Fregni 2006b

Methods	Parallel RCT; 3 conditions
Participants	Country of study: Brazil Setting: laboratory Condition: fibromyalgia Prior management details: unclear n = 32 Age: 53.4 (SD 8.9) years Duration of symptoms: condition 1: 8.4 (SD 9.3) years; condition 2: 10.0 (SD 7.8) years; condition 3: 8.1 (SD 7.5) years Gender distribution: 32 F
Interventions	Stimulation type: tDCS Stimulation parameters: intensity 2 mA, 35 cm2 electrodes, duration 20 min Stimulation location: condition 1: DLPFC; condition 2: M1; condition 3: sham M1. All conditions contralateral to most painful side or dominant hand Number of treatments: 5, x 1 daily on consecutive days Control type: sham tDCS (switched off after 30 s stimulation)
Outcomes	Primary: pain VAS 0‐10 cm, anchors not specified When taken: at the end of the stimulation period and at 21‐day follow‐up Secondary: QoL: FIQ
Notes	COI: no declaration made Sources of support: support from Harvard Medical School Scholars in Clinical Science programme/ NIH
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was performed using the order of entry into the study and a previous computer‐generated randomisation list, using random blocks of 6 patients (for each 6 patients, 2 were randomised to each group) in order to minimize the risk of unbalanced group sizes."
Allocation concealment (selection bias)	Low risk	Comment: the use of a pre‐generated randomisation list should have adequately ensured this
Adequate blinding of participants?	Unclear risk	Comment: there is evidence that participant blinding of tDCS may be inadequate at 2 mA intensity (see Assessment of risk of bias in included studies)
Adequate blinding of assessors?	Unclear risk	Comment: there is evidence that assessor blinding of tDCS may be inadequate at 2 mA intensity (see Assessment of risk of bias in included studies)
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "One patient (in the M1 group) withdrew, and the few missing data were considered to be missing at random. We analyzed data using the intent‐to‐treat method and the conservative last observation carried forward approach."
Selective reporting (reporting bias)	Unclear risk	Comment: pain score numerical values not provided clearly with measures of variance for most time points in the study report. On request data were available for the primary outcome at 1 follow‐up point but not for other follow‐up points
Study Size	High risk	Comment: < 50 participants per treatment arm
Study duration	Unclear risk	Comment: ≥ 2 weeks but < 8 weeks' follow‐up
Other bias	Low risk	Comment: no significant other bias detected