Background. Preceding longitudinal course and current somatic and psychiatric co-morbidity of depression have been little investigated in primary care.

Method. Consecutive patients (n=1111) in primary care in the city of Vantaa, Finland, were screened for depression with the PRIME-MD, and positive cases interviewed by telephone. Cases with current depressive symptoms were diagnosed face-to-face with the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I/P). A cohort of 137 patients with unipolar depressive disorders, comprising all patients with at least two depressive symptoms and clinically significant distress or disability, was recruited. The Structured Clinical Interview for DSM-IV Axis II Disorders (SCID-II), medical records, rating scales, and a retrospective life-chart were used to obtain comprehensive cross-sectional and longitudinal information.

Results. Current major depressive disorder (MDD) was the most prevalent depressive disorder (66%); it was usually mild to moderate but recurrent. A quarter of cases (23%) had MDD in partial remission or prodromal phase, and only 10% had true minor depression. Axis I co-morbidity was present in 59%, Axis II in 52%, and chronic Axis III disorders in 47%; only 12% had no co-morbidity. One third of patients presented with a psychological complaint, predicted by higher depression severity and younger age.

Conclusion. From a lifetime perspective, the majority of primary-care patients with depressive disorders suffer from recurrent MDD, although they are currently often in prodromal or residual phase. Psychiatric and somatic co-morbidity are highly prevalent. Treatment of depression in primary care should not rely on an assumption of short-lived, uncomplicated mild disorders.