Cheing 2002.

Methods	Randomised controlled trial 4‐arm parallel group design Trial duration: 8 weeks Randomisation stratified according to age, gender, BMI No power calculation reported
Participants	66 patients randomised 62 patients with knee OA reported at baseline Study joints: 62 knees Number of females: 53 of 62 (85%) Average age: 64 years Average BMI: 28 kg/m2
Interventions	Comparison 1 Experimental intervention: 60 min TENS, 5 times per week Control intervention: sham TENS, 5 times per week Comparison 2 Experimental intervention: TENS plus exercise, 5 times per week Control intervention: exercise alone, 5 times per week Duration of treatment period: 4 weeks Analgesics allowed, unclear whether intake was similar between groups Device: MAXIMA III (dual channel) Self‐administered: unclear, most likely not Waveform: square Pulse width: 140 µsec Pulse frequency: 80 Hz Amplitude: above sensory threshold, tingling sensation, 3 to 4 times above sensory threshold Duration of stimulation per session: 60 minutes Electrodes: 4 electrodes of 4 x 4 cm Placement: at acupuncture points: ST35, SP9, GB34, extra 31,32 (one electrode covering both extra 32 and ST35)
Outcomes	Extracted pain outcome: global pain after 8 weeks, described as "Intensity of subjective pain sensation (Baseline score on 0‐10 cm VAS was standardised to be 100% in each of the groups. Follow up values were expressed as mean decrease in % from baseline)". No function outcome reported No primary outcome reported
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	No information provided
Allocation concealment?	Unclear risk	No information provided
Free of selective reporting?	Unclear risk	Trial protocol not accessible, methods section not explicit about pre‐specified outcomes
Adequate blinding of patients?	Low risk	Comparison 1: Yes, sham device identical in appearance to real TENS unit, no current passed but indicator light was lit up Comparison 2: No, no sham intervention
Incomplete outcome reporting: intention‐to‐treat analysis performed? Pain	High risk	Comparison 1: 16 out of 16 (100%) randomised to experimental and 16 out of 18 (89%) randomised to control group were analysed Comparison 2: 15 out of 17 (88%) randomised to experimental and 15 out of 15 (100%) randomised to control group were analysed
Incomplete outcome reporting: intention‐to‐treat analysis performed? Function	Unclear risk	Not applicable
Funding by commercial organisation avoided?	Unclear risk	No information provided
Funding by non‐profit organisation?	Unclear risk	No information provided