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

BACKGROUND: Sponsorship bias has never been investigated for non-pharmacological 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 = -0.11 (95% CI -0.21 to -0.02) 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.