What Constitutes Sufficient Evidence for Case Formulation–Driven CBT for Psychosis? Cumulative Meta-analysis of the Effect on Hallucinations and Delusions

Abstract

Abstract Objective Following 2 decades of research on cognitive behavioral therapy for psychosis (CBTp), it is relevant to consider at which point the evidence base is considered sufficient. We completed a cumulative meta-analysis to assess the sufficiency and stability of the evidence base for hallucinations and delusions. Method We updated the systematic search from our previous meta-analytic review from August 2013 until December 2019. We identified 20 new randomized controlled trials (RCTs) resulting in inclusion of 35 RCTs comparing CBTp with treatment-as-usual (TAU) or active controls (AC). We analyzed data from participants with psychosis (N = 2407) over 75 conventional meta-analytic comparisons. We completed cumulative meta-analyses (including fail-safe ratios) for key comparisons. Publication bias, heterogeneity, and risk of bias were examined. Results Cumulative meta-analyses demonstrated sufficiency and stability of evidence for hallucinations and delusions. The fail-safe ratio demonstrated that the evidence base was sufficient in 2016 for hallucinations and 2015 for delusions. In conventional meta-analyses, CBTp was superior for hallucinations (g = 0.34, P < .01) and delusions (g = 0.37, P < .01) when compared with any control. Compared with TAU, CBTp demonstrated superiority for hallucinations (g = 0.34, P < .01) and delusions (g = 0.37, P < .01). Compared with AC, CBT was superior for hallucinations (g = 0.34, P < .01), but not for delusions although this comparison was underpowered. Sensitivity analyses for case formulation, primary outcome focus, and risk of bias demonstrated increases in effect magnitude for hallucinations. Conclusions The evidence base for the effect of CBTp on hallucinations and delusions demonstrates sufficiency and stability across comparisons, suggesting limited value of new trials evaluating generic CBTp.