title: The Influence of Skin Redness on Blinding in Transcranial Direct Current Stimulation Studies: A Crossover Trial.
abstract: OBJECTIVE
  To evaluate whether and to which extent skin redness (erythema) affects investigator blinding in transcranial direct current stimulation (tDCS) trials.
  
  
  METHODS
  Twenty-six volunteers received sham and active tDCS, which was applied with saline-soaked sponges of different thicknesses. High-resolution skin images, taken before and 5, 15, and 30 min after stimulation, were randomized and presented to experienced raters who evaluated erythema intensity and judged on the likelihood of stimulation condition (sham vs. active). In addition, semi-automated image processing generated probability heatmaps and surface area coverage of erythema. Adverse events were also collected.
  
  
  RESULTS
  Erythema was present, but less intense in sham compared to active groups. Erythema intensity was inversely and directly associated to correct sham and active stimulation group allocation, respectively. Our image analyses found that erythema also occurs after sham and its distribution is homogenous below electrodes. Tingling frequency was higher using thin compared to thick sponges, whereas erythema was more intense under thick sponges.
  
  
  CONCLUSIONS
  Optimal investigator blinding is achieved when erythema after tDCS is mild. Erythema distribution under the electrode is patchy, occurs after sham tDCS and varies according to sponge thickness. We discuss methods to address skin erythema-related tDCS unblinding.
authors.affiliation: Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Ezquerro
authors.affiliation: Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.|Service of Interdisciplinary Neuromodulation (SIN), Laboratory of Neurosciences (LIM-27), Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil.
authors.forename: Adriano H
authors.initials: AH
authors.lastname: Moffa
authors.affiliation: Department of Biomedical Engineering, The City College of City University of New York, New York, NY, USA.
authors.forename: Marom
authors.initials: M
authors.lastname: Bikson
authors.affiliation: Department of Biomedical Engineering, The City College of City University of New York, New York, NY, USA.
authors.forename: Niranjan
authors.initials: N
authors.lastname: Khadka
authors.affiliation: Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.|Service of Interdisciplinary Neuromodulation (SIN), Laboratory of Neurosciences (LIM-27), Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil.
authors.forename: Luana V M
authors.initials: LV
authors.lastname: Aparicio
authors.affiliation: Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.|Service of Interdisciplinary Neuromodulation (SIN), Laboratory of Neurosciences (LIM-27), Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil.
authors.forename: Bernardo
authors.initials: B
authors.lastname: de Sampaio-Junior
authors.affiliation: Spaulding Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
authors.affiliation: Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.|Service of Interdisciplinary Neuromodulation (SIN), Laboratory of Neurosciences (LIM-27), Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil.
authors.forename: Isabela M
authors.initials: IM
authors.lastname: Bensenor
authors.affiliation: Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.|Service of Interdisciplinary Neuromodulation (SIN), Laboratory of Neurosciences (LIM-27), Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil.
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Lotufo
authors.affiliation: Heart Institute (INCOR), University of São Paulo, São Paulo, Brazil.
authors.forename: Alexandre Costa
authors.initials: AC
authors.lastname: Pereira
authors.affiliation: Interdisciplinary Center for Applied Neuromodulation (CINA), University Hospital, University of São Paulo, São Paulo, Brazil.|Service of Interdisciplinary Neuromodulation (SIN), Laboratory of Neurosciences (LIM-27), Department and Institute of Psychiatry, University of São Paulo, São Paulo, Brazil.
authors.forename: Andre R
authors.initials: AR
authors.lastname: Brunoni
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004890:Erythema / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D011336:Probability; D012867:Skin / Q000000981:diagnostic imaging; D013997:Time Factors; D065908:Transcranial Direct Current Stimulation / Q000009:adverse effects*; D064232:Visual Analog Scale; D055815:Young Adult
keywords: Adverse effects; blinding; computer modeling; erythema; randomized-controlled trials; skin redness; transcranial direct current stimulation