Psychotherapy in Antidepressant Patients

December 2002 (Revised from October 2002). Depression is a condition with various modes of treatment, including pharmacotherapy, psychotherapy, and some combination of each. The role of psychotherapy in the treatment of depression relative to the role of pharmacotherapy is not well understood, and guidelines for psychotherapy in the primary care setting differ from guidelines for specialty care. There is little evidence about the circumstances in actual practice that affect the use of psychotherapy in conjunction with pharmacotherapy. We retrospectively identify the most important factors associated with the use of psychotherapy in combination with pharmacotherapy in the treatment of depression. Specifically, we study provider choice, health plan characteristics, and patient characteristics. We use a comprehensive medical and pharmacy claims data sample of 1,023 individuals during 1992–1994. We select persons prescribed with an antidepressant medication and diagnosed with a depressive disorder by a primary care physician, psychiatrist, or non-physician mental health specialist. Controlling for depression diagnosis and severity, comorbidity, and demographics, we examine the role of provider type and plan benefit characteristics. We study the intensity of psychotherapy using zero-inflated count regression, the intensity of pharmacotherapy using truncated count regression, and the likelihood of relapse of depression using logistic regression. Patients initially seeing a psychiatrist receive more than double the amount of psychotherapy and slightly more pharmacotherapy than patients of other providers. An additional prescription for antidepressant medication reduces by five percent the likelihood of relapse into depression, but the amount of psychotherapy does not affect relapse. Patients seeing a psychiatrist are half as likely to relapse, independent of any effect of psychotherapy. Case management and coinsurance rates do not affect the amount of psychotherapy, but the presence of case management has a positive effect on the amount of pharmacotherapy and on the likelihood of relapse. We find no discernible pattern of complementarity or substitution between pharmacotherapy and psychotherapy across providers. Although the amount of psychotherapy provided in conjunction with medication does not affect the rate of relapse to depression, psychotherapy may nonetheless provide beneficial outcomes not studied here. Choice of a psychiatrist reduces the likelihood of relapse, independent of the number of psychotherapy sessions and antidepressant prescriptions. The effect of provider choice on relapse could be an artifact of differences in provider follow-up practices or could represent a difference in provider skills. Managed care strategies do not appear to reduce the intensity of depression treatment, but case management does increase the likelihood of relapse. Pharmacotherapy and psychotherapy appear to be neither substitutes nor complements in the treatment of depression, suggesting that treatment is individualized. Choice of psychiatrist as the initial provider appears to reduce the likelihood of relapse, suggesting models of coordinated care may be beneficial. The link between psychiatrists and more psychotherapy is consistent with the hypothesis that patients resistant to treatment may nonetheless receive high quality care. Managed care tools such as case management and coinsurance rates do not appear to restrict the use of either psychotherapy or pharmacotherapy. The association of case management with an increased likelihood of relapse suggests that plan characteristics can affect outcomes. Our study focuses on psychotherapy combined with medication and does not psychotherapy alone in the treatment of depression, which may be a preferred mode of treatment for some. Outcomes other than relapse, as well as costs, should also be considered. Our findings that psychiatrists are associated with a decreased likelihood of relapse and that case management is associated with an increased likelihood of relapse despite a correlation with greater pharmacotherapy intensity present avenues for additional study. Key Words: depression, psychotherapy, pharmacotherapy, relapse, count models, zero inflated negative binomial regression