Strengths and Limitations
Our study has several strengths. It is focused on those depressive disorders, dysthymia and minor depression, that are common in primary care and are treated most often in that setting. The inclusion criteria were broad, permitting results to be generalizable to the majority of patients with these disorders presenting in primary care. The treatments were provided in the primary care setting, emphasizing their potential practicality for primary care practice. For the medication intervention, this placebo-controlled trial contributes to the scientific knowledge base concerning treatments in primary care. There are relatively few such controlled trials for dysthymia and even fewer for minor depression.
This is the first treatment trial outside of the United Kingdom in which the behavioral treatment PST-PC was used. As in the United Kingdom, PST-PC had a high patient acceptance rate; 80% of the patients assigned to it completed all 6 visits and 87% of those coming for one visit completed 4. On some outcome measures, it had effectiveness similar to paroxetine and greater than placebo plus clinical management, although it showed greater variability by site than paroxetine. In this trial, PST-PC therapists varied on the level of previous experience with behavioral therapy treatment, overall experience, and number of patients treated with PST-PC, all variables that may have related to their skill in delivering the treatment. Analyses are in progress to examine the effects of these and other variables on PST-PC outcome. The results reported here indicate PST-PC has promise but cannot be considered an established treatment alternative to antidepressants in depressed primary care patients, as it is in the United Kingdom.
Our study also has shortcomings. The placebo-controlled condition involved contact with a clinician for 6 visits over the 11-week trial, considerably more than usually takes place in primary care. Whether this nonspecific clinician contact related to the relatively high improvement (remission rates) for placebo, particularly for those with minor depression, cannot be assessed in our study. In retrospect, including a true “treatment as usual” group making 2 to 3 in-person visits over 11 weeks would have clarified these results. Also, the clinical significance of the amount of symptom reduction observed in the scale analyses (SF-36-MHC, HSCL-D-20) is difficult to establish. The amounts of those reductions were modest, even when statistically significant. For clinical significance, one must rely primarily on the remission analyses that were based on those patients receiving adequate exposure to the treatments, not an intention-to-treat group.
Further Research
Variation in outcome by site was a problem in this data, as it was in the group of patients 60 years and older. Further analyses have taken place, to be reported in separate publications,34,35 in an attempt to examine the effect of other variables, such as demographics, level of medical comorbidity, or personality variables such as neuroticism. The findings we reported on patients aged 18 to 59 years and those reported elsewhere for the patients 60 years and older are examining only the effects of diagnosis, treatment received, and site. The effect, if any, of various moderator variables was not examined but will be in these later reports.
Conclusions
Evidence-based guidelines are available to direct primary care physicians’ treatment for major depression, and when implemented well, they improve patient outcomes.27,36,37 For the treatment of minor depression and dysthymia, evidence-based guidelines are unavailable, because the evidence base is insufficient to develop recommendations.
Our results showed that paroxetine andto a lesser degree PST-PC improved remission of dysthymia more than the use of placebo plus nonspecific clinical management. Results varied for the other outcomes measured. For minor depression, the 3 interventions (paroxetine, PST-PC, and placebo) were equally effective, so general clinical management is an appropriate treatment option.
Acknowledgments
Our project was supported by the John D. and Catherine T. MacArthur Foundation, Chicago, Illinois, and by the John A. Hartford Foundation, New York, New York. In the early planning stages of the project design advice was provided by George Alexopoulis, MD; Daniel Blazer, MD; Christopher Callahan, MD; Charles Reynolds, MD; Carl Salzman, PhD; and Herbert Schulberg, PhD. Helena Kraemer, PhD, from Stanford University provided statistical and data analytic advice; Laurence Mynors-Wallis, MD, currently at the University of Southampton provided the initial training in PST-PC.
Related resources
- Agency for Health Care Policy and Research—Consumer Guideline #5: Depression is a Treatable llness http://text.nlm.nih.gov/ftrs/pick?collect=ahcpr&dbName=depp&cd=1&t=96928766
- American Medical Association—Consumer Health Information: Insight on Depression http://www.ama-assn.org/insight/spec_con/depressn/depressn.htm
- American Psychiatric Association—APA On-line Public Information http://www.psych.org/public_info
- American Psychological Association—APA Resources for the Public: What You Need to Know About Depression http://www.apa.org/psychnet/depression.html
- MacArthur Initiative on Depression in Primary care www.depression-primarycare.org