Correlates of remission in primary care patients treated for minor depression

Abstract

As minor depression is perhaps the most common form of mood disorder seen in primary care, we sought to explore the effects of both pharmacologic and psychosocial interventions for primary care patients with this condition. Three hundred and eighteen primary care patients meeting criteria for minor depression (defined as endorsing 3 or 4 of the nine DSM-IV symptoms of major depression, at least one of which was either depressed mood or anhedonia, for a period of at least four weeks, and scoring ≥10 on the Hamilton Rating Scale for Depression) from 4 diverse geographic sites were enrolled in a randomized controlled 11 week trial of paroxetine, problem-solving therapy or placebo. Patients who attended at least 4 treatment sessions and who received a Hamilton score by an independent rater at either 6 or 11 weeks were used in the analysis (77% of enrolled patients). A score of ≤ 6 on the Hamilton was defined as a positive response to treatment. Fifty four percent of patients met our criteria for remission (HRS-D ≤ 6) by week 11, with no difference among treatments. Patients who were women, younger, of European descent, homemakers or retired persons (as opposed to unemployed) and who had lower baseline severity of depression were more likely to remit across all treatment conditions. Although explicitly addressed in the data analysis, differences in outcomes across the four sites of the investigations limit our confidence in the generalizabilty of our findings. In addition, patients with lower levels of educational attainment had a higher dropout rate, suggesting further caution about the generalizability of the findings. Defining remission in this categorical way, we found no differences among the interventions studied, but did find that outcome was related to demographic and clinical characteristics of the patients. While it is difficult to know why female patients were more likely to remit, this may be a function of the association in our subject populations between male gender and the likelihood (≈ .46) of being a patient in the VA system. The remaining variables associated with higher probability of remission appear to reflect social advantage and lower severity or complexity of illness.

Introduction

Minor depression is one of the most common types of depressive disorders [1], [2]. This is particularly true in medical and primary care populations where the prevalence of depression is 1.5 to 3 times the prevalence in the community [3], [4], [5]. In primary care, rates of minor depression are as much as four times greater than major depression, ranging from 5 to 16% [3], [5], [6], [7], [8]. Differences in the methodology of prevalence studies undoubtedly contribute to some of the variability in reported prevalence rates. Heterogeneity in the concepts of and criteria for minor depression further adds to this variability. There is some evidence that minor depression is a categorically distinct disorder [9], [10], [11]; however, the bulk of the evidence suggests that minor depression is on a continuum with major depression, with the difference being one of severity rather than type [5], [12], [13], [14], [15], [16], [17], [18]. Accordingly, primary care physicians have proposed that the RDC or DSM-IV Appendix criteria for minor depression are most likely to reduce obstacles for identification and treatment of depressive disorders in primary care [19].

The functional consequences of untreated minor depression are substantial. Whether measured cross-sectionally [7], [8], [20], [21] or longitudinally [6], [17], [22] persons with minor depression suffer impairment in function at work, home, and socially. In addition, as many as 10% to 25% develop major depression within the next year [6], [23], [24].

Despite its high prevalence and associated functional impairment, there have been few studies of minor depression that indicate that antidepressants are of benefit to persons with this condition [25], [26], [27], [28]. As with pharmacotherapy, there is still a relative dearth of controlled studies of psychosocial interventions for minor depression [29], despite the preference of many primary care patients for counseling over medications [30]. Because of patient preference [30], [31], primary care physicians take care of at least half of all patients with depression [6], [32], [33]. Thus, if persons are to be treated for depression, it is most likely to occur in the primary care setting.

The Treatment Effectiveness Project (TEP) was designed to examine the relative efficacy of a selective serotonine uptake inhibitor (paroxetine), Problem-Solving Treatment for Primary Care (PST-PC) [34], and placebo plus clinical management in midlife patients (at two sites) and older patients (at four sites) with minor depression and dysthymia enrolled in a large primary care based trial [35], [36]. Specifically, six sessions of a manual-based behavioral treatment (PST-PC) was compared with six sessions of clinical management [37], [38] and either placebo or paroxetine over an 11-week period.

The aim of this report is to present the demographic and clinical correlates of nonresponse to treatment in the patients with minor depression participating in this trial.