Care-as-usual control groups across different settings in randomized trials on psychotherapy for adult depression: a meta-analysis

Background: Care-as-usual (CAU) is often used as a control condition in psychotherapy research, but it may vary considerably what that entails, ranging from no treatment, to routine treatment in primary care, general medical care, perinatal care, and specialized mental health care.

Methods: We conducted a meta-analysis of trials comparing psychotherapy for depression to CAU, with a focus on the different categories of CAU and countries where the studies were conducted. We used an existing database of randomized trials on psychotherapy for depression that is updated every year.

Results: A total of 140 studies with 15 419 patients were included. We found no significant differences in effects between categories of CAU (effect sizes ranging from g = 0.43 for CAU in primary care to g = 0.73 for no treatment), but heterogeneity was high in all CAU categories. After stratifying effects across specific countries (within CAU categories) we found that heterogeneity was considerably lower and there were several significant differences between countries. Overall, effects were larger in non-Western countries (g = 0.84 to 1.28) compared to those in Western countries (g = 0.52; p for difference = 0.002). Effects were smaller in studies with risk of bias (p = 0.01).

Conclusions: There are no significant differences between major categories of CAU when compared to psychotherapy conditions in randomized trials. However, effects of psychotherapy differ considerably across CAU conditions in specific countries. CAU therefore is a heterogeneous control condition in psychotherapy research.