[Comorbidity of major depression with other common mental disorders in primary care patients].

INTRODUCTION: Psychiatric comorbidity affects the impact, the prognosis and the management of depression. AIMS: To determine the prevalence of other common mental disorders in patients with major depression and to analyse their associated comorbidities.
DESIGN: Two-stage cross-sectional study: a) screening (Zung's Self-Rating Depression Scale); b) a standardised psychiatric interview. SETTINGS: Ten health centres in the province of Tarragona. PATIENTS: A total of 906 consecutive patients were screened. In the second stage, the 209 patients who gave a positive result and 97 patients who gave a negative result (1/7 at random) were evaluated. ANALYSIS: The statistical analysis used weights that took into account the two-stage sampling. The frequency with which dysthymia, generalised anxiety disorder, panic disorder and somatisation disorder presented concomitantly with major depression was determined. The characteristics of the depressed patients were compared for different degrees of comorbidity.
RESULTS: In 45.7% (95% CI, 32.8-59.2) of patients with major depression there was one other coexisting mental disorder, in 19.9% (95% CI, 13.7-27.9) two more mental disorders and in 8.3% (95% CI, 4.5-14.8) three more mental disorders. Generalised anxiety disorder was present in 55.2% of depressed patients (95% CI, 41.6-68), panic disorder in 33.8% (95% CI, 21.1-47.1), dysthymia in 15.7% (95% CI, 10.3-23.4) and somatisation disorder in 6.6% (95% CI, 3.3-12.8). In the groups of patients with comorbidity, the depression was more severe and had a greater functional impact. There were no differences in the clinical management variables.
CONCLUSIONS: Psychiatric comorbidity of depression is common in primary care. Most depressed patients suffer from other disorders, often anxiety.