Rintala 2010

Methods	Parallel RCT
Participants	Country of study: USA Setting: outpatient clinic, participants took device home Condition: pain related to Parkinson's disease Prior management details: not reported n = 19 (reduced to 13 through dropout) Age mean (SD): active group 74.7 (7.8) years, sham group 74.4 (8.3) years Duration of symptoms: > 6 months Gender distribution: 15 M, 4 F
Interventions	Stimulation type: CES Stimulation parameters: frequency not specified; pulse width not specified; intensity 100 μA; waveform shape not specified; duration 40 min per session Stimulation location: earlobe clips Number of treatments: 42, x 1 daily for 42 days Control type: sham CES unit indistinguishable from active unit
Outcomes	Primary: pain VAS 0 ‐10, anchors not reported When taken: at the end of the treatment period Secondary: none
Notes	Sources of support: equipment provided by CES manufacturer as an "unrestricted gift" COI: no declaration made
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: stated randomised but method of randomisation not reported
Allocation concealment (selection bias)	Unclear risk	Comment: allocation concealment not reported
Adequate blinding of participants?	Low risk	Comment: see above comment
Adequate blinding of assessors?	Low risk	Comment: participants and the study co‐ordinator were blinded to group assignment and the code sheet indicating which devices were active and which were sham was kept by another person who was not in contact with the participants
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: > 30% dropout
Selective reporting (reporting bias)	Low risk	Comment: mean (SD) pain scores reported for both groups pre‐ and poststimulation
Study Size	High risk	Comment: < 50 participants per treatment arm
Study duration	High risk	Comment: < 2 weeks' follow‐up
Other bias	Low risk	Comment: no other bias detected