Course and outcome of depressive disorders in primary care: a prospective 18-month study

Depressive disorders are known to often be chronic and recurrent both in the general population and in psychiatric settings. However, despite its importance for public health and services, the outcome of depression in primary care is not well known.

In The Vantaa Primary Care Depression Study (PC-VDS), 1111 consecutive primary-care patients were screened for depression with the Prime-MD screen, and 137 diagnosed with DSM-IV depressive disorders by interviewing with the Structured Clinical Interview for DSM-IV (SCID)-I/P and SCID-II. This cohort was prospectively followed-up at 3, 6 and 18 months. Altogether 123 patients (90%) completed the 18-month follow-up, including 79 with major depressive disorder (MDD) and 44 with subsyndromal disorders. Duration of the index episode and the timing of relapses/recurrences were examined using a life-chart.

Of the patients with MDD, only a quarter [25% (20/79)] achieved and remained in full remission, while another quarter [25% (20/79)] persisted in major depressive episode for 18 months. The remaining 49% (39/79) suffered from residual symptoms or recurrences. In Cox regression models, time to remission and recurrences were robustly predicted by severity of depression, and less consistently by co-morbid substance-use disorder, chronic medical illness or cluster C personality disorder. Of the subsyndromal patients, 25% (11/44) proceeded to MDD.

This prospective medium-term study verified the high rate of recurrences and chronicity of depression also in primary care. Severity of depressive symptoms and co-morbidity are important predictors of outcome. Development of chronic disease management for depression is warranted in primary care.