Majholm 2011.

Methods	Parallel‐group randomized trial, conducted in Denmark. Study conducted from May 2005 to December 2006.
Participants	134 healthy non‐smoking women undergoing breast surgery given total intravenous anaesthesia. Exclusions: pregnancy, women graded ASA physical status at least III, smoked or had comorbidities that could influence sensitivity in wrists and hands, skin problems at the location of wristband or had experienced nausea or vomiting within 24 h of surgery. Of the 134 participants, 22 withdrew, leaving 112 completing the study.
Interventions	Group 1: acupressure wristbands (Vital‐Band) placed on P6 acupoints just before induction and worn until 24 h after surgery, covered with dressing (n = 67). Group 2: sham acupressure wristbands with studs placed on dorsum of the forearm just before induction surgery and worn until 24 h after surgery, covered with dressing (n = 67).
Outcomes	Nausea (0 ‐ 24 h), vomiting (0 ‐ 24 h), risk of rescue antiemetic drug (0 ‐ 24 h), adverse effects associated with wristband.
Notes	P6 wristband adverse effects: 19/57 (redness), 7/58 (tenderness), 3/59 (paraesthesia), 8/59 (swelling). Sham wristband adverse effects: 20/53 (redness), 9/53 (tenderness), 1/53 (paraesthesia), 9/52 (swelling). Similar risk of adverse effects between groups for redness (P = 0.59), tenderness (P = 0.59), paraesthesia (P = 0.62) and swelling (P = 0.61). Manufacturer of Vital‐Band paid USD 9000 for testing of their device. 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	"Random allocation sequence was generated by drawing one of these sealed envelopes" and "In order to avoid staff members to figure out the randomization outcome of the last envelopes, we had more sealed randomization envelopes than needed according to the sample size calculation".
Allocation concealment (selection bias)	Low risk	"Randomized using opaque sealed envelopes".
Blinding of patients (performance bias) All outcomes	Low risk	"The wristband was covered with a dressing in such a way that both the patient and the outcome assessors were blinded and unable to discover in which position the acupressure wristband had been applied".
Blinding of healthcare providers (performance bias) All outcomes	Unclear risk	No details available.
Blinding of outcome assessor (detection bias) All outcomes	Low risk	"The wristband was covered with a dressing in such a way that both the patient and the outcome assessors were blinded and unable to discover in which position the acupressure wristband had been applied".
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reasons for 22 lost to follow‐up and discontinued intervention were given.
Selective reporting (reporting bias)	Low risk	All expected outcomes reported.
Other bias	Low risk	Baseline characteristics were comparable for preoperative factors (except history of PONV or motion sickness, or both), intraoperative factors and morphine use in the postoperative period.