Editor—Gilbody et al published a systematic review of the effect in primary care settings of routinely administered questionnaires on the recognition, treatment, and outcome of psychiatric disorders, particularly depression.1 They reviewed randomised trials published throughout 2000 and concluded that the routine administration of such questionnaires is a costly exercise that has not been shown to influence clinicians' behaviour.
On behalf of the United States Preventive Services Task Force, we performed a broader systematic review of the effectiveness of routine screening for depression. In addition to those reported in Gilbody et al, we identified six randomised trials of screening that examined recognition, treatment, or clinical outcomes.2–7 Each study used a validated screening instrument and gave feedback to providers of the screening results; some also confirmed results from the screening instrument with a criterion standard or gave systematic support to providers and patients to improve the quality of care after recognition of the diagnosis or condition. Gilbody et al cited the study by Wells et al in their discussion but did not include it in their analysis; other studies were not addressed in the report. Since several of these studies had positive impact on at least one major outcome, we are concerned that not including them may have affected the conclusions of the review. Gilbody et al included one study of depression screening that we did not identify.8 Even with the addition of the extra studies, we agree with Gilbody et al that interpreting the results of these screening trials is difficult because of the heterogeneity of outcome measures and times at which outcomes were assessed. In addition, because the minimal difference in outcome rates that is considered clinically important has not been defined, the question of whether existing trials have enough power to exclude an important effect remains unclear.
Gilbody et al surmise that because the post-test probability of major depression is only 50% after a positive screen, physicians may tire of sorting out actual cases from those who would not benefit clinically. We argue, by contrast, that a 35-50% probability of major depression is quite high enough to justify the next step—namely, a diagnostic interview lasting 10 minutes. Not acting on the results of a positive screen may be related to lack of familiarity with diagnostic interviewing, lack of skill in treating depression, or failure to appreciate the morbidity associated with depressive disorders. Systematic efforts to provide additional support for treatment and follow up, as employed in the study by Wells et al, may improve the likelihood of improved outcomes.
References
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