The 60-item General Health Questionnaire was completed by 90% of 4798 patients aged 15–69 years who consulted, on one day, the general practitioners of 97% of practices in the Perth Statistical Division. A point prevalence rate of minor psychiatric morbidity in various demographic groups was calculated in terms of the population at risk. The demographic pattern of morbidity was compared with that found in a probability sample of 2324 community residents drawn from the same population at risk, and surveyed at the same time using the same screening instrument.
Widowed persons, British-born men who had recently migrated to Australia, and lower-social-class men with minor psychiatric morbidity were under-represented in general practice. Elderly men and women in upper-class occupations with minor psychiatric morbidity were over-represented in general practice. These differences, unlike others that were found, could not be explained by differing consulting habits or by differing completion rates of the screening instrument.