Tan 2000

Methods	Cross‐over RCT
Participants	Country of study: USA Setting: tertiary care teaching hospital Condition: neuromuscular pain (excluding fibromyalgia) Prior management details: unclear n = 28 Age: 45‐65 years, mean 55.6 Duration of symptoms: 4‐45 years, mean 15 Gender distribution: 25 M, 3 F
Interventions	Stimulation type: CES Stimulation parameters: frequency 0.5 Hz; pulse width not specified; intensity 10‐600 μA; waveform shape not specified Stimulation location: ear clip electrodes Number of treatments: 12, frequency of treatment not specified Control type: sham CES unit indistinguishable from active unit
Outcomes	Primary: VAS 0‐5 pain intensity When taken: pre‐ and post‐ each treatment Secondary: life interference scale, sickness impact profile ‐ Roland Scale When taken: not specified
Notes	AEs: not reported 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: "each subject was randomly assigned to receive either the active or the sham treatment first" Comment: method of randomisation not specified but less critical in cross‐over design
Adequate blinding of participants?	Low risk	Quote: "sham treatment was made possible by having the treatment delivered via a black box" Comment: sham and active stimulators visually indistinguishable
Adequate blinding of assessors?	Unclear risk	Comment: blinding of assessors not reported
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: only 17 participants completed the study and this dropout (over 50%) is not clearly accounted for in the analysis
Selective reporting (reporting bias)	Low risk	Comment: primary outcome data presented clearly
Free from carry‐over effects?	Low risk	Quote: "Note that there were no significant differences in pain ratings pre‐post changes between the active and sham groups"
Study Size	High risk	Comment: < 50 participants per treatment arm
Study duration	High risk	Comment: < 2 weeks' follow‐up
Other bias	Unclear risk	Comment: participants also received local stimulation to the painful area that may have elicited a therapeutic effect