaire, and to compare the psychometric properties of both questionnaires in this population. Methods: A study was conducted of 185 patients consecutively admitted to hospital with suspected ischaemic heart disease, classified into four groups: Acute Myocardial Infarctus (AMI), unstable angina, non-ischaemic cardiologies, and non-cardiological conditions. Their mental health was assessed by means of the GHQ-28 and the MH 1–5 sub-scales of the SF-36; the validity of the results were analysed by the association of each instrument with socio-demographic (age, sex, social class, and educational level) and clinical (co-morbidity, risk factors, diagnostic groups and background to the illness) variables. The correlation of each instrument with other sub-scales of the SF-36 was studied. The internal consistency was measured by Cronbach's α, together with the item-internal consistency and item-discriminant validity. Results: Of the population studied, 71.9% were males and the mean age was 60.2 years (SD: 10.4). The diagnosis for 33.5% was AMI and for 37.8% unstable angina. For all the variables studied, the scores in the two instruments were ordered in the same way, and were significantly worse for females and for the most disadvantaged social class. None of the scales discriminated in respect of the diagnostic group or the presence of comorbidity. However, a linear relationship was observed with risk factors. Cronbach's α was 0.95 for the GHQ-28 and 0.80 for the MH 1–5. Correlations with the other dimensions showed ranges of −0.35 to −0.61 for the GHQ-28 and of 0.26 to 0.61 for the MH 1–5. These were highest for the Vitality and Social Functioning sub-scales in both instruments. Conclusions: The subjective perception of mental health is measured in a similar way by both the MH 1–5 scale of the SF-36 and the GHQ-28. However, since the MH 1–5 questionnaire is shorter, it should be administratively easier to introduce into routine cardiological practice.