Screening for Depression in Adults: A Summary of the Evidence for the U.S. Preventive Services Task Force

Depressive disorders are common, chronic, and costly. Prevalence rates from community-based surveys range from 1.8% to 3.3% for depression within the past month and 4.9% to 17.1% for lifetime prevalence (1, 2). In primary care settings, the point prevalence of major depression ranges from 4.8% to 8.6% (3). Depressive illness is projected to be the second leading cause of disability worldwide in 2020 (4). The substantial public health and economic significance of depression is reflected by its considerable effect on health care utilization and great monetary costs: $43 billion annually, of which $17 billion represents lost work days (5, 6). Despite the high prevalence and substantial impact of depression, detection and treatment in the primary care setting have been suboptimal. Studies have shown that usual care by primary care physicians fails to recognize 30% to 50% of depressed patients (7). Because patients in whom depression goes unrecognized cannot be appropriately treated, systematic screening has been advocated as a means of improving detection, treatment, and outcomes of depression. In 1996, the U.S. Preventive Services Task Force found insufficient evidence to recommend for or against routine screening for depression with standardized questionnaires (8). The Task Force recommended that clinicians maintain an especially high index of suspicion for depressive symptoms in adolescents and young adults, persons with a family or personal history of depression, those with chronic illnesses, those who perceive or have experienced a recent loss, and those with sleep disorders, chronic pain, or multiple unexplained somatic complaints (8). It also recommended physician education in recognizing and treating depression. To help determine whether systematic, routine screening for depression in adults is warranted, we performed an updated systematic review for the U.S. Preventive Services Task Force. Specifically, we examined three key questions: 1) What is the accuracy of case-finding instruments for depression in primary care populations? 2) Is treatment of depression in primary care patients effective in improving outcomes? 3) Is routine systematic identification with case-finding questions (screening), with or without integrated management and follow-up systems, more effective than usual care in identifying patients with depression, facilitating treatment of patients with depression, and improving clinical outcomes? The results of the comprehensive review are available from the Agency for Healthcare Research and Quality (www.ahrq.gov/clinic/uspstfix.htm) (9). In brief, we found that several short, accurate, and easy-to-use instruments for detecting depression are available (9, 10) (Table 1). Brief instruments, including asking the patient two questions about the presence of depressed mood and anhedonia (Over the past 2 weeks, have you felt down, depressed or hopeless? and Over the past 2 weeks, have you felt little interest or pleasure in doing things? ), appear to perform as well as longer instruments. Effective treatments, including pharmacologic and behavioral or counseling interventions, are available for depressed patients identified in primary care settings (9). Table 1. Characteristics of Case-Finding Instruments Used To Detect Depression in Adults in Primary Care Settings We also examined the evidence on whether screening for depression in primary care settings affects recognition, treatment, and clinical outcomes of adult patients with depression. In this article, we review the evidence pertaining to this overarching question. Methods To identify relevant articles, we searched the MEDLINE database from January 1994 through August 2001 by using the Medical Subject Headings depression or depressive disorders, plus keyword searches for commonly used screening instruments. These terms were then combined with the Medical Subject Headings mass screening or sensitivity and specificity or primary health care or ambulatory care or family practice. We supplemented these sources by searching the Cochrane database on depression, neurosis, and anxiety disorders; performing additional specific MEDLINE searches from 1966 to 1994; hand searching bibliographies; and querying experts. We reviewed randomized trials conducted in primary care settings that examined the effect of screening for depression on identification, treatment, or health outcomes, including trials that tested integrated, systematic support for treatment after identification of depression. Two of the authors independently reviewed the titles and abstracts of the articles identified by the literature searches and excluded ones on which they agreed that eligibility criteria were not met. When the initial reviewers disagreed, the articles were carried forward to the next review stage in which the investigators reviewed the full articles and made a final decision about inclusion or exclusion by consensus. One reviewer abstracted the relevant information from each article into evidence tables. A second author checked these tables and noted discrepancies, which were then resolved by consensus. We calculated absolute differences in outcomes and 95% CIs by using Stata software, version 6.0 (Stata Corp., College Station, Texas), when these results were not presented in the original articles. To summarize the effect of screening on clinical outcomes, we performed meta-analysis by using RevMan software (Cochrane Collaboration, 2000) and the DerSimonian and Laird random-effects model. This evidence report was funded through a contract to the Research Triangle InstituteUniversity of North Carolina Evidence-based Practice Center from the Agency for Healthcare Research and Quality. Staff of the funding agency contributed to the study design, reviewed draft and final manuscripts, and made editing suggestions. Results The effect of routine screening of adult patients for depression in primary care was compared with usual care in 14 randomized trials in primary care settings (11-25). The main outcomes examined were differences in providers' rate of detection or recognition of depression, the proportion of patients with depression who were treated or referred for treatment, and clinical outcomes of depression. The screening interventions differed in intensity. Some trials provided feedback of screening results alone; others provided feedback and general or specific treatment advice to the providers; and some provided feedback and treatment advice and helped practices develop systematic means of improving the quality of treatment and follow-up. The trials, which were stratified by intensity of the intervention, are described below and summarized in Tables 2, 3, 4, and 5. Table 2. Studies on the Effect of Screening and Feedback Table 3. Summary of the Effect of Feedback from Screening on Rates of Diagnosis Table 4. Summary of the Effect of Feedback from Screening on Rates of Treatment Table 5. Summary of the Effect of Feedback from Screening on Patient Outcomes Effects of Screening and Feedback Alone Johnstone and Goldberg applied the self-administered General Health Questionnaire to 1093 primary care patients and identified 119 with depression (14). These 119 patients were randomly assigned to immediate feedback of the results to the physician or to usual care. The groups did not differ significantly in mean General Health Questionnaire scores at 12-month follow-up, except for the subgroup of patients with severe depression, for whom feedback improved scores. Among all patients, the total amount of time spent depressed within 1 year decreased by approximately 2 months (P < 0.01). Three trials evaluated feedback of Zung Self-Depression Scale scores to providers. Moore and colleagues asked 212 consecutive patients 20 to 60 years of age who attended a university-based family medicine residency clinic to self-administer the Zung Self-Depression Scale (15). The 96 patients who scored higher than 50 were randomly assigned to a group whose providers were given immediate written feedback of results or to a group whose providers received a generic note saying that their patients had been screened. The same note was affixed to the charts of patients in each group who had scored 50 or less. Recognition of depression, as assessed by chart audit, was 56% in the intervention group (28 of 50 patients) and 22% in the control group (10 of 46 patients). Prescription of treatment was not assessed. Linn and Yager tested immediate written feedback of Zung Self-Depression Scale results compared with no screening in 74 consecutive new patients from a primary care clinic, using chart audit to assess outcomes (16). Depression was more likely to be diagnosed in patients assigned to the feedback group than in those receiving usual care (29% vs. 8%); treatment rates were low and similar in each group (13% vs. 8%). Neither Moore and colleagues nor Linn and Yager reported clinical outcomes. Magruder-Habib and associates screened 800 Veterans Administration patients for depression in a primary care clinic (18). Research assistants administered the Zung Self-Depression Scale and used the Diagnostic Interview Schedule to confirm diagnosis according to criteria from the Diagnostic and Statistical Manual of Mental Disorders, third edition (DSM-III) (18, 26). The 100 patients who screened positive (excluding those with scores higher than 75 or history of depression) and met DSM-III criteria for major depression were randomly assigned to feedback of screening results or usual care; chart audit was used to assess outcomes. Patients whose physicians received feedback were three times more likely to be accurately identified as depressed at the index visit than were patients whose clinicians had not received such feedback (25% vs. 8%; difference, 17 percentage points [CI, 3 to 32 percentage points]). At 1 year of follow-up, 42% of the intervention group and 21% of the control group had been recognized as depresse