Are studies of psychotherapies for depression more or less generalizable than studies of antidepressants?

Background: The generalizability of findings from studies exploring the efficacy of psychotherapy and antidepressants has been called into question in part because studies exclude many patients. Despite this, the frequency with which psychotherapy and antidepressant studies use specific inclusion and exclusion criteria has never been compared. We explored the exclusion criteria used in psychotherapy and pharmacotherapy studies from 1995 to 2014. Method: Systematic literature searches were conducted in PubMed, Medline, PsycINFO, and Embase of published randomized controlled trials (RCTs) of the treatment of major depressive disorder (MDD) in adults with either antidepressants (vs. placebos) or psychotherapy (vs. placebos, treatments as usual, or other controls). Results: Most psychotherapy (81%) and antidepressant (100%) trials excluded patients with milder symptoms as well as patients with elevated suicidal risk (56–75%), psychotic symptoms (84–88%), or substance misuse (75–81%). Psychotherapy studies were less likely to exclude patients on the basis of brief episode duration (0% vs. 48%) and co-morbid Axis I disorders (6% vs. 27%). However, psychotherapy studies excluded patients with more severe symptoms more frequently (38%) than antidepressant studies (8%). Conclusions: Overall, psychotherapy studies appear somewhat more inclusive than antidepressant studies. On average, antidepressant studies appear to target patients with more chronic and severe, as well as more purely depressive presentations.