Are screening tools for depression effective in primary care practice?
Sensitive and specific screening tools and effective treatments are available for depression. However, screening for depression has not been shown to increase the number of patients who receive treatment or to improve patient outcomes. This may be because the positive predictive values of screening tests for depression are lower in primary care, or because physicians already are adept at identifying those patients most likely to benefit from treatment (i.e., those who have the most severe symptoms and the greatest functional limitations).
There is evidence to suggest that depression is underrecognized in primary care and that patients who are depressed use health care resources more frequently. Therefore, improving care for patients with depression has the potential to improve outcomes and lower costs. A number of validated screening tools have been developed to identify patients with depression in primary care, but research has found mixed results on clinical outcomes.1 In 2002, the U.S. Preventive Services Task Force (USPSTF) found at least fair evidence to recommend that adults should be screened for depression in clinical practices that have systems in place to ensure accurate diagnosis, effective treatment, and follow-up.2 Clinical outcomes are better when the screening is followed up with treatment. The USPSTF did not find data to help physicians design effective diagnosis, treatment, and follow-up procedures.
Gilbody and colleagues revisited this topic in 2005. They searched the literature for randomized controlled trials of screening instruments for depression in primary care settings and found 12 studies with a total of 5,693 patients. Overall, they found that using a screening instrument only slightly increased the detection of depression (relative risk, 1.38; 95% confidence interval, 1.04 to 1.83). However, the results were heterogeneous. There was an insignificant trend toward increased intervention when screening instruments were used. Furthermore, three out of four studies showed patients who were screened had no difference in clinical outcome. No studies on cost-effectiveness were found. It is possible that an enhanced model of care for follow-up on screening results may improve outcomes. However, no studies included follow-up with enhanced models of care such as case management or collaborative care.
Until models of care are developed that improve health care outcomes for patients with depression, family physicians should spend their limited time on other interventions. Unstructured observation by physicians may be sufficient to identify those patients with significant functional limitations who will benefit the most from treatment.