Itoh 2008.

Methods	Randomised controlled trial 2 x 2 factorial design Trial duration: 10 weeks No power calculation reported
Participants	32 patients randomised 32 patients with knee OA reported at baseline Study joints: 32 knees Number of females: 21 of 32 (66%)
Interventions	Experimental intervention: interferential current stimulation*, once per week Control intervention: no intervention, optional use of poultice 16 out of 32 patients (50%) allocated to acupuncture using a factorial design; no evidence for an interaction between treatments Duration of treatment period: 5 weeks Analgesics allowed and intake assessed, but unclear whether intake was similar. Device: HV‐F3000 (single channel, 2 pole) Self‐administered: no Waveform: sinusoidal Pulse width: not applicable Pulse frequency: amplitude‐modulated frequency of 122 Hz (beat frequency) Amplitude: above sensory threshold, up to a tingling sensation, 2 to 3 times above sensory threshold Duration of stimulation per session: 15 minutes Placement: site of tenderness and opposite site Electrodes: 2 disposable electrodes different in size, 809 mm2 and 5688 mm2
Outcomes	Extracted pain outcome: global pain after 10 weeks, described as "Pain intensity (VAS)" Extracted function outcome: WOMAC global scale after 10 weeks (VAS) Primary outcomes: pain intensity, WOMAC global scale
Notes	*The investigators used the label TENS in their report, but from their description of the intervention it was clear that interferential current stimulation was applied
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Computer generated block randomisation. Quote "According to a block randomised allocation table (generated by Sample Size, version 2.0, Int), the enrolled patients were allocated to (1) the control (CT) group, (2) the acupuncture (ACP) group, (3) the transcutaneous electrical nerve stimulation (TENS) group or (4) the acupuncture and TENS (A&T) group."
Allocation concealment?	Unclear risk	No information provided
Free of selective reporting?	Unclear risk	Insufficient information provided, no access to study protocol
Adequate blinding of patients?	High risk	No sham intervention
Incomplete outcome reporting: intention‐to‐treat analysis performed? Pain	High risk	12 out of 16 (75%) randomised to experimental and 12 out of 16 (75%) randomised to control group were analysed
Incomplete outcome reporting: intention‐to‐treat analysis performed? Function	High risk	See above
Funding by commercial organisation avoided?	Unclear risk	No information provided
Funding by non‐profit organisation?	Unclear risk	No information provided