[Prevalence and characteristics of major depression and dysthymia in primary care]

To find the prevalence and characteristics of depressive disorders in patients consulting in primary care.Design. Cross-sectional descriptive study. Two stages: screening, then structured psychiatric interview.Setting. Eight clinics at four primary care centres.

A sample of 350 consecutive patients aged between 18 and 70 filled out Zung's Self-Rating Depression Scale (SDS). The diagnoses of major depressive episode and dysthymia for the 138 with positive result and the 67 with negative result were investigated through the Structured Clinical Interview for DSM-IV Axis I Disorders. Measurements and main results. We found a weighted prevalence of 14.7% (95% CI: 10.7-18.7) for major depression and 4.6% (95% CI: 2.4-6.8) for dysthymia. Mean score on the SDS was 65.6 (SD 11.6) in the group with major depression and 63.3 (SD 8.7) in the group with dysthymia. Mean score in the not-depressed group was 44.2 (SD 8.7), lower than the scores for both groups with depression (p < 0.0001). Being female distinguished the depressed groups from the not-depressed group. Lower educational level and the amount of over-users distinguished the group with major depression from the not-depressed group. The symptom profiles were virtually identical for the two depressed groups, whereas the frequency of occurrence of most of the symptoms explored differed significantly between those with and without depression.

Prevalence of major depression and dysthymia are high in primary care patients in our area. Both disorders have common characteristics of demographic variables and symptom profile.