Valle 2009

Methods	Parallel RCT, 3 conditions
Participants	Country of study: Brazil Setting: laboratory Condition: fibromyalgia Prior management details: refractory to medical intervention n = 41 Age: mean 54.8 (SD 9.6) years Duration of symptoms: condition 1: 7.54 (SD 3.93) years; condition 2: 8.39 (SD 2.06) years; condition 3: 8.69 (SD 3.61) years Gender distribution: 0 M, 41 F
Interventions	Stimulation type: tDCS Stimulation parameters: intensity 2 mA, 35 cm2 electrodes, duration 20 min Stimulation location: condition 1: L DLPFC; condition 2: L M1, condition 3; sham L M1 Number of treatments: 10, x 1 daily on consecutive working days Control type: sham tDCS (switched off after 30 s stimulation)
Outcomes	Primary: pain VAS 0‐10 cm, anchors not specified When taken: immediately post‐treatment, averaged over 3 d post‐treatment, 30 and 60 d post‐treatment Secondary: QoL; FIQ
Notes	COI: no declaration made Sources of support: no declaration made
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was performed using the order of entrance in the study and a previous randomisation list generated by a computer"
Allocation concealment (selection bias)	Low risk	Comment: the use of a pregenerated 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	Comment: no dropout occurred
Selective reporting (reporting bias)	High risk	Comment: pain score numerical values not provided clearly with measures of variance for any post‐treatment time point in the study report
Study Size	High risk	Comment: < 50 participants per treatment arm
Study duration	Low risk	Comment: ≥ 8 weeks' follow‐up
Other bias	Low risk	Comment: no significant other bias detected