"Patient knows best"---detection of common mental disorders in Santiago, Chile: cross sectional study Commentary: Clinical practice is as important as diagnosis

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Abstract
Methods and resultsWe studied 815 consecutive patients seen by 11 primary care physicians from five randomly selected clinics in northern Santiago, Chile. Patients with a chronic illness or patients aged over 50 were excluded because these patients are better known by doctors. Most doctors in Chile and in this study have less than four years' experience in primary care.Before the patient saw the doctor, a lay interviewer asked the patient's reason for consultation and whether it was because of a physical or psychological problem. The interviewer inquired about other potential confounders: physical illness, disability, common somatic symptoms, and whether patients tended to interpret common somatic symptoms by using psychological, physical, or normalising explanations.A psychiatrist administered the clinical interview schedule—revised, and patients scoring 12 or more were classified as having a common mental disorder.5 After the patient had seen the primary care physician, the doctor rated blindly whether the patient had a mental disorder using a five-point scale. Patients with a rating of “mild or greater” severity were considered to have a mental disorder.The prevalence of mental disorders was 49% (396 of 802; 95% confidence interval 46% to 53%) according to the clinical interview schedule—revised and 35% (276 of 796; 31% to 38%) according to the doctors' ratings. Agreement of doctors' ratings was 48% (186 of 385; 43% to 53%) with the psychiatric assessment (κ=0.27), so 52% (199 of 385; 47% to 57%) of the cases identified by the clinical interview schedule went undetected. As a whole, 34% (269 of 795; 30% to 37%) of the patients chose a psychological explanation for their reason for consultation but only 69% (185 of 269; 63% to 74%) of them were psychiatric cases according to the psychiatric interviewer.View this table: In this window In a new window The association between patients' causal attribution (physical or psychological) of the reason for consultation and the detection of common mental disorders by primary care doctors. Only cases diagnosed according to psychiatric interview are includedWhen analysis was restricted to psychiatric cases, almost half (48%) (186 of 389; 43% to 53%) of these patients attributed their reason for consultation to psychological causes. Among psychiatric cases, doctors identified correctly 34% (70 of 204; 28% to 41%) of those who attributed their reason for consultation to physical causes and 63% (116 of 185; 55% to 70%) of those who attributed their presenting problems to a psychological cause. After adjustment for confounders three variables showed significant independent associations with detection (table): a spontaneous psychological reason for consultation, a psychological causal attribution for the presenting problems, and an increased severity of the mental disorder.AcknowledgmentsSCDC is a member of the MaGPIe (Mental Health and General Practice Investigation) research group, a collaboration between the departments of general practice, psychological medicine, and public health at the Wellington School of Medicine, University of Otago, New Zealand.