Assessment of psychological morbidity in primary care: explorations with the General Health Questionnaire.

The 30-item version of the General Health Questionnaire (GHQ) was completed by 1649 new adult enrollees in a Health Maintenance Organization (HMO). Factor analysis of responses disclosed six factors (Anxiety/Strain, Confidence, Depression, Energy, Social Function, and Insomnia) and a strong tendency for items of similar wording (positive phrasing) to cluster together. Elevations of GHQ scores, especially when persistent over two administrations of the GHQ separated by 7 months, were strongly associated with the probability of both mental health and non-mental health care within 12 months of enrollment. Anxiety/Strain, Depression, and Social Function scores were associated with the probability of use; Confidence and Energy factors were not. Once in care a member's rate of use of service was relatively independent of the response pattern to the GHQ at enrollment.