The Effect of Cognitive–Behavioral Therapy as an Antidepressive Treatment Is Falling: Reply to Ljòtsson et al. (2017) and Cristea et al. (2017)

Abstract

This article critically reassesses the nonlinear reanalysis by Ljótsson, Hedman, Mattsson, and Andersson (2017) and reviews Cristea et al.’s (2017) extension of our original meta-analysis (Johnsen & Friborg, 2015) reporting a decline in the effects of cognitive–behavioral therapy (CBT) for treating unipolar depression. Ljótsson et al. fitted a piecewise meta-regression model to the data, indicating a halt in the decline from the year 1995 onward, hence concluding that CBT is not gradually losing its efficacy. We reanalyzed the data for nonlinear time trends and replicated their findings for the 34 studies using the Hamilton Rating Scale for Depression as the outcome but not for the 67 studies using Beck’s Depression Inventory as the outcome. The best nonlinear model was quadratic rather than flat (or linear) from 2001 onward, which opposes the conclusion by Ljótsson et al. of stability in effects. Cristea et al. identified additional studies, but their new analyses provided mixed support for a linear decline in CBT effects. They could not dismiss a decline except only in the most stringent analytic condition—namely, when analyzing only 29 randomized controlled trials based on between-groups effect sizes solely. Their study includes several questionable methodological choices, so we expand on the discussion of these disparate meta-analytic findings. Of particular concern is the tendency to downplay the fact that when looking at all of the studies together, there is a clear decline in the effects of CBT, which should concern therapy researchers within the field rather than being explained away.