Sertraline and/or interpersonal psychotherapy for patients with dysthymic disorder in primary care: 6-month comparison with longitudinal 2-year follow-up of effectiveness and costs
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BACKGROUND: There is little information on the long-term effects and costs of a combination of Sertraline and interpersonal psychotherapy (IPT) for the treatment of dysthymia in primary care. METHODS: In a single-blind, randomized clinical trial, 707 adults (18-74 years of age inclusive) with DSM-IV dysthymic disorder, with or without past and/or current major depression, as an acute or chronic episode, in a community-based primary care practice in Ontario, Canada, were randomized to treatment with either Sertraline alone (50-200 mg), or IPT alone (10 sessions), or Sertraline plus IPT combined. In the acute treatment phase (first 6 months) all groups received full active treatment. This was followed by an additional 18-month naturalistic follow-up phase. Subjects were assessed for effectiveness of treatment in reducing depressive symptoms using the Montgomery Asberg Depression Rating Scale (MADRS) at 6 months and twice again during the 18-month follow-up by blind independent observers. Treatment costs and subjects' use of other health and social services were also investigated. RESULTS: At 6 months, 586 subjects completed the MADRS questionnaire. There was a significant difference (P=0.025) in mean MADRS scores: 14.3 (Group I); 14.9 (Group II); 16.8 (Group III), using analysis of covariance. Response (40% improvement) rates were 60.2% for Sertraline alone, 46.6% for IPT alone, and 57.5% for Sertraline augmented by IPT (P=0.02). At 2 years, 525 subjects were retained for follow-up. There was no statistically significant difference between Sertraline alone and Sertraline plus IPT in symptom reduction. However, both were more effective than IPT alone in reducing depressive symptoms (P=0.03). There was a statistically significant difference between groups in costs for use of health and social services. The IPT treatment groups had the lower costs for use of health and social services. CONCLUSIONS: Sertraline or Sertraline plus IPT was more effective than IPT alone after 6 months. Over the long term (2 years), all three treatments provide reasonably effective treatment for reducing symptoms of dysthymia, but Sertraline or combining Sertraline with IPT is more effective than IPT alone. Of these two more effective treatments, subjects in the Sertraline plus IPT group had less health and social service costs by $480 per person over 2 years. These findings underscore the effects of combining pharmacotherapy and psychotherapy and the economic value of this more comprehensive treatment of dysthymia in primary care.