Safety and acceptability of transcranial direct current stimulation for the acute treatment of major depressive episodes: Analysis of individual patient data

•Active tDCS is as acceptable and safe as sham in randomized clinical trials of MDD.•Higher tDCS doses did not affect the overall acceptability.•TDCS dropout rates were less than one third of selective serotonin reuptake inhibitor (SSRIs) and tricyclic antidepressants (TCAs) in treating depression.

BackgroundTranscranial direct current stimulation (tDCS) is a non-invasive brain stimulation modality that has been increasingly used for major depressive disorder (MDD) treatment. Although studies in healthy volunteers showed that the technique is well-tolerated, tDCS safety and acceptability have not been sufficiently explored in patients with MDD.MethodsWe collected individual patient data from 6 randomized clinical trials that had been previously identified in a systematic review and meta-analysis. Primary outcomes were safety (rate of adverse events) and acceptability (rate of dropouts). Secondary outcomes were clinical, demographic and treatment predictors of the primary outcomes.ResultsDropout rates between active (8.8%) and sham (12%) groups were not significantly different (OR= 0.7, p=0.38). Adverse event rates between active (73.5%) and sham (68.3%) groups were not significantly different (OR= 1.4, p= 0.23). Higher current densities were associated with lower adverse event rates.LimitationsDropout reasons were not systematically reported and adverse events were not collected using questionnaires standardized across studies.ConclusionsActive tDCS is as acceptable and safe as sham tDCS, as found in randomized clinical trials of MDD.