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

Background: Transcranial 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.

Methods: We 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.

Results: Dropout 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.

Limitations: Dropout reasons were not systematically reported and adverse events were not collected using questionnaires standardized across studies.

Conclusions: Active tDCS is as acceptable and safe as sham tDCS, as found in randomized clinical trials of MDD.