Harvey 2017

Methods	Parallel RCT
Participants	Country of study: Canada Setting: laboratory Condition: mixed chronic pain (in the over 60s) Prior management details: not reported n = 16 Age, mean (SD): active group 72 (6) years, sham group 71 (8) years Duration of symptoms mean (SD) years: active group 26 (24), sham group 15 (11) Gender distribution: 11 F, 3 M
Interventions	Stimulation type: tDCS Stimulation parameters: tDCS: 2 mA intensity, 20 min Stimulation location: M1 contralateral to painful side Number of treatments: x 1 daily for 5 days Control type: sham tDCS
Outcomes	Primary: pain NRS anchors 0 = no pain 10 = worst imaginable pain When taken: postintervention Secondary: none relevant AEs not reported
Notes	Funding source: G Léonard is supported by the Fonds de Recherche en Santé (FRQ‐S, Montréal, QC, Canada). This project was partially supported by the Neuroscience Centre of Excellence of the Université de Sherbrooke (CeNUS, Sherbrooke, QC, Canada) and an internal start‐up fund from the Research Centre on Aging (Initiatives stratégiques du Centre de recherche sur le vieillissement, Sherbrooke, QC, Canada). COI: study authors report no COI
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Randomization to sham or active tDCS was performed using a random numbers table with a ratio of 1:1, based on order of entry of the participants in the study.”
Allocation concealment (selection bias)	Unclear risk	Comment: allocation concealment not reported
Adequate blinding of participants?	Unclear risk	Comment: blinding can be compromised at 2 mA intensity. No formal blinding assessment reported
Adequate blinding of assessors?	Unclear risk	Comment: blinding can be compromised at 2 mA intensity. No formal blinding assessment reported
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: 2/8 (25%) in active group withdrew. Data appear to have been excluded from analysis
Selective reporting (reporting bias)	Low risk	Comment: outcomes reported adequately
Study Size	High risk	Comment: n = 14
Study duration	High risk	Comment: 1 week postintervention follow‐up
Other bias	High risk	Comment: baseline imbalance in average daily pain