JW Williams Jr., CD Mulrow, E Chiquette, C Aguilar, PH Noel, J Cornell. South Texas Veterans Health Care System, and the San Antonio Cochrane, and Evidence-Based Practice Centers.

Purpose: Primary care physicians prescribe the majority of pharmacotherapy for depressed patients. However, the evidence for drug therapy has been developed predominantly in psychiatric settings that differ significantly with respect to the providers' training and patient characteristics. To better understand the evidence for treatment in primary care, we conducted a literature synthesis of primary care based antidepressant treatment trials.

Methods: English and non-English trials were identified from the Cochrane Collaboration Depression Anxiety and Neurosis Group's specialized registry of 8,451 clinical trial articles, references from 34 meta-analyses, and experts. Selection criteria were: depressed study population recruited and treated in the primary care setting, randomized-controlled design including one of 32 selected newer antidepressants, and intervention lasting 6 weeks. Selected articles were abstracted by 2 independent reviewers. Outcomes were combined using a random effects model.

Results: 27 trials involving 5,540 patients were identified; 4 involved comparisons between drug and placebo. All trials studied acute phase treatment; there were no augmentation or relapse prevention studies and no trials comparing antidepressant medication to psychotherapy. Tested drugs included selective serotonin re-uptake inhibitors (SSRI), newer monamine oxidase inhibitors, and dopaminergic agents. Depressive disorders studied were: major depression (n=14); depression "requiring treatment" (n=6); dysthymia (n=3); mixed anxiety depression (n=2); and trials including >1 disorder (n=2). 26 trials were conducted in Europe; 1 in the U.S. Of the 20 trials with an identified funding source, all were sponsored by pharmaceutical companies. 25 of 27 trials were double-blind but few described the interaction between the treating physician and subject. Treatment duration was 6-8 weeks (n=21), 12 weeks (n=4), and 20-24 weeks (n=2). There were sufficient trials (n=6) comparing SSRI to tricyclic antidepressants (TCA) for summary comparisons. Average response rates for both groups were approximately 60%. These comparisons showed no difference in efficacy between SSRI and TCA.

Conclusions: In head to head comparisons, SSRI and TCA have equal efficacy in primary care. However, there are significant gaps in the literature on the primary care treatment of depression including few placebo controlled trials, few trials in non-major depression, no trials comparing newer pharmacotherapies to psychotherapy, and no trials of relapse prevention.

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