BACKGROUND: Current knowledge about the long-term outcome of depression is largely based on the results of studies performed with the small selection of patients who are referred to psychiatric professionals. However, because of the high prevalence of depression in the community and in primary care, information about the long-term outcome in these populations is indispensable if physicians are to offer the best possible care in these settings.
METHODS: We performed a literature search to identify relevant papers published between 1970 and 1999 on original long-term follow-up studies of depression in community and primary care populations. The included studies were of adult populations with depression based on diagnostic criteria and a follow-up of at least 5 years. Data about recurrences, relapses, psychopathology, disability, or quality of life at follow-up were examined.
RESULTS: We found 8 studies that fulfilled our criteria. The reported rates of recurrence or depression at follow-up were between 30% and 40%. Higher rates were found in the younger and older age groups. Data about other predictors of outcome, health status, and the relation between treatment and outcome did not justify any hard conclusions.
CONCLUSIONS: The long-term outcome of depression in the community and in primary care is rarely studied. The results of available studies are difficult to compare because of the large differences in populations and methods. Nevertheless, these studies suggest that the long-term prognosis of depression in the community and in primary care is not as poor as in psychiatry.
Depression is regarded as a chronic illness with a high prevalence and a large impact on quality of life.1-6 Nevertheless, the long-term outcome of depression in primary care and in the community is not clear. Most long-term outcome studies of depression have been performed with populations of patients who have been referred to psychiatric specialists.7-11 However, not everyone with depression in the community consults a physician, and usually only the more severe and lasting cases—approximately 5% to 15% of all patients who seek medical attention and have received a diagnosis of depression in primary care—are referred for secondary care.12,13 It is unlikely that the outcome in the community and in primary care is identical to that of referred cases, because of the difference in the prevalence of the various severity levels of depression between these populations.14
The follow-up periods of most studies of depression performed in the community and in primary care have been relatively short.15-17 From these studies we know that patients experience disability during depressive episodes, but we do not have a clear picture of the long-term consequences from the patient perspective.2,4,5 Also, in short-term studies, rates of depression measured at follow-up are not conclusive in determining recurrence rates.
Concerning treatment, it has been established in many short-term studies that antidepressants are effective for the treatment of major depressive disorder11,18,19 and perhaps also for minor depression20-23 (with a high prevalence in community and primary care).24-27
However, papers can be found describing a totally different picture for the long-term outcome of chronic diseases.28,29 These studies demonstrate that short-term effectiveness and safety do not automatically predict long-term outcome. Therefore, we think that knowledge about the long-term course of depression in the community and in primary care, naturalistic as well as treated, is indispensable for determining what treatment strategy is justified. Studies about the negative effects of antidepressants have been published,30-33 and some suggest that these drugs might influence the course of depression in a negative way.34 Long-term outcome information should be available for all levels of depression, including cases for which no medical attention is sought, and differences between naturalistic outcome and outcome after treatment should be clear. We reviewed the literature for long-term outcome studies of depression in the community and in primary care, looking for answers to the following 3 research questions: What is the recurrence rate of depression? Can a relation be found between long-term outcome and treatment? What are the long-term consequences for the health status of the patients involved?
Methods
Retrieval of the Literature
We performed a computerized search of studies from 1970 to 1999 using MEDLINE, Psychlit, Current Contents, and The Cochrane Library. We chose 1970 as our starting point, because at that time modern classification systems were introduced and research diagnostic criteria became available to investigators.
Thesaurus and free text words were combined for “depression/depressive disorder” with “general practice/family practice/primary care” or “community” and “follow-up/course/outcome/prognosis.”
Selection of the Literature
Two reviewers (H.J.S., E.M.vW-B.) made a selection by screening titles and abstracts. If an abstract had been selected by only one of the reviewers it was discussed until consensus was reached.