General practitioner recognition of mental illness in the absence of a 'gold standard'

Abstract

Objective: To compare general practitioner (GP) recognition of mental illness with cases identified by screening and diagnostic instruments.

Method: Cross-sectional survey (part of the Mental Health and General Practice Investigation [MaGPIe] study) set in the lower North Island of New Zealand. The study sample consisted of consecutive patients from a random sample of GPs who were screened using the General Health Questionnaire (GHQ-12). Based on GHQ scores a stratified random sample of patients was selected and invited to participate in an in-depth interview to assess their psychological health and a subsequent longitudinal study. GPs assessed patients' psychological health using a 5-point scale of severity. Patients completed the GHQ-12, Composite International Diagnostic Interview (CIDI), Somatic and Psychological Health Report (SPHERE-12) and World Health Organization's Disability Assessment Schedule Version II (WHODAS).

Results: Seventy GPs (90% response) and 775 patients (70% response) were included in analyses. Overall, GPs recognized symptoms of psychological disorders in the past 12 months in 56.4% (95% CI=49.3-63.5) of patients. Agreement between GP rates of recognition of mental disorders and diagnostic or symptom rating instruments varied depending on the instruments used and was highest when there was concordance between several instruments and high levels of disability. Only 17.2% (95% CI=14.5-19.9) of the patients identified by at least one of the GHQ-12, CIDI or SPHERE, were identified by all three instruments.

Conclusions: In understanding rates of recognition of mental disorders by GPs, careful consideration needs to be given to the degree to which any single instrument can be utilized as a diagnostic 'gold standard'.