The principal finding of this analysis is that the PROSPECT intervention was more effective than usual care in promoting remission of depression in elderly primary care patients, especially when remission was defined as a Hamilton depression scale score lower than 10. Differences in remission rates between intervention and usual care were most pronounced among depressed elders experiencing hopelessness. When remission was defined according to stricter criteria, i.e., Hamilton depression scale score less than 7, the intervention group had numerically higher rates of remission during the early phases of treatment but, when the whole 18-month period was taken into consideration, differences in remission rates did not reach significance. Regardless of the remission criterion, depressed patients with comorbid anxiety disorders, hopelessness, and limitations in physical and emotional functioning were associated with low remission rates in primary care elderly patients receiving either the intervention or usual care.
A strength of this study is the use of random sampling and screening that may have resulted in a representative sample of depressed older primary care patients. Therefore, its findings may be relevant to clinical practice. Limitations of the study include the lack of blinding of raters, the infrequent follow-up, the lack of information on discrete medical problems of participants, and the lack of information about specific antidepressant treatments received by each group during the 18 months of the study. While more frequent follow-up assessments would have been desirable, concerns about participant burden and cost led us to select few, yet clinically meaningful, follow-up times. This analysis used disability resulting from physical problems as a proxy of medical burden (the Short-Form Health Survey physical component summary). Data on specific medical disorders and their impact on remission need further attention. Finally, treatment changed frequently both in the intervention and the usual care practices. Future analyses may compare the impact on remission of selected treatments at specific times. Nonetheless, focusing on predictors of the first remission occurrence serves to identify the clinical profile of elderly primary care patients likely to remain depressed and in need of close follow-up and perhaps referral to mental health specialists.
The favorable remission rates of the PROSPECT intervention on depression is consistent with evidence that interventions aimed at changing primary care practice can improve the quality of depression care in mixed-age (14
) and elderly (15
) patients. Despite differences in design, measurements, and type of intervention, both the PROSPECT and the Improving Mood-Promoting Access to Collaborative Treatment studies (the latter being another study of depressed primary care elders) demonstrated differences in remission rates favoring the intervention over usual care (15
). These findings underscore the value of such interventions for resolving late-life depression in primary care patients.
Remission occurred earlier for patients in practices providing the intervention than for those in practices providing usual care. By 8 months, 43% of patients receiving the care management intervention had achieved remission (Hamilton depression scale score <10) compared with 28% of patients receiving usual care. The remission rate with usual care eventually reached the level achieved with the intervention, perhaps reflecting the fact that some depressive episodes eventually subside and those that persist or worsen receive additional attention. These observations suggest that in at least some patients, the use of trained care managers can accelerate remission and perhaps reduce suffering, disability, and family disruption several months earlier than usual care.
Compromised physical and emotional function predicted low remission rates in patients treated by either the intervention or usual care. There is evidence, however, that antidepressant treatment and reduction of depressive symptoms can improve the functional status of elderly patients (35
). These observations suggest that older primary care patients with major depression and physical and emotional function limitations need aggressive antidepressant treatment and perhaps referral to mental health professionals if their symptoms persist.
Depressed elderly primary care patients experiencing hopelessness were more likely to benefit from the PROSPECT intervention than usual care. Hopelessness is a set of beliefs that influence how a person interprets information and behaves. Hopeless thoughts can be chronic and persistent in some individuals and activated during depression in others (36
). Hopelessness has a strong association with suicidal ideation and behavior in younger adults (37
). A similar relationship between hopelessness and suicidal ideation was demonstrated in institutionalized elderly patients and was dependent upon the level of depression (38
). Hopelessness was associated with suicidal ideation in patients with severe depression, but there was no significant relationship between hopelessness and suicidal ideation in patients with mild depression. These observations suggest that elderly primary care patients experiencing hopelessness require special clinical attention—and perhaps a referral to care managers—since these patients have a low likelihood for remission under usual care and may even be at increased risk for suicide, especially in the presence of a severe depression. The provision of care management is particularly feasible in large medical practices such as HMOs, which often include behavioral specialists on their staff.
Anxiety adversely influenced the rate of remission in patients of the intervention practices, whereas it had a non-significant effect in patients receiving usual care. Specifically, the intervention was more effective than usual care in patients with low anxiety but added little benefit for patients with higher anxiety severity. Patients with comorbid anxiety and depression frequently exhibit more severe symptoms overall, have a more protracted course of illness, and experience less positive treatment outcomes (39
). Therefore, care management may be insufficient treatment for some anxious depressed elderly primary care patients, and their physicians should recognize this clinical pattern as one of several warranting referral to a psychiatrist.
Primary care occupies a strategic position in the management of late-life depression. This study has documented that remission of late-life depression occurs in a large percentage of primary care patients. Collaborative care by trained care managers and primary care physicians leads to earlier remission than usual care and can reduce suffering and disability. As many of the care managers’ services are reimbursable under the existing Medicare codes, referral to appropriately trained care managers is feasible. Priority for such services may be given to depressed elders experiencing hopelessness, since usual care is less likely to be helpful. Longitudinal assessment of anxiety and limitations in physical and emotional functioning of depressed older primary care patients is critical. Some patients with prominent impairment in these areas may not achieve remission when treated in primary care settings and may require mental health consultation and care.