Koo 2013.

Methods	Parallel‐group randomized trial that compared capsicum plaster stimulation of P6, K‐D2 and sham acupoints. Study conducted in Korea.
Participants	184 adults, aged 21 ‐ 64 years, undergoing thyroid surgery between November 2012 and March 2013. Exclusion: obese, gastro‐oesophageal reflux, use of antiemetic, histamine H₂‐receptor antagonist or tranquillizer within 72 hours before surgery, or respiratory disease.
Interventions	Group 1: Sham P6 and K‐D2 inactive tape, similar in appearance to capsicum plaster, applied to both wrists at P6 acupoint and both deltoid 30 min before induction of anaesthesia and left on for 8 h (n = 46). Group 2: Capsicum plaster applied to both wrists at P6 acupoints and inactive tape applied at both deltoids 30 min before induction of anaesthesia and left on for 8 h (n = 46). Group 3: Capsium plaster applied to both K‐D2 points on index finger of hand and inactive tape applied at both deltoids 30 min before induction of anaesthesia and left on for 8 h (n = 46). Group 4: Capsium plaster applied to both deltoids and inactive tape applied to both wrists at P6 acupoint 30 min before induction of anaesthesia and left on for 8 h (n = 46).
Outcomes	Nausea (0 ‐ 24 h), vomiting (0 ‐ 24 h), rescue antiemetic (metoclopramide 10 mg IV).
Notes	Groups 3 and 4 were not included in the analysis. Power calculation done. No details about financial support or conflict of interests of authors reported in article.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information.
Allocation concealment (selection bias)	Unclear risk	"After enrolment, patients were randomized to four groups by sealed envelope." Comment: no details about use of sequential numbering or opaque envelopes.
Blinding of patients (performance bias) All outcomes	Low risk	"The patients and the investigators as well as anesthesiologists and nurses, were unaware of the patient grouping."
Blinding of healthcare providers (performance bias) All outcomes	Low risk	"The patients and the investigators as well as anesthesiologists and nurses, were unaware of the patient grouping."
Blinding of outcome assessor (detection bias) All outcomes	Low risk	"The patients and the investigators as well as anesthesiologists and nurses, were unaware of the patient grouping."
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants followed‐up to 24 h after surgery. "There were no dropouts among the 184 enrolled subjects."
Selective reporting (reporting bias)	High risk	Adverse effects of capsicum plaster not reported.
Other bias	Low risk	"The patients' characteristics, such as sex, age, weight, height, duration of anesthesia, history of PONV, history of motion sickness, nonsmoking status and intraoperative remifentanil use, were comparable between groups."