Efficacy and acceptability of transcranial direct current stimulation (tDCS) for major depressive disorder: An individual patient data meta-analysis.

We evaluated the efficacy and acceptability of transcranial direct current stimulation (tDCS) for treating acute depressive episodes using individual patient data that provide more precise estimates than aggregate data meta-analysis. A systematic review of placebo-controlled trials on tDCS as only intervention was conducted until December-2018. Data from each study was collated to estimate odds ratio (OR) and number needed to treat (NNT) of response and remission, and depression improvement. Endpoints were pre-determined. Nine eligible studies (572 participants), presenting moderate/high certainty of evidence, were included. Active tDCS was significantly superior to sham for response (30.9% vs. 18.9% respectively; OR = 1.96, 95%CI [1.30-2.95], NNT = 9), remission (19.9% vs. 11.7%, OR = 1.94 [1.19-3.16], NNT = 13) and depression improvement (effect size of β = 0.31, [0.15-0.47]). Moreover, continuous clinical improvement was observed even after the end of acute tDCS treatment. There were no differences in all-cause discontinuation rates and no predictors of response were identified. To conclude, active tDCS was statistically superior to sham in all outcomes, although its clinical effects were moderate.