Schlager 1998.

Methods	Parallel‐group randomized trial, conducted in Austria. Study dates not reported.
Participants	40 children (3 ‐ 12 years) undergoing strabismus surgery. Excluded: children with gastric or intestinal disease, emesis and vomiting in the previous week, and those who received any medical therapy immediately before surgery. No child withdrew from study.
Interventions	Low‐level laser stimulation performed on each P6 acupoint over 30 seconds, 15 min before induction of anaesthesia and 15 min after arriving in the recovery room (n = 20). Sham laser stimulation held on P6 acupoints but laser beam not activated, 15 min before induction of anaesthesia and 15 min after arriving in the recovery room (n = 20).
Outcomes	Vomiting (0 ‐ 24 h), risk of rescue antiemetic drug.
Notes	Rescue antiemetic was dimenhydrinate suppositories 50 mg. Nurses in the recovery room may not have been blinded to treatment groups. Vomiting (0 ‐ 2 h, 0 ‐ 6 h) also recorded in the paper. Funding source was from Helbo‐Medizintechnik GmbH and the Ludwig Boltzmann Institute for Acupuncture. No details about any declarations of interest among authors.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information.
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. "Neither children nor parents were able to tell if the laser was active".
Blinding of healthcare providers (performance bias) All outcomes	Unclear risk	Insufficient information.
Blinding of outcome assessor (detection bias) All outcomes	Unclear risk	Insufficient information.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data reported for 40 children analysed.
Selective reporting (reporting bias)	Unclear risk	Risk of nausea was not recorded because it may be difficult to assess in children. Authors stated that "stimulation of PC6 with a low‐level laser has no known side effects".
Other bias	Low risk	Baseline characteristics were comparable. "There were no significant differences between the groups in age, sex distribution, ASA status, weight, height, duration of anaesthesia, duration of surgery or number of repaired muscles (table 1)".