The diagnosis of depression in different clinical settings. An analysis of the literature on the dexamethasone suppression test.

Overview

The dexamethasone suppression test (DST) has performed well as a diagnostic test for depression in many specialized research settings. Clinical epidemiological methodology enables prediction of its diagnostic value in a variety of clinical settings different from those in which the DST has been studied. We reanalyzed the published data on the test's performance as a confirmatory diagnostic test for endogenous depression or major depressive disorder and modeled target populations, taking into consideration available data on the epidemiology of depression and variations in the test's performance according to clinical characteristics of the patients evaluated. The problems with which patients present in different settings will contribute to lower prevalence of the disorder and lower sensitivity and specificity of the test on general psychiatry wards, in psychiatric office practices, and in medical outpatient departments. As a result, the positive predictive value of the test, which is high on research wards (92 per cent), is likely to be lower on general psychiatric wards (82 per cent) and much lower in psychiatric office practice (52 per cent) and in general medical settings (29 per cent). Clinicians who use the DST in the diagnosis of depression should be aware of clinical and epidemiological variables that will affect its diagnostic value in different settings.