- Top of page
OBJECTIVE: To determine the effect of case-finding for depression on frequency of depression diagnoses, prescriptions for antidepressant medications, prevalence of depression, and health care utilization during 2 years of follow-up in elderly primary care patients.
DESIGN: Randomized controlled trial.
SETTING: Thirteen primary care medical clinics at the Kaiser Permanente Medical Center, an HMO in Oakland, Calif, were randomly assigned to intervention conditions (7 clinics) or control conditions (6 clinics).
PARTICIPANTS: A total of 2,346 patients aged 65 years or older who were attending appointments at these clinics and completed the 15-item Geriatric Depression Scale (GDS). GDS scores of 6 or more were considered suggestive of depression.
INTERVENTIONS: Primary care physicians in the intervention clinics were notified of their patients' GDS scores. We suggested that participants with severe depressive symptoms (GDS score ≥ 11) be referred to the Psychiatry Department and participants with mild to moderate depressive symptoms (GDS score of 6 –10) be evaluated and treated by the primary care physician. Intervention group participants with GDS scores suggestive of depression were also offered a series of organized educational group sessions on coping with depression led by a psychiatric nurse. Primary care physicians in the control clinics were not notified of their patients' GDS scores or advised of the availability of the patient education program (usual care). Participants were followed for 2 years.
MEASUREMENTS AND MAIN RESULTS: Physician diagnosis of depression, prescriptions for antidepressant medications, prevalence of depression as measured by the GDS at 2-year follow-up, and health care utilization were determined. A total of 331 participants (14%) had GDS scores suggestive of depression (GDS ≥ 6) at baseline, including 162 in the intervention group and 169 in the control group. During the 2-year follow-up period, 56 (35%) of the intervention participants and 58 (34%) of the control participants received a physician diagnosis of depression (odds ratio [OR], 1.0; 95% confidence interval [CI], 0.6 to 1.6; P = .96). Prescriptions for antidepressants were received by 59 (36%) of the intervention participants and 72 (43%) of the control participants (OR, 0.8; 95% CI, 0.5 to 1.2; P = .3). Two-year follow-up GDS scores were available for 206 participants (69% of survivors): at that time, 41 (42%) of the 97 intervention participants and 54 (50%) of the 109 control participants had GDS scores suggestive of depression (OR, 0.7; 95% CI, 0.4 to 1.3; P = .3). Comparing participants in the intervention and control groups, there were no significant differences in mean GDS change scores (−2.4 ± SD 3.7 vs −2.1 SD ± 3.6; P = .5) at the 2-year follow-up, nor were there significant differences in mean number of clinic visits (1.8 ± SD 3.1 vs 1.6 ± SD 2.8; P = .5) or mean number of hospitalizations (1.1 ± SD 1.6 vs 1.0 ± SD 1.4; P = .8) during the 2-year period. In participants with initial GDS scores > 11, there was a mean change in GDS score of −5.6 ± SD 3.9 for intervention participants (n= 13) and −3.4 ± SD 4.5 for control participants (n = 21). Adjusting for differences in baseline characteristics between groups did not affect results.
CONCLUSIONS: We were unable to demonstrate any benefit from case-finding for depression during 2 years of follow-up in elderly primary care patients. Studies are needed to determine whether case-finding combined with more intensive patient education and follow-up will improve outcomes of primary care patients with depression.
Depression is a common, serious, and treatable disease that causes substantial morbidity in primary care patients. 1,2 Particularly in the elderly, depression leads to greater medical illness, disability, functional decline, and mortality. 3–6 Depression meets most criteria for case-finding. It is a common disease with significant morbidity, the cost and risk of case-finding are low, and effective therapy is available. But whether early detection and treatment improves the outcomes of depressed patients is unclear. 7–12 Neither the U.S. Preventive Services Task Force nor the Canadian Task Force on the Periodic Health Examination has found sufficient evidence to recommend the routine use of case-finding questionnaires for depression in primary care patients. 13,14
To determine the effect of case-finding for depression, using a previously validated questionnaire, on frequency of depression diagnoses, prescriptions for antidepressant medications, prevalence of depression, and health care utilization in elderly primary care patients, we randomly assigned 13 primary care clinics at the Kaiser Permanente Medical Center in Oakland, Calif, to intervention or control conditions. Intervention clinic physicians were notified of their patients' scores on a case-finding instrument for depression; control clinic physicians were not notified of their patients' scores. Participants were followed for 2 years.
- Top of page
We found that informing primary care physicians about the results of a case-finding instrument for depression did not affect the frequency of depression diagnoses, prescriptions for antidepressant medications, the prevalence of depression, or health care utilization in elderly patients. Regardless of whether physicians were informed of patients' scores on the case-finding instrument for depression, approximately half of depressed elderly patients still had GDS scores suggestive of depression 2 years later.
Our findings support the results of 3 randomized trials 8,9,12 and 4 observational studies. 7,10,11,25 In one trial, 8 physicians of patients in the intervention group were informed that their patients had high depression scores; physicians of patients in the control group were not so informed. In a second trial, 9 physicians of intervention patients were given patient-specific treatment recommendations, and 3 special visits were scheduled to address the patients' symptoms of depression; control patients received usual care. Neither of these studies found any difference in mean depression scores at follow-up between intervention and control groups.
The third trial randomly assigned primary care patients to case-finding for depression versus usual care and found no difference between the groups in prevalence of depression at 3-month follow-up. 12 Depressed patients who had been assigned to case-finding were more likely to recover than those who had been assigned to usual care, but after controlling for baseline severity of depression, the mean reduction in symptoms was similar for the case-finding and usual-care groups.
Four observational studies have found no difference in outcomes between depressed patients who were identified by their primary care physicians as depressed and those who were not recognized as depressed. 7,10,11,25 The most recent of these studies reported that patients who were recognized by their primary care physician as depressed had better 3-month outcomes, but no difference in 12-month outcomes, compared with patients who were not recognized as being depressed. 25
Given that effective treatments are available, 26 why does case-finding for depression fail to improve patient outcomes? Even with enhanced detection, the majority of patients identified to have depression do not receive adequate dosage or duration of treatment in primary care settings. 27–35 However, 3 clinical trials that randomly assigned depressed primary care patients to intensive intervention (e.g., increased frequency of visits and surveillance of medication adherence) versus usual care found that patients randomly assigned to the intervention showed significantly greater improvement in depression scores than patients randomly assigned to usual care. 36–38 Perhaps more intensive programs such as the interventions applied in these trials will be needed to improve outcomes of depressed patients in the primary care setting.
An alternative explanation for why case-finding for depression does not affect patient outcomes is that primary care physicians may disregard the clinical significance of their patients' depression scores. We noted that only 12% of our intervention participants attended the educational group sessions. Although patient preferences must be considered, this sparse participation may reflect a lack of encouragement from primary care providers. Successful intervention programs for the treatment of depression will require the education of physicians, hiring of support staff, and streamlining of resources to help patients adhere to recommended therapies for depression. 39
Another reason why providing the results of a case-finding instrument for depression to primary care physicians may not benefit patient outcomes is that many depressed primary care patients may have minimal impairment and improve regardless of treatment. 40,41 Despite the functional morbidity associated with subsyndromal or minor depression, 42–44 in which patients have fewer or less-debilitating symptoms than those required for major depression, only 1 of 4 randomized trials 45 has demonstrated any benefit from therapy for these patients 36,46,47
Although most case-finding instruments for depression have high sensitivity, all of them, including the GDS, are limited by low specificity for detecting depression. 48,49 This means that approximately two thirds of patients who are identified by these instruments as being depressed will not have a clinical diagnosis of depression. Our study and 2 of the 3 previous randomized trials of case-finding for depression used symptom scales rather than a diagnostic interview for depression. 8,9 However, the 1 trial that used an interview diagnosis of depression also found no benefit from case-finding. 12
Our study has several limitations. First, if the intervention were associated with a transient improvement in depression, administering the GDS at 2-year follow-up may have missed this earlier benefit. Second, although we did not find a significant difference in GDS change scores between intervention and control groups (0.3 difference between groups; 95% CI, −0.7 to 1.4), our results are consistent with the possibility of a small benefit from the intervention on the prevalence of depression at follow-up among all participants (8% difference between groups; 95% CI, −6% to 21%). In addition, the change in GDS scores among participants with severe depressive symptoms suggests that this subgroup may have derived some benefit from the intervention. Our study would have needed a much larger sample size to determine whether the intervention was responsible for these results.
Third, we did not exclude patients with a prior diagnosis of depression or bipolar disorder, who may already have received any benefit conferred by early detection and recognition of depression. Fourth, patients who had physical disabilities or did not speak English were excluded from the study; thus, our results may not generalize to this population. Finally, although patient outcomes were determined in a blinded fashion, the participants and physicians in this study could not be blinded to the intervention.
In conclusion, we found that case-finding for depression did not improve outcomes in elderly primary care patients, although we could not exclude the possibility of benefit for a subgroup with severe depressive symptoms. It is unclear whether this lack of effect occurred because of spontaneous improvement in patients with undiagnosed depression, because of patient reluctance to undergo therapy, or because more intensive interventions are necessary to improve patient outcomes. Ongoing studies of improving quality of care for depression may clarify what other interventions must be combined with case-finding to benefit primary care patients with depression.