Sponsorship bias in the comparative efficacy of psychotherapy and pharmacotherapy for adult depression: meta-analysis

Background Sponsorship bias has never been investigated for nonpharmacological treatments like psychotherapy. Aims We examined industry funding and author financial conflict of interest (COI) in randomised controlled trials directly comparing psychotherapy and pharmacotherapy in depression. Method We conducted a meta-analysis with subgroup comparisons for industry v. non-industry-funded trials, and respectively for trial reports with author financial COI v. those without. Results In total, 45 studies were included. In most analyses, pharmacotherapy consistently showed significant effectiveness over psychotherapy, g =70.11 (95% CI 70.21 to 70.02) in industry-funded trials. Differences between industry and non-industry-funded trials were significant, a result only partly confirmed in sensitivity analyses. We identified five instances where authors of the original article had not reported financial COI. Conclusions Industry-funded trials for depression appear to subtly favour pharmacotherapy over psychotherapy. Disclosure of all financial ties with the pharmaceutical industry should be encouraged.