Undetected depression in primary healthcare: Occurrence, severity and co-morbidity in a two-stage procedure of opportunistic screening

Background: Depression often remains undetected in primary healthcare, and a two-stage screening procedure has been recommended for future research on the recognition, management and outcome of these patients. The aim of this study was to analyse the occurrence and the severity of depression, as well as gender, age and psychiatric co-morbidity in patients with previously undetected depression using a screening questionnaire followed by a diagnostic interview for detecting depression among patients visiting primary healthcare. Methods: All patients visiting a primary healthcare centre during a period of 10 days were asked to fill in the self-rating version of the Montgomery-Asberg Depression Rating Scale. Patients with a score of 12 or more were invited to participate in a structured diagnostic interview based on the Primary Care Evaluation of Mental Disorders. Results: Out of 221 (=N) participants, 45 (20.4%) patients showed signs of depression (scores of 12 or more). Of these 45 patients, 31 consented to the structured interview, and of those, 28 (12.7%) fulfilled the criteria for depression, 17 (7.7%) had a major depression and 11 (5.0%) had a mixed depression-anxiety condition. Conclusions: The rate of undetected depression in primary healthcare was considerable. The majority of these patients had a major depression. Psychiatric co-morbidity among depressed patients was almost universal. The two-stage procedure of opportunistic screening with the Montgomery-Asberg Depression Rating Scale and the Primary Care Evaluation of Mental Disorders seems to be a feasible method for detecting these patients in primary healthcare.