Conceptual and methodological issues in comparative studies of psychotherapy and pharmacotherapy, II: Nature and timing of treatment effects.

This is the second of two articles on the conceptual and methodological problems involved in comparing the effectiveness of drugs and psychotherapy in the treatment of mental disorders. Part II focuses on differences between psychotherapy and pharmacotherapy in the nature of treatment effects and related goals for treatment, differences in the time course of treatment effects, and potential sources of bias in the research setting. In designing comparative studies of psychotherapy and pharmacotherapy, investigators should address methodological choices explicitly and consider the implications for interpretation of findings.