Fargas‐Babjak 1989.

Methods	Randomised controlled trial 2‐arm parallel group design Trial duration: 13 weeks No power calculation reported
Participants	56 patients randomised 56 patients with knee OA reported at baseline Study joints: 56 joints, most likely > 75% knees Average age; gender, BMI: not reported
Interventions	Experimental intervention: burst TENS, twice per day Control intervention: sham TENS, twice per day Duration of treatment period: 6 weeks Analgesics allowed, but change of dosage prohibited. Unclear whether analgesics were assessed and whether intake was similar between groups. Device: Codetron Self‐administered: yes Waveform: square Pulse width: 1000 µsec Pulse frequency: 200 Hz, train length of 125 ms, repetition frequency of 4 Hz (25 pulses per train) Amplitude: above sensory threshold, highest intensity that could be tolerated without inducing frank pain Duration of stimulation per session: 30 minutes Electrodes: 7 carbon rubber (self‐adhesive) Karaya Pads electrodes of 2 x 3 cm Placement: 10 acupuncture points: GV14, GV4, GB30, GB34, SP13, B1 60, ST36, B1 40, SP9, LI4 and 3 extra tender points
Outcomes	Extracted pain outcome: global pain after 13 weeks described as "Pain improvement (percentage pain improvement based on VAS)" No function outcome reported No primary outcome reported
Notes	*Investigators named their intervention AL‐TENS, but we coded it burst TENS in the analyses
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?	High risk	Quote: "Full details of this (Percent Improvement Pain Scale) are reported elsewhere". Investigators however failed to provide reference.
Adequate blinding of patients?	Low risk	Use of sham device: Codetron, identical in appearance, set at frequency of 0.2 Hz with a threshold electrical stimulus of 0.5 mA, which caused a sensation on the skin but failed causing the deep muscle afferent stimulation
Incomplete outcome reporting: intention‐to‐treat analysis performed? Pain	High risk	56 patients randomised but only 19 analysed in the experimental, and 18 analysed in the control group
Incomplete outcome reporting: intention‐to‐treat analysis performed? Function	Unclear risk	Not applicable
Funding by commercial organisation avoided?	High risk	Sponsor: Electronic Health Machines
Funding by non‐profit organisation?	Low risk	NRC grant no: 689