title: Comparison of blinding effectiveness between sham tDCS and placebo sertraline in a 6-week major depression randomized clinical trial.
abstract: OBJECTIVE
  To compare blinding integrity and associated factors for transcranial direct current stimulation (tDCS) vs. placebo-pill, the gold standard blinding method.
  
  
  METHODS
  Parallel trial. Depressed participants were randomized to verum/placebo sertraline and active/sham tDCS (2mA, 30-min 10-daily sessions and two additional, fortnight sessions) over 6weeks. Blinding was assessed in completers (n=102) and in a random subgroup (n=35) of raters and participants, in which we also inquired to qualitatively describe their strongest guessing reason.
  
  
  RESULTS
  Participants and raters presented similar performance for predicting treatment assignment at endpoint, correctly guessing tDCS and sertraline beyond chance. Nevertheless, clinical response was associated with correct prediction and tDCS non-responders failed to predict the allocation group. For tDCS, "trouble concentrating" was inversely associated with correct prediction. "Skin redness" was more reported for active-tDCS, but did not predict the allocation group. The qualitative reasons for raters' guessing were not associated with correct prediction, whereas for participants clinical response and adverse effects were directly and inversely associated with correct prediction, respectively.
  
  
  CONCLUSIONS
  Blinding integrity of tDCS and sertraline were comparable and mainly associated with efficacy rather than blinding failure.
  
  
  CONCLUSIONS
  TDCS blinding can be improved by adopting parallel designs and avoiding subjects' awareness of skin redness.
authors.affiliation: Center for Clinical and Epidemiological Research, University Hospital, Faculty of Medicine, University of São Paulo, São Paulo, Brazil; Interdisciplinary Center for Applied Neuromodulation, University Hospital, University of São Paulo, São Paulo, Brazil. Electronic address: brunoni@usp.br.
authors.forename: André Russowsky
authors.initials: AR
authors.lastname: Brunoni
authors.affiliation: Department of Internal Medicine, UFRGS, Brazil; Neurology Service, EMG Unit, Hospital de Clínicas de Porto Alegre, Brazil.
authors.forename: Pedro
authors.initials: P
authors.lastname: Schestatsky
authors.affiliation: Center for Clinical and Epidemiological Research, University Hospital, Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Paulo Andrade
authors.initials: PA
authors.lastname: Lotufo
authors.affiliation: Center for Clinical and Epidemiological Research, University Hospital, Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Isabela Martins
authors.initials: IM
authors.lastname: Benseñor
authors.affiliation: Laboratory of Neuromodulation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D003865:Major Depressive Disorder / Q000188:drug therapy / Q000628:therapy*; D004311:Double-Blind Method; D004599:Electric Stimulation Therapy / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012107:Research Design; D020280:Sertraline / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000928:Antidepressive Agents; D020280:Sertraline
keywords: Clinical trial; Double-blind methods; Major depressive disorder; Placebo; Transcranial direct current stimulation