Rusy 2002.

Methods	Parallel‐group randomized trial, conducted in United States. Study dates not reported.
Participants	121 children (4 ‐ 18 years) undergoing tonsillectomy with or without adenoidectomy. Exclusions: presence of skin lesions near acupuncture sites, previous and severe PONV, chronic history of nausea and vomiting. 1 child disqualified after enrolment when propofol was administered during the anaesthetic.
Interventions	1. Electro‐acupuncture at P6 for 20 min after child was awake (n = 40). 2. Sham electro‐acupuncture at P2 for 20 min after child was awake (n = 40). 3. Sham reference group had no needles inserted. Insulated wires were attached to insides of arm and stimulation box was activated to maintain blinding (n = 40).
Outcomes	Vomiting (0 ‐ 24 h), nausea (0 ‐ 24 h), risk of rescue antiemetic drugs.
Notes	Rescue antiemetics were ondansetron and droperidol IV. Sham electro‐acupuncture and sham reference group data were combined for analysis. Funding source was the Jane B Pettit Pain Foundation, Children's Hospital of Wisconsin. No details about any declarations of interest among authors.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"A randomized block design procedure was used to assign enrollees to one of three groups..".
Allocation concealment (selection bias)	Unclear risk	Insufficient information.
Blinding of patients (performance bias) All outcomes	Low risk	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers (performance bias) All outcomes	Low risk	"Experienced recovery room nurses, who were blinded to the treatment group, assessed nausea and vomiting".
Blinding of outcome assessor (detection bias) All outcomes	Low risk	"Experienced recovery room nurses, who were blinded to the treatment group, assessed nausea and vomiting".
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reason for withdrawal of one participants was given. No missing data reported for 120 participants analysed.
Selective reporting (reporting bias)	Unclear risk	There was no description about side effects of therapy in the trial, but in the correspondence (Rusy 2002) the authors wrote "There were no noted muscle contractions or patients who complained of paresthesias during the study".
Other bias	Low risk	Baseline characteristics were comparable. "The groups were similar for age, sex, weight, analgesics administered, and surgical time (table 1), with no differences found".