CHARACTERISTICS OF STUDIES

Characteristics of included studies [ordered by study ID]

Agarwal 2000
Methods	Patients assigned to groups by a computer-generated table of random numbers. All acupressure wristbands were covered with gauze and tape. Outcome assessor blinded to treatment groups.
Participants	200 patients undergoing endoscopic urological surgery. Exclusion: patient refusal to participate in study, previous history of PONV and motion sickness, impaired renal function with increased urea and creatinine concentrations, diabetes mellitus, obesity, patients receiving antiemetic medication, histamine H2-receptor antagonist within 72 hours of surgery. No patient withdrew from the study.
Interventions	Acupressure wristband placed at P6 points on both forearms, applied 30 min before induction of anaesthesia and removed after 6 hours following surgery. Sham group was the spherical bead of acupressure wristbands placed on posterior surface, applied 30 min before induction of anaesthesia and removed 6 hours after surgery.
Outcomes	Nausea (0–24h), vomiting (0–24h), side effects of acupressure, risk of rescue antiemetic drug.
Notes	Rescue antiemetic was ondansetron 4 mg IV. No side effects or complications noted in either group.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Patients were assigned to two different groups according to a computer-generated table of random numbers”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	“No patient was excluded after admission to the study”.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable: “Patients were comparable in both the groups as regards to age, sex, height and weight”.
Blinding of patients? All outcomes	Unclear	Insufficient information.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Agarwal 2002
Methods	Patients assigned using a table of random numbers. Outcome assessor blinded to treatment groups. Acupressure and sham group received normal saline IV before induction to maintain blinding of the treatment groups.
Participants	150 adults undergoing laparoscopic cholecystectomy. Exclusion: patient refusal to participate in study, previous history of PONV and motion sickness, impaired renal function with increased urea and creatinine concentrations, diabetes mellitus, obesity, patients receiving antiemetic medication, histamine H2-receptor antagonist within 72 hours of surgery.
Interventions	Acupressure wristband placed at P6 points on both forearms, applied 30 min before induction of anaesthesia and removed after 6 hours following surgery (plus normal saline 1 mL IV just before induction of anaesthesia). Sham group was the spherical bead of acupressure wristbands placed on posterior surface, applied 30 min before induction of anaesthesia and removed 6 hours after surgery (plus normal saline 1 mL IV just before induction of anaesthesia). Antiemetic group was ondansetron 4 mg IV just before induction of anaesthesia (plus sham treatment outlined above).
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drug.
Notes	Rescue antiemetic was ondansetron 4 mg IV if patient vomited more than once. No side effects or complications noted in any of the groups. Data for outcome (0–24h) obtained by correspondence with author.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Patients were randomized into three groups of 50 each using a table of random numbers..”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 150 patients randomized.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable: “Patients were comparable in both the groups as regards to age, sex, height, weight and duration of surgery”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“The incidence of PONV was evaluated by a blinded observer”.
Alkaissi 1999
Methods	Method of allocation concealment not given. Patients were asked to record nausea and vomiting during their stay in hospital and after discharge. Nurses who asked the patients about nausea and administered antiemetics on the postoperative ward were not aware of treatment allocation or where the P6 acupoint was located.
Participants	60 women undergoing day case minor gynaecological surgery. Exclusion: patients undergoing local anaesthesia and those given prophylactic antiemetic during anaesthesia (n = 10, replaced by randomising another 10 patients at the end of the study).
Interventions	Acupressure wristband placed at P6 point on both forearms. Applied before surgery and left on for 24 hours. Draped with a dressing during the stay in the hospital. Sham acupressure applied to dorsal side of forearms. Applied before surgery and left on for 24 hours. Draped with a dressing during the stay in the hospital. Reference group were informed and anaesthetised in the same way as the other two groups.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drugs.
Notes	Rescue antiemetics were metoclopramide 10 mg IV at patient’s request; if not effective, then given droperidol 1.25 mg IV. Reference group received no treatment and was not included in data analysis.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons were given for 10 dropouts, who were replaced by randomising another 10 patients at the end of the study. “The dropouts were evenly distributed between the groups.” No missing data reported for 60 patients analysed.
Free of selective reporting?	No	Primary outcome (PONV) reported. Description of side effects not given.
Free of other bias?	Yes	Demographic data appeared to be comparable in Table 1.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“The nurses who asked the patients about nausea, and administered antiemetics on the postoperative ward were not aware of which treatment the patient received or where the P6 acupoint is located”.
Blinding of outcome assessor? All outcomes	Yes	“The nurses who asked the patients about nausea, and administered antiemetics on the postoperative ward were not aware of which treatment the patient received or where the P6 acupoint is located”. These nurses also noted vomiting episodes.
Alkaissi 2002
Methods	Patients randomized by sealed envelope (not opaque). Patients were asked to record nausea and vomiting. Multicentre trial. Wrists were wrapped with dressing to maintain blinding (but patients may have unwrapped the dressing).
Participants	410 women undergoing elective gynaecological surgery. No exclusion criteria specified. Thirty patients were withdrawn because they were: given local anaesthesia (n=12), or an antiemetic was given without the criteria for treatment of PONV being met (n=14), malignant hyperthermia (n=1), allergy to latex (n=2), and could not read Swedish (n=1). These 30 patients were replaced by another 30 at the end of the study period.
Interventions	Acupressure wristband placed on P6 point on both forearms just before start of anaesthesia, left on for 24 hours. Sham group included acupressure wristbands at non-acupoint on both forearms just before start of anaesthesia, left on for 24 hours. Reference group received no prophylactic treatment and was not blinded.
Outcomes	Nausea (0–24h), vomiting (0–24h), side effects of acupressure, risk of rescue antiemetic (type of drug not described)
Notes	Reference group received no treatment and was not included in data analysis. Adverse effects: wristbands felt uncomfortable, produced red indentation, or caused itching, headache and dizziness, or wrists hurt and tightness of wristband caused swelling or deep marks or blistering at site of stud.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons were given for 30 dropouts, who were replaced by randomizing another 30 patients at the end of the study. “Withdrawals were evenly distributed between the groups.” No missing data reported for 410 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Demographic data appeared to be comparable in Table 2.
Blinding of patients? All outcomes	Yes	“The wrists were wrapped for blinding”. Patients reported outcomes.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“The wrists were wrapped for blinding”. Patients reported outcomes.
Allen 1994
Methods	Method of allocation concealment not given. Outcome assessor was anaesthetist. Blinding not mentioned. No patient withdrew from study.
Participants	46 women undergoing gynaecological surgery. Exclusions: previous exposure to elasticised wristbands for the prevention of motion sickness.
Interventions	Acupressure wristband placed on P6 point of dominant arm before premedication (90 min before surgery). Duration of treatment not given. Sham acupressure wristband placed on dorsum of dominant wrist before premedication. Duration of treatment not given.
Outcomes	Nausea (0–24h), vomiting (0–24h).
Notes	Rescue antiemetic was prochlorperazine 12.5 mg IM 4 hourly when necessary. More than one dose of prochlorperazine data given (not included in data analysis).
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	“No patient refused to participate in the study, nor were there any withdrawals”.
Free of selective reporting?	No	Risk of rescue antiemetic drug (one or more dose) was not given in the results. Description of side effects not reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “The ages and weights of the patients in the two groups were comparable..”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar in patients with no previous experience with this form of acupressure.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Amir 2007
Methods	Method of allocation concealment was not given. Subjects were randomly assigned to groups using computer-generated random number table. Outcome assessor was blinded but no details about blinding for subjects and attending anaesthetist.
Participants	40 children and adults undergoing middle ear surgery. Patients with cardiovascular disease, central nervous system problems, previous history of PONV and/or motion sickness, and smokers were excluded. No details about withdrawals or loss to follow up.
Interventions	Group 1: electro-acupuncture at frequency of 4 Hz and current intensity increased to a degree just less than what caused discomfort, given 20 min before induction for duration of surgery. Group 2: sham electro-acupuncture. No details given except that patients experienced needle pricks.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drug (0–24h), risk of adverse effects.
Notes	Rescue antiemetic was ondansetron 4 mg IV after first episode of PONV and repeated when necessary at 6 hourly intervals. No side effects in sham electro-acupuncture group. Erythema occurred in 3 patients in the electro-acupuncture group.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Informed consent was taken from the selected patients and they were divided into two groups of twenty each using a computer-generated table of random numbers”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for the 20 patients randomized.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “Differences in mean age, weight, sex and duration of surgery were statistically insignificant”.
Blinding of patients? All outcomes	Unclear	Insufficient information.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“A blinded observed collected postoperative data of PONV”.
Andrzejowski 1996
Methods	Randomization by sealed envelope (not opaque). Patients asked to record nausea and vomiting.
Participants	36 women undergoing total abdominal hysterectomy. Exclusions: metal or elastoplast allergy, anticoagulant therapy, local skin disease at P6 acupoint or sham point, or chronic treatment with antiemetics.
Interventions	Semipermanent acupuncture needle inserted at P6 acupoint on both wrists 20 min before induction, left in place until second postoperative day. Sham semipermanent acupuncture needle inserted in sham point 20 min before induction, left in place until second postoperative day.
Outcomes	Nausea (0–8h), vomiting (0–8h), risk of antiemetic rescue drug, side effects.
Notes	Antiemetic rescue was prochlorperazine 12.5 mg IM when necessary. No side effects reported with interventions.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information. “Patients were allocated randomly into one of two groups”.
Allocation concealment?	Unclear	Insufficient information. “This was achieved by concealing the assignment schedule in sealed envelopes which were opened by the investigator just before inserting the needles”. Comment: not sure if envelopes were sequentially numbered and opaque.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 36 patients randomized.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There was no significant difference between the two groups in age, weight, total morphine consumed, or duration of anaesthesia”.
Blinding of patients? All outcomes	Yes	The assessments were made by the patients, who were blinded to their treatment“.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	The assessments were made by the patients, who were blinded to their treatment”.
Arnberger 2007
Methods	Patients were assigned to groups using a set of computer-generated random numbers. The assignments were kept in sealed, sequentially numbered envelopes. Patients and outcome assessors were unaware of group assignment. The attending anaesthetist could not be blinded to the group assignment but was not involved in outcome assessments.
Participants	220 females undergoing elective gynaecological and abdominal laparoscopic surgery of more than 1 hour duration. Exclusion: pregnant and breast-feeding women, and patients with eating disorders, obesity (body mass index > 35kg/m2), severe renal or liver impairment, central nervous system injury, vertebrobasilar artery insufficiency, vestibular disease, cytostatic therapy, and preoperative vomiting or antiemetic therapy. No patient withdrew from study.
Interventions	P6 group: during anaesthesia, neuromuscular blockade was monitored by a conventional nerve stimulator at a frequency of 1Hz over the median nerve (first electrode 1 cm proximal to P6 acupoint and second electrode placed 2 cm distal to the P6 acupoint) on the dominant hand. Sham group: during anaesthesia, neuromuscular blockade was monitored by a conventional nerve stimulator at a frequency of 1Hz over the ulnar nerve (first electrode 1 cm proximal to the point at which the proximal flexion crease of the wrist crosses the radial side of the tendon to the flexor carpi ulnaris muscle at the volar side of the wrist and second electrode placed 3 cm proximal to the distal electrode) on the dominant hand.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drug (0–24h), risk of adverse effects.
Notes	Rescue antiemetic was ondansetron 4 mg IV if 2 or more episodes of vomiting or persistent nausea; with repetition after 2 hours. No local irritation, redness, contact dermatitis or muscle ache (side effects) were recorded. Nausea (0–6h), vomiting (0–6h), and incidence of rescue antiemetic (0–6h) also reported.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“After induction of anaesthesia, patients were assigned to one of two groups using a set of computer-generated random numbers”.
Allocation concealment?	Yes	“The assignments were kept in sealed, sequentially numbered envelopes until used, and the envelope numbers with the assignment were recorded”.
Incomplete outcome data addressed? All outcomes	Yes	“Two hundred twenty patients were recruited for this study without any dropout over the observation period”.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “Demographic and morphometric characteristics and factors likely to influence PONV were similar in the two groups (Table 1)”.
Blinding of patients? All outcomes	Yes	“Patients and PONV evaluators were not informed of the group assignments”.
Blinding of healthcare providers? All outcomes	No	“The attending anaesthesiologist could not be blinded to the group assignment, but he or she was not involved with the PONV assessment”.
Blinding of outcome assessor? All outcomes	Yes	“Patients and PONV evaluators were not informed of the group assignments”.
Barsoum 1990
Methods	Randomization by ’envelope system’. No details about whether outcome assessor was blinded or not. Active and inactive acupressure wristbands were worn in the recovery room until discharge from hospital, or for seven days if that was sooner (exact duration of intervention in hours not reported).
Participants	162 patients undergoing general surgery. Ten patients withdrew because of language or age difficulty with completing analogue score, premature removal of wristbands, and incomplete follow-up data.
Interventions	Acupressure wristbands placed on P6 acupoint of both wrists in the recovery room. Sham acupressure wristbands (no studs) were applied to both wrists in the recovery room and antiemetics given only if clinically required. Antiemetic group was given prochlorperazine 12.5 mg IM with each postoperative opiate injection and when clinically required, and wore an acupressure band without stud on both wrists in the recovery room.
Outcomes	Vomiting (0–24h), risk of rescue antiemetic (prochlorperazine).
Notes	Nausea scores were reported for those patients who could not eat. Number of patients who were free of nausea was not given. Vomiting on postoperative day 2 and 3 also reported. Four patients reported some local tightness and discomfort (one of these experienced carpal tunnel like symptoms).
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals were given. No missing data reported for the 152 patients analysed.
Free of selective reporting?	No	Severity of nausea was reported but risk of nausea was not.
Free of other bias?	Yes	Baseline characteristics appeared to be comparable. “It can be seen that the groups were comparable with regard to the range of operation and anaesthetic agents used”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar and all patients were told that they were wearing wristbands to try to prevent PONV.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Butkovic 2005
Methods	Method of allocation concealment not given. “Researchers were double-blinded” but no specific details about how blinding was achieved.
Participants	120 children (5–14 years) undergoing hernia repair, circumcision, or orchidopexy. Exclusion: patients predisposed to nausea and vomiting secondary to gastroesophageal reflux, motion sickness, and inner ear or central nervious system disorders.
Interventions	Group 1: laser acupuncture on P6 acupoint bilaterally for 1 min, 15 min before induction of anaesthesia and IV infusion of saline. Group 2: metoclopramide 0.15mg/kg IV and sham laser on P6 acupoint bilaterally for 1 min, 15 min before induction of anaesthesia. Group 3: sham laser stimulation on P6 acupoint bilaterally for 1 min, 15 min before induction of anaesthesia and saline infusion.
Outcomes	Vomiting (0–2h), risk of rescue antiemetic drug.
Notes	Rescue antiemetic was ondansetron 0.1 mg/kg IV if vomiting was severe.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for the 120 children analysed.
Free of selective reporting?	No	Description of side effects not included. Nausea not reported because it may be difficult to assess in children.
Free of other bias?	Yes	Baseline characteristics were comparable. “Demographic data showed no significant difference among groups”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make intervention appear similar.
Blinding of healthcare providers? All outcomes	Yes	“Researchers were double-blinded” but no specific details about how blinding was achieved. Comment: probably done.
Blinding of outcome assessor? All outcomes	Yes	“Researchers were double-blinded” but no specific details about how blinding was achieved. Comment: probably done.
Duggal 1998
Methods	A table of random numbers was used to allocate patients into treatment groups. Patient, anaesthetist, and investigators were unaware of treatment groups during the study. Patients recorded outcome measures on a questionnaire.
Participants	263 patients undergoing spinal anaesthesia for elective Caesarean delivery. Excluded: patients with a history of hyperemesis gravidarum or if they had received antiemetic medication during the 48h before surgery. Eight women excluded for failing to wear wristbands for 10 hours, three had received prophylactic antiemetics, and eight were not given standard combination of intrathecal drugs (total 19 withdrawals).
Interventions	Acupressure wristbands were applied to both wrists just before induction of spinal anaesthesia and worn for 10 hours. Sham acupressure wristbands were applied at P6 acupoint (but stud missing) on both wrists just before induction of spinal anaesthesia and worn for 10 hours.
Outcomes	Nausea (0–10h), vomiting (0–10h), risk of rescue antiemetic (type of drug not given), side effects of acupressure.
Notes	Adverse effects of acupressure wristbands: tightness, swollen hands, problems with infusion, itching wrists. Intraoperative nausea and vomiting reported.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“A table of random numbers was used to allocate patients to one of two groups”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals were given. No missing data reported for the 244 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “Demographic analysis revealed no statistically significant difference between subjects in the two groups (Table 1)”.
Blinding of patients? All outcomes	Yes	“The nature of the bands was therefore unknown to the patient, anaesthetist and investigators for the duration of the study”.
Blinding of healthcare providers? All outcomes	Yes	“The nature of the bands was therefore unknown to the patient, anaesthetist and investigators for the duration of the study”.
Blinding of outcome assessor? All outcomes	Yes	“The nature of the bands was therefore unknown to the patient, anaesthetist and investigators for the duration of the study”.
Dundee 1986
Methods	Method of allocation concealment not given. Outcome assessor was blinded to treatment groups.
Participants	75 women undergoing minor gynaecological surgery.
Interventions	Group 1: acupuncture at P6 acupoint with 5 min manual stimulation (1.2 cm 30 gauge needle) after premedication with nalbuphine 10 mg. Group 2: sham acupuncture at a dummy point on lateral elbow crease with 5 min manual stimulation (1.2 cm 30 gauge needle) after premedication with nalbuphine 10 mg. Group 3: no further treatment after premedication with nalbuphine 10 mg.
Outcomes	Nausea (0–6h), vomiting (0–6h), side effects of treatment.
Notes	No side effects noted in either group. Group 3 data were excluded from data-analysis. Presence or absence of needle marks and its location may have been observed by the outcome assessor.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 75 patients analysed.
Free of selective reporting?	Unclear	No details about the use of rescue antiemetic in anaesthetic protocol. The risk of rescue antiemetic drug not reported.
Free of other bias?	Yes	“The groups were comparable in average age, weight, and duration of anaesthesia”.
Blinding of patients? All outcomes	Yes	The authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“Their assessments were performed by an observer who was unaware of which patients had undergone acupuncture”.
Dundee 1989
Methods	Method of allocation concealment not given. Outcome assessor was blinded to treatment group, except where the patient pointed to the P6 acupoint site.
Participants	155 women undergoing minor gynaecological surgery.
Interventions	Acupuncture at P6 acupoint with 5 min manual stimulation after premedication. Electroacupuncture at P6 acupoint for 5 min after premedication. Antiemetic group 1 had cyclizine 50 mg IM after premedication. Antiemetic group 2 had metoclopramide 10 mg IM after premedication. Reference group had no treatment.
Outcomes	Nausea (0–6h), vomiting (0–6h), side effects of treatment.
Notes	For data analysis purposes, manual acupuncture and electro-acupuncture were combined. Reference group received no treatment and was not included in data analysis. This paper reported both controlled and uncontrolled studies of P6 stimulation. Used original data from Dundee JW, Fitzpatrick KTJ, Ghaly RG. Is there a role for acupuncture in the treatment of postoperative nausea and vomiting? Anesthesiology 1987; 67: 3A P165. This trial appears to be a duplicate of a previous published study: Ghaly RG, Fitzpatrick KTJ, Dundee JW. Antiemetic studies with traditional Chinese acupuncture-a comparison of manual needling with electrical stimulation and commonly used antiemetics. Anaesthesia 1987; 42:1108–10 (note that metoclopramide group was not included in this trial, but the results of other groups are the same). According to the authors, there were no side effects associated with acupuncture groups but some patients complained of drowsiness following antiemetic drug administration. For data analyses, manual acupuncture group was compared with cyclizine, and electroacupuncture group was compared with metoclopramide.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 155 patients analysed.
Free of selective reporting?	Unclear	No details about the use of rescue antiemetic in anaesthetic protocol. The riisk of rescue antiemetic drug not reported.
Free of other bias?	Unclear	Demographic comparisons between groups were not given.
Blinding of patients? All outcomes	Unclear	Insufficient information.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“Patients were visited at 1 h and 6 h after operation by a person who was unaware of the preoperative treatment”.
Fassoulaki 1993
Methods	Method of allocation concealment not given. Transcutaneous electrical nerve stimulator, active or inactive, was covered with dark plastic bags. Outcome assessor was blinded to treatment allocation.
Participants	106 women undergoing abdominal hysterectomy. Three patients in the sham group were excluded because they were given metoclopramide in the postoperative period for persistent vomiting (but this data was included for risk of rescue antiemetic given analysis).
Interventions	Transcutaneous electrical nerve stimulation on the P6 acupoint was applied 30–45 min before induction and continued for 6 hours postoperatively. Sham group was treated the same way but with the electrical stimulator turned off.
Outcomes	Vomiting (0–2h) without antiemetic rescue, risk of rescue antiemetic (metoclopramide).
Notes	Potential bias if outcome assessor removed plastic bag covering the stimulator. Reported vomiting 2–4h, 4–6h, 6–8h intervals. No data on vomiting (0–8h).
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	No	“Three patients, originally assigned to the control groups, who received postoperatively metoclopramide because of persistent vomiting were eliminated from further vomiting evaluation and consequently from the study”. Comment: may introduce clinically relevant bias in summary effect measure.
Free of selective reporting?	No	Nausea and side effects were not reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “The two groups did not differ in age, body weight, duration of anaesthesia, and duration of surgery (Table 1)”.
Blinding of patients? All outcomes	Yes	“The stimulator, active or inactive, was covered with dark plastic bags, not allowing distinction between active and inactive stimulators”.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	Vomiting was assessed by “an independent observer who was unaware of the patient randomization and of TENS treatment”.
Ferrara-Love 1996
Methods	Allocation was done by birth date with even numbered months and days assigned to the treatment group, odd months and days assigned to the sham acupressure group, and combinations of even/odd months and days assigned to the no treatment group. Recovery room nurses were blinded to patients with acupressure and sham acupressure wristbands.
Participants	136 adults undergoing orthopaedic, general, plastic, and ’other’ surgery. Forty-six patients excluded after randomisation for failure to meet inclusion criteria.
Interventions	Group 1: acupressure wristbands placed on P6 acupoint during surgery until hospital discharge. Group 2: sham acupressure wristbands without studs placed on P6 acupoint during surgery until hospital discharge. Group 3: reference group had no acupressure treatment.
Outcomes	Nausea in the operating room after surgery, risk of rescue antiemetic drugs in the operating room if nausea persisted and/or emesis occurred.
Notes	No treatment group excluded from data analysis. No cumulative outcome data.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	No	“Randomization was done by birth date with even numbered months and days assigned to the treatment group, odd months and days assigned to the placebo group and combinations of even/odd months and days assigned to the control group”.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for the 90 patients analysed.
Free of selective reporting?	No	Risk of vomiting and side effects were not reported in the results.
Free of other bias?	Yes	Baseline characteristics were comparable. “There were no differences between groups in demographic and perioperative variables” as tested using appropriate univariate statistical tests.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	PACU staff were blinded.
Blinding of outcome assessor? All outcomes	Yes	“Incidence of postoperative nausea and vomiting was documented by the PACU staff who were blinded as to treatment and placebo group”.
Gan 2004
Methods	Randomization by random number generator in a sealed envelope technique. To maintain patient blinding, sham surface electrodes placed on P6 bilaterally but electrical stimulation unit not turned on. Electrical stimulation unit screen was covered with an opaque tape in all groups so that clinicians, research personnel, and patients were unaware if the unit was on or off. Study medication prepared by pharmacists, not involved in study. Postoperative data collected by research nurse not involved in management of patients.
Participants	77 patients undergoing major breast surgery. Exclusion: pregnancy, using permanent cardiac pacemaker, previous experience of acupuncture therapies, received any antiemetic medication or had nausea, vomiting or retching within 24 hours of surgery. Two patients withdrew from study.
Interventions	Group 1: ondansetron 4 mg IV given at induction of anaesthesia and sham electro-acupoint stimulation at P6 acupoints (30 to 60 min before induction and continued to the end of surgery). Group 2: electro-acupoint stimulation at P6 bilaterally (30 to 60 min before induction and continued to the end of surgery) and saline IV given at induction of anaesthesia. Group 3: sham electro-acupoint stimulation at P6 bilaterally (30 to 60 min before induction and continued to the end of surgery) and saline IV given at induction of anaesthesia.
Outcomes	Nausea (0–2h), vomiting (0–2h), risk of rescue antiemetic drug, adverse effects.
Notes	Rescue antiemetic was dexamethasone 8 mg IV when patient’s nausea score > 5 out of 10 for 15 min or longer, 2 emetic episodes within 15 min, or at patient’s request. No redness residue on acupoint site in any groups.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Randomization was achieved using a random number generator..”.
Allocation concealment?	Yes	“…In a sealed envelope technique”. “Study drugs were prepared by the pharmacists not directly involved in the study..”. Comments: the authors appeared to take steps to minimize inadequate allocation concealment.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals were given. No missing data reported for the 75 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There was no difference in patient demographics among the groups (Table 1)”.
Blinding of patients? All outcomes	Yes	“All patients were also told that the device produced an electrical current that they may or may not feel. The screen on the unit (measuring 4 × 2 cm) was covered with an opaque tape in all groups so that the clinicians and research personnel were unaware if the unit was on or off ”.
Blinding of healthcare providers? All outcomes	Yes	“All patients were also told that the device produced an electrical current that they may or may not feel. The screen on the unit (measuring 4 × 2 cm) was covered with an opaque tape in all groups so that the clinicians and research personnel were unaware if the unit was on or off ”.
Blinding of outcome assessor? All outcomes	Yes	“Postoperative data were collected by a separate research nurse not involved in the preoperative or intraoperative management of patients”.
Gieron 1993
Methods	Method of allocation concealment not given. Outcome assessor knew what treatment group the patient belonged to.
Participants	90 Women undergoing gynaecological operations (6–8h).
Interventions	Group 1: acupressure was carried out by fastening small metal bullets at the P6 acupoint to each wrist by an elastic bandage on the morning of the operation and left on for 24h. Group 2: sham acupressure carried out by applying elastic bandage to P6 acupoint on the morning of the operation and left on for 24h. Group 3: no treatment.
Outcomes	Nausea (0–6h), vomiting (0–6h), risk of rescue antiemetic (metoclopramide).
Notes	No treatment data were excluded from analysis. Also reported separate incidences of nausea and vomiting (0–1h) and (6–24h). No side effects identified in the trial.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 90 patients analysed.
Free of selective reporting?	Yes	All expected outcomes were reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “The anthropometric data, the duration of surgery and the amount of postoperative analgesia were comparable between the three groups”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	No	The outcome assessor was not blinded.
Habib 2006
Methods	Method of allocation concealment unclear. For blinding, the transcutaneous acupoint electrical stimulation was covered with opaque gauze that was taped to the wrist. Outcome assessor blinded.
Participants	94 Women undergoing Caesarean delivery under spinal anaesthesia. Exclusion: previous experience of acupuncture or acu-stimulation, had experienced vomiting or retching within 24 h before surgery, had taken on antiemetic or a glucocorticoid within 24 h before surgery, or had an implanted pacemaker or defibrillator device. Three patients withdrew from study because of protocol violations.
Interventions	Transcutaneous acupoint electrical stimulation device on P6 acupoint of the dominant hand 30 to 60 min before surgery. Patients asked to wear wristband for 24 h after surgery. Sham transcutaneous acupoint electrical stimulation device on dorsum of wrist of the dominant hand 30 to 60 min before surgery. Patients asked to wear wristband for 24 h after surgery.
Outcomes	Postoperative nausea (0–24h), postoperative vomiting (0–24h), risk of rescue antiemetic.
Notes	Intraoperative nausea and vomiting data reported in the paper. Rescue antiemetic was ondansetron 4 mg IV if nausea score was 6 or more, or at patient’s request.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficent information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals given. No missing data reported for 91 patients analysed.
Free of selective reporting?	No	Side effects not reported
Free of other bias?	Yes	Baseline characteristics were comparable. “The two groups were similar with respect to demographics, parity, history of PONV or motion sickness, smoking status, duration of surgery, blood loss, intraoperative fluids, intraoperative IV fentanyl, intraoperative IV ephedrine, treatment for pruritus, and consumption of oxycodone/acetaminophen tablets (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar. “For blinding, the ReliefBand was covered with opaque gauze that was taped to the wrist”.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“A separate researcher who was unaware of the patient’s randomisation collected that data…”.
Harmon 1999
Methods	Randomization was conducted by computer and the code was sealed (not opaque) until arrival of patient in the operating theatre. Outcome assessor was blinded to treatment groups.
Participants	104 Women undergoing laparoscopy and dye investigation. Exclusions: obesity, diabetes mellitus, and previous history of PONV.
Interventions	Acupressure on P6 acupoint of right wrist, applied immediately before induction for 20 min, removed before end of surgery. Placebo acupressure on non-acupoint site, applied before induction for 20 min and removed before end of surgery.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drugs.
Notes	Rescue antiemetic was ondansetron 4 mg IV and prochlorperazine 12.5 mg IM. No side effects in either group noted. Some patients did not have outcome data.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Randomization was conducted by computer..”.
Allocation concealment?	Unclear	“…And the code was sealed until arrival of the patient in the operating theatre”. Comment: not sure whether envelopes were sequentially numbered and opaque.
Incomplete outcome data addressed? All outcomes	No	In acupressure group (n=52), missing nausea and vomiting data in 8 and 5 patients respectively. In sham group (n=52), missing nausea and vomiting data in 13 and 5 patients respectively.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “The groups were comparable in age, weight and duration of surgical procedure (Table 1)”.
Blinding of patients? All outcomes	Yes	“Both patients and nurses were unaware of patient group allocation”.
Blinding of healthcare providers? All outcomes	Yes	“Both patients and nurses were unaware of patient group allocation”.
Blinding of outcome assessor? All outcomes	Yes	“..An anaesthetist blinded to the therapy registered whether nausea, retching or vomiting had occurred”.
Harmon 2000
Methods	Method of allocation concealment was not given. Acupressure wristbands and placebo acupressure wristbands were covered with surgical drapes to prevent anaesthetist from identifying which group the patient was allocated to. Patients might have guessed which group they were in as there was no attempt to conceal the wristband. Authors claimed that the outcome assessor was blinded to treatment group.
Participants	94 Healthy women (18 to 40 years) undergoing elective Caesarean section. Excluded: previous history of PONV, nausea and vomiting in previous 24 hours, obesity (body mass index > 35), diabetes mellitus, or previous experience of acupuncture or acupressure.
Interventions	Acupressure on P6 acupoint on right wrist, applied 5 min before administration of spinal anaesthesia, removed just before assessment 6 hours after discharge to the ward. Placebo acupressure on non-acupoint site, applied 5 min before administration of spinal anaesthesia, removed just before assessment 6 hours after discharge to the ward.
Outcomes	Nausea (0–24h), vomiting (0–24h).
Notes	Reported separate incidence of intraoperative nausea and vomiting. Rescue antiemetic was ondansetron 4 mg IV during operations, or cyclizine 50 mg IM 8 hourly after operations. Rescue antiemetic use reported as mean dose (no data for risk of rescue cyclizine use). Side effect of acupressure bands was “some localized discomfort in a small number of women”.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals were given. No missing data reported for 94 patients analysed.
Free of selective reporting?	No	Risk of rescue cyclizine not reported separately for nausea and vomiting outcomes.
Free of other bias?	Yes	Baseline characteristics were comparable. “The groups were comparable with respect to age, weight, height and bupivacaine dose (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“Bands were not visible to the assessing anaesthetist during operations, as patients’ arms were covered with surgical drapes”.
Blinding of outcome assessor? All outcomes	Yes	“After 6 and 24h, an anaesthetist blinded to the therapy noted whether nausea, retching or vomiting had occurred”.
Ho 1989
Methods	Method of allocation concealment not given. No details about whether the outcome assessor was blinded to treatment groups or not.
Participants	100 Women undergoing laparoscopy.
Interventions	Group 1: electro-acupuncture applied at P6 acupoint on right wrist for 15 min in the recovery room. Group 2: transcutaneous electrical nerve stimulation at P6 acupoint on right wrist for 15 min in the recovery room. Group 3: antiemetic group was given prochlorperazine 5 mg IV. Group 4: no treatment.
Outcomes	Vomiting (0–3h), side effects of treatment groups.
Notes	Reference group received no treatment and was not included in data analysis. Groups 1 and 2 were combined for data analysis. Side effect of electro-acupuncture were sleepiness and feeling tired.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data was reported for the 100 patients analysed.
Free of selective reporting?	No	Only vomiting was reported. Authors should have assessed nausea in women and the risk of rescue antiemetic drugs.
Free of other bias?	Yes	Baseline characteristics were comparable. “The age, weight, and duration of anaesthesia did not differ significantly among the groups (Table 1)”.
Blinding of patients? All outcomes	Unclear	Insufficient information.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Ho 1996
Methods	Randomization conducted by computer, with each code sealed in an envelope (not opaque) to be opened before induction of spinal anaesthesia. Outcome assessor was blinded to treatment groups.
Participants	60 Women receiving epidural morphine for post-Caesarean section pain relief. Excluded: previous carpal tunnel syndrome, or those who had experienced nausea or vomiting within 24 h before Caesarean section.
Interventions	Group 1: acupressure wristbands on P6 acupoint of both wrists before administration of spinal anaesthesia. Worn for 48 hours. Group 2: sham acupressure wristbands on both wrists but plastic button was blunted in order not to exert pressure on P6 acupoint. Worn for 48 hours.
Outcomes	Nausea (0–48h), vomiting (0–48h), risk of rescue antiemetic drug, side effects of acupressure wristbands.
Notes	Rescue antiemetic was metoclopramide. No side effects were noted.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Randomization was conducted by computer..”.
Allocation concealment?	Unclear	“…With each code sealed in an envelope to be opened upon the parturient’s arrival in the operating room”. Comment: not sure if envelopes were sequentially numbered and opaque.
Incomplete outcome data addressed? All outcomes	Yes	“All parturients completed the trial and tolerated the bands well”.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There were no statistically significant difference with respect to age, weight, height, duration of operation, intraoperative blood loss, duration of pain relief, total epidural morphine dosage, percentage of parturients requiring additional analgesics and total time spent wearing bands between the two groups”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“An independent anaesthesiologist blinded to the parturient groups followed up all parturients”.
Klein 2004
Methods	Patients randomized by computer-generated random number tables to either acupressure or sham groups. Both groups had acupressure bands covered by a soft cotton roll to ensure blinding. Anaesthetist caring for the patient was not aware of the group allocation. Outcome assessor blinded to treatment allocation.
Participants	152 Patients undergoing coronary artery bypass graft or valvular surgery. Exclusion: past history of hiatus hernia, heartburn, or previous gastric surgery, morbid obesity, taking antiemetic medications, H2 receptor antagonist, or proton pump inhibitors. No details about withdrawals or loss to follow up.
Interventions	Acupressure wristbands on P6 acupoint on both wrists before induction of anaesthesia, removed 24 h after extubation. Sham acupressure wristbands on P6 acupoint of both wrists before induction of anaesthesia, removed 24 h after extubation. Sham group had band without a bead placed on P6 acupoint.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drug, risk of adverse effects.
Notes	Rescue antiemetic was dimenhydrinate 50 mg IV for patients who reported moderate or severe nausea, or who experienced retching or vomiting. No significant adverse effects reported in either group.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Patients were randomized by computer-generated random number tables to either acupressure or placebo control groups”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for the 152 patients analysed.
Free of selective reporting?	Yes	Reported all expected outcomes.
Free of other bias?	Yes	Baseline characteristics were comparable. “There were no differences between the 2 groups with regard to demographic data and surgical characteristics (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“The anaesthesiologist caring for the patient was not aware of group allocation”.
Blinding of outcome assessor? All outcomes	Yes	“All patients were assessed for nausea and vomiting by nursing staff in the intensive care unit, who were unaware of treatment allocation”.
Lewis 1991
Methods	Method of allocation concealment was not given. Outcome assessor was blinded. Acupressure wristbands were worn for approximately 4 hours.
Participants	66 Children undergoing strabismus correction surgery. Excluded: children with anatomical or neurological abnormalities of the upper limbs. Two children lost to follow up.
Interventions	Group 1: acupressure wristbands placed on P6 acupoints 1 hour before surgery and worn until discharge from hospital. Group 2: sham acupressure wristbands without studs placed on P6 acupoints 1 hour before surgery and worn until discharge from hospital.
Outcomes	Vomiting (0–24h), risk of rescue antiemetic drug, side effects.
Notes	Both types of wristbands were identical unless turned inside out. Rescue antiemetic was droperidol 0.02 mg/kg IV for vomiting. No side effects reported.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Two patients in acupressure group had incomplete data. Comment: unlikely to have a clinically relevant impact on summary estimate.
Free of selective reporting?	No	Although nausea was an outcome collected in the methods section it was not reported in the results because nausea may be difficult to assess in children.
Free of other bias?	Yes	Baseline characteristics were comparable. “There were no significant differences between the two groups in their patient characteristics (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	The anaesthetic staff were blinded.
Blinding of outcome assessor? All outcomes	Yes	“A second blinded investigator recorded all other perioperative data, including the incidence of postoperative nausea and vomiting in the recovery areas”.
Liu 2008
Methods	Method of allocation concealment not given. Anaesthetist and the outcome assessor were blinded.
Participants	96 Patients undergoing laparoscopic cholecystectomy who were aged 18 to 60 years. Exclusions: pregnancy, women experiencing menstrual symptoms, patients with permanent cardiac pace-maker, previous experience with acupuncture therapies before surgery, received antiemetics or experienced nausea, vomiting, or retching within 24 h of surgery. No patients withdrew from study.
Interventions	Group 1: transcutaneous electro-acupoint stimulation using a peripheral nerve stimulator at P6 (2–100 Hz, 50 ms, 0.5–4mA) applied 30 to 60 min before induction of anaesthesia, and continued to the end of surgery. Group 2: inactive device with similar electrode for transcutaneous electro-acupoint stimulation using a peripheral nerve stimulator at P6 applied 30 to 60 min before induction of anaesthesia, and continued to the end of surgery.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drug (0–24h), adverse effects of transcutaneous electro-acupoint stimulation.
Notes	Rescue antiemetic drug was ondansetron 4 mg IV, to patients who had a nausea score of more than 5 on a 10 point scale, vomited twice within 15 min, or at the patient’s request. P6 acupoint stimulation was associated with a reduction in the risk of severe nausea (Group 1: 2/48 versus Group 2: 14/48). No redness, swelling, itching, and pain, or other relevant complications at P6 acupoint in the two groups.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Patients were randomized into two groups of 48 in each using a table of random numbers”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	“All 96 patients completed the study”.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “As shown in Table 1 and Table 2, the patients’ gender, age, weight, ASA physical status, previous PONV history, duration of surgery or anaesthesia, transfusion amount, operative procedure and doses of opioids in the two groups were not significantly different”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“The anesthesiologists and care providers were blinded to the study group”.
Blinding of outcome assessor? All outcomes	Yes	“Postoperative data were collected by a separate research nurse who was not aware of the preoperative or perioperative management of patients”.
Misra 2005
Methods	Method of allocation concealment was not given. Subjects were randomly assigned to groups using computer-generated random number table. Patient, anaesthetist, and the outcome assessor were blinded.
Participants	123 Adults (18–52y) undergoing middle ear surgery. Exclusion: pregnancy, obesity, diabetes mellitus, impaired renal or liver functions; patients who had taken H2 antagonists, antiemetics, or psychoactive medication; or had nausea, retching, or vomiting within 48 h before surgery. Three patients withdrew because: they required administration of dexamethasone (n=2), and facial nerve injury (n=1).
Interventions	Group 1: sham plaster 1cm × 1cm patch affixed to P6 acupoint on both forearms 30 min before induction of anaesthesia and normal saline IV at the end of surgery. Plasters removed 6 h after surgery. Group 2: capsicum plaster containing capsicum oleoresin 1% w/w 1cm × 1cm patch affixed to P6 acupoint on both forearms 30 min before induction of anaesthesia and normal saline IV at the end of surgery. Plasters removed 6 h after surgery. Group 3: sham plaster 1cm × 1cm patch affixed to P6 acupoint on both forearms 30 min before induction of anaesthesia and ondansetron 4 mg IV at the end of surgery. Plasters removed 6 h after surgery.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drug (0–24h), adverse effects of plaster.
Notes	Nausea (0–6h), vomiting (0–6h), incidence of rescue antiemetic (0–6h) also reported. Rescue antiemetic was ondansetron 4 mg IV for patients with persistent nausea for more than 5 min, two or more episodes of vomiting/retching, or at patient’s request for PONV treatment. “One patient complained of mild irritation at the site of capsicum plaster application. No other adverse effects attributable to acu-stimulation or ondansetron were observed”.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“The subjects were randomly assigned to one of the three groups using a computer-generated random number table”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals given. No missing data reported for the 120 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “The demographic characteristics of the three groups were similar, as were history of previous PONV and motion sickness”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“Anesthesia was standardized and given by an anesthesiologist blinded to group assignment”.
Blinding of outcome assessor? All outcomes	Yes	“The incidence of PONV was evaluated within six hours and 24 hr after transfer to the postoperative unit by a blinded observer”.
Rusy 2002
Methods	Randomized block design procedure was used. Arms were covered with full-length soft restraints so the needle positions could not be seen. Recovery room nurses were blinded to treatment groups. Patients were asked to record nausea and vomiting over 24h after discharge from hospital.
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. One child disqualified after enrolment when propofol was administered during the anaesthetic.
Interventions	Electro-acupuncture at P6 for 20 min after patient was awake. Sham electro-acupuncture at P2 for 20 min after patient was awake. Sham reference group had no needles inserted. Insulated wires were attached to insides of arm and stimulation box was activated to maintain blinding.
Outcomes	Vomiting (0–24h), nausea (0–24h), risk of rescue antiemetic drugs.
Notes	Rescue antiemetics were ondansetron and droperidol IV. Sham electro-acupuncture and sham reference group data were combined.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“A randomized block design procedure was used to assign enrollees to one of three groups..”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reason for withdrawal of one patients was given. No missing data reported for 120 patients analysed.
Free of selective reporting?	Unclear	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”.
Free of other bias?	Yes	Baseline characteristics were comparable. “The groups were similar for age, sex, weight, analgesics administered, and surgical time (Table 1), with no differences found”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“Experienced recovery room nurses, who were blinded to the treatment group, assessed nausea and vomiting”.
Blinding of outcome assessor? All outcomes	Yes	“Experienced recovery room nurses, who were blinded to the treatment group, assessed nausea and vomiting”.
Samad 2003
Methods	Patients randomly assigned by random table number. Blinded observer evaluated outcomes. Unclear whether patients were blinded as the wristband was not covered by gauze. Anaesthetist caring for the patient was most likely to be blinded as the intervention was given by investigators not involved with patient care.
Participants	50 Male and female patients (18–60y) undergoing laparoscopic cholecystectomy. Exclusion: obesity (weight > 80 kg), diabetics, patients with history of postoperative nausea and vomiting, patients receiving antiemetics and histamine H2 antagonists.
Interventions	Acupressure band on right hand at P6 acupoint half an hour before induction of anaesthesia, and kept on for 6 hours after surgery. Sham acupressure band on right hand with plastic bead placed on the dorsum of forearm.
Outcomes	Nausea (0–6h), vomiting (0–6h), risk of rescue antiemetic drug, side effects.
Notes	Rescue antiemetic was metoclopramide 10 mg IV for nausea or vomiting. No side effects or complications associated with either intervention.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Patients were randomly assigned by random table number to either group..”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 50 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There was no statistically significant difference with respect to age, sex, weight and duration of surgery between the two groups (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	“A blinded observer in the recovery room (one of the investigator not involved in applying acupressure band) evaluated the patients for presence of nausea and vomiting…”.
Schlager 1998
Methods	Method of allocation concealment not given. Risk of vomiting recorded by nursing staff in the recovery room and on the ward.
Participants	40 Children (3 to 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 minutes before induction of anaesthesia and 15 minutes after arriving in the recovery room. Sham laser stimulation held on P6 acupoints but laser beam not activated, 15 minutes before induction of anaesthesia and 15 minutes after arriving in the recovery room.
Outcomes	Vomiting (0–24h), 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 (0–2h, 0–6h) also recorded in the paper.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 40 children analysed.
Free of selective reporting?	Unclear	Risk of nausea was not recorded because it may be difficult to assess in children. Authors stated that “stimulation of P6 with a low-level laser has no known side effects”.
Free of other bias?	Yes	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)”.
Blinding of patients? All outcomes	Yes	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? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Schultz 2003
Methods	Study envelopes with the group allocations were prepared by the principal investigator and the study pharmacist using a random number table. The envelopes were opened by the admitting nurse. Nurses were taught how to apply the acupressure bands by a member of the research team. Registered nurses documented outcomes.
Participants	103 Women undergoing gynaecological surgery. Exclusions: pregnancy, surgery for cancer within the previous 5 years, chemotherapy or radiation therapy within 5 years, an antiemetic within 24 hours before surgery, previous use of acupressure bands, or peripheral neuropathy. 40 women withdrew before completion of trial due to non-administration of study drug and change in postoperative plans due to earlier hospital discharge.
Interventions	Group 1: droperidol 1.25 mg IV at induction and acupressure wristband at P6 acupoint on both wrists before surgery (worn up to 48 hours after surgery). Group 2: droperidol 1.25 mg IV at induction and sham acupressure wristband at P6 acupoint on both wrists before surgery (worn up to 48 hours after surgery). Sham acupressure wristband had flat button which did not exert pressure on P6 acupoint. Group 3: normal saline IV at induction and acupressure wristband at P6 acupoint on both wrists before surgery (worn up to 48 hours after surgery). Group 4: normal saline IV at induction and sham acupressure wristband at P6 acupoint on both wrists before surgery (worn up to 48 hours after surgery).
Outcomes	Nausea (0-duration of hospital stay), vomiting (0-hospital stay).
Notes	Authors replied to our request for unpublished data for incidence of nausea and vomiting during hospital stay.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	Used random number table.
Allocation concealment?	Yes	“Study envelopes with the appropriate acupressure band and drug preparation were prepared by the principal investigator and the study pharmacist…. The packets were kept in a secure area of the surgical admitting department. The envelope, containing the study group designation, was opened by the admitting nurse…”.
Incomplete outcome data addressed? All outcomes	No	Although 40 women withdrew from the study, reasons were given. “There was no statistically significant difference in the age of the 103 women who continued in the study as compared with 40 women who did not complete the study”. Of the 103 women recruited, 95 and 62 women had complete data for nausea and vomiting during hospital stay respectively. Comment: missing data likely to bias the summary effect measure.
Free of selective reporting?	No	Risk of side-effects and use of rescue antiemetic drugs were not described in the paper.
Free of other bias?	Yes	Baseline characteristics appeared to be comparable. There was no difference among the groups for age, type of surgery, duration of surgery, duration of acupressure wristband use.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Sharma 2007
Methods	Method of allocation concealment not given. No blinding.
Participants	60 Women undergoing laparoscopic cholecystectomies under general anaesthesia. Exclusion: obesity, previous history of PONV and motion sickness.
Interventions	Group 1: ondansetron 4 mg IV given 10 min after induction of anaesthesia. Group 2: bilateral P6 acupuncture 5 minutes before induction of anaesthesia. Intermittent stimulation was given at P6 acupoints by rotating needle clockwise and anticlockwise up to 30 min. Group 3: combination of group 1 and group 2 interventions.
Outcomes	Nausea (0–7h), vomiting (0–7h), risk of rescue antiemetic drug (0–7h), risk of adverse effects.
Notes	Rescue antiemetic was metoclopramide 10 mg IV. Data in group 3 was not used in any of the meta-analyses. No pain, bleeding, vasovagal attack, or broken acupuncture needles noted in any of the groups.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 60 women analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There was no significant difference among the patients in both the groups regarding weight, age, height, gender, hours of preoperative fasting and duration of anesthesia and surgery…”.
Blinding of patients? All outcomes	No	“Blinding of any form was not possible because acupuncture needles had to be kept in situ in the operating room”.
Blinding of healthcare providers? All outcomes	No	“Blinding of any form was not possible because acupuncture needles had to be kept in situ in the operating room”.
Blinding of outcome assessor? All outcomes	No	“Blinding of any form was not possible because acupuncture needles had to be kept in situ in the operating room”.
Shenkman 1999
Methods	Method of allocation concealment not given. Recovery room nurses and ward nurses were blinded to treatment groups. P6 acupoints and sham points on all patients were covered with opaque adhesive tape.
Participants	100 Children (2–12 years) undergoing tonsillectomy. Exclusion: congenital heart disease or significant pulmonary disease, predisposition for emesis or actual emesis in the 24 hours before surgery, use of medications with antiemetic effects within the 24 hours before surgery, infection over an acupuncture point, need for postoperative intubation for more than 1 hour, and severe obstructive sleep apnoea.
Interventions	Group 1: acupressure wristband on P6 acupoints of both wrists applied before premedication. Immediately after induction of anaesthesia, wristbands were removed and acupuncture needles were inserted at P6 acupoint on both wrists, left in place until next day. Needles were secured with a strip of tape. Group 2: acupressure wristbands applied to sham point on both arms before premedication. Immediately after induction of anaesthesia, wristbands were removed and acupuncture needles were applied to sham point on both arms, left in place until next day. Needles were secured with a strip of tape.
Outcomes	Vomiting (0–24h), risk of rescue antiemetic drug, side effects of acupressure/acupuncture.
Notes	Rescue antiemetic was ondansetron IV if two or more emetic episodes occurred. Combination of acupressure and acupuncture treatment effect was not analysed in subgroup analysis (invasive versus noninvasive). Proportion of acupuncture site redness and irritation was similar in both groups.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 100 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There were no differences between the groups with regard to demographics or previous retching, vomiting, or either (table 2)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“Postanesthesia care unit and ward nurses who assessed and charted postoperative emesis and medication administration were blinded to the group assignment of each patient”.
Blinding of outcome assessor? All outcomes	Yes	“Postanesthesia care unit and ward nurses who assessed and charted postoperative emesis and medication administration were blinded to the group assignment of each patient”.
Streitberger 2004
Methods	Acupuncturist obtained randomization allocation by phone from a member of the university clinical trials centre, who had no contact with study patients. Authors wrote ”an adequate allocation concealment was thereby assured“. Patients, outcome assessor, nurses, anaesthetists, and all other staff members were not informed about the allocation. Blinding of the patients was ensured by using a placebo needle that simulated an acupuncture procedure without penetrating the skin. Intention-to-treat analysis was used.
Participants	212 Females undergoing gynaecological or breast surgery under general anaesthesia. Exclusion: acupuncture treatment during the last 6 months, pregnancy, nausea or vomiting during the past 24 h, lymphoedema of the upper limbs, eczematous skin changes at the P6 acupoint, and coagulopathy. One patient in the acupuncture group withdrew consent and was treated as a failure in the analysis.
Interventions	Acupuncture group: 52 patients had acupuncture to P6 acupoint on both wrists, 20 min before induction of anaesthesia; another 54 patients had acupuncture to P6 acupoint on both wrists immediately after induction of anaesthesia. Sham acupuncture: 51 patients had placebo acupuncture to P6 acupoint on both wrists, 20 min before induction of anaesthesia; another 55 patients had placebo acupuncture to P6 acupoint on both wrists immediately after induction of anaesthesia.
Outcomes	Nausea (0–24h), vomiting (0–24h), risk of rescue antiemetic drugs, adverse events related to acupuncture.
Notes	Dimenhydinate and dolasetron rescue antiemetics used. Haematomas reported by one patient in the acupuncture group and by two patients in the placebo acupuncture group. Allergy to sticky plaster reported by 5 patients in each group. No severe adverse reaction reported.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	”The patients were randomly distributed by type of surgery (gynaecological or breast) to ensure balance between groups“. Comment: no further details provided in the paper.
Allocation concealment?	Yes	”The acupuncturist obtained randomisation allocation by phone from a member of the Coordination Centre for Clinical Trials, University of Heidelberg, who had no contact with study patients. An adequate concealment was thereby assured“.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals given. Intention-to-treat analysis used.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. ”Baseline characteristics revealed no relevant differences between the two groups (Table 1)“.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar. To assess blinding, patients were asked what kind of needle they believe they had received”.
Blinding of healthcare providers? All outcomes	Yes	“The patients, the observer of the endpoints, the nurses, the anaesthetists and all other staff members were not informed about the allocation”.
Blinding of outcome assessor? All outcomes	Yes	“The patients, the observer of the endpoints, the nurses, the anaesthetists and all other staff members were not informed about the allocation”.
Tavlan 1996
Methods	Method of allocation concealment not given. No details about blinding. This study was reported as an abstract.
Participants	65 Women (18–45 years) undergoing gynaecological laparoscopy.
Interventions	Group 1: ondansetron 8 mg IV before induction. Group 2: 0.2 ml 50% dextrose on the P6 acupoint before induction. Group 3: 20 ml IV saline before induction.
Outcomes	Nausea (0–1h), vomiting (0–1h).
Notes	Group 3 (n=20) not used in the acupoint P6 stimulation versus sham analyses.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 65 patients analysed.
Free of selective reporting?	Unclear	Risk of side effects and rescue antiemetic drugs not given because the article was an abstract.
Free of other bias?	Yes	Baseline characteristics were comparable. “No significant differences were observed between the groups in terms of demography”.
Blinding of patients? All outcomes	Unclear	Insufficient information.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Turgut 2007
Methods	Authors stated that patients were randomized using closed envelopes into one of two groups. In both groups, wristbands were covered by loose gauze to ensure observer-blinding. Anaesthesiologists caring for the patients were not aware of group assignment. Outcome assessor appears to be blinded to treatment allocation.
Participants	102 Women aged 40 to 65 years, with no previous experience of acupressure bands, undergoing elective gynaecological surgery (total abdominal hysterectomy and bilateral salpingo-oophorectomy). One patient in acupressure group and one in sham group withdrew because of swelling and erythema in treated hand and protocol violation respectively. Exclusion criteria: obesity (body mass index > 30), diabetes, history of motion sickness, postoperative nausea and vomiting, or smoking.
Interventions	Acupressure group: wristband with plastic bead positioned at P6 point on both wrists, 30 minutes before induction of general anaesthesia. Wristbands left on for 24 hours. Sham group: wristband with plastic bead positioned at non-acupoint site on the dorsal surface of both forearm, 30 minutes before induction of general anaesthesia. Wristbands left on for 24 hours. Both groups were educated on the use of patient controlled analgesia before surgery. Patients received patient controlled analgesia containing morphine in the postanaesthetic care room, and continued for 24 hours.
Outcomes	Nausea (0–24 h), vomiting (0– 24 h), rescue antiemetic drug use, adverse effects of wristbands.
Notes	Risks of nausea and vomiting on arrival in recovery room reported. No adverse effects or complications were observed due to acupressure wristbands, except for one patient in the acupressure group who withdrew due to swelling and erythema of the treated hand. Rescue antiemetic was metoclopramide 10 mg IV.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawal given. No missing data reported for 100 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	“Patients of both groups were comparable with regard to age, weight, height, ASA physical status and duration of surgery (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers? All outcomes	Yes	“The anaesthesiologists caring for the patients were not aware of group assignment”.
Blinding of outcome assessor? All outcomes	Yes	“The study was observer-blinded”.
Wang 2002
Methods	Yoking randomization procedure used. Children, parents, surgeons, anaesthetists, Recovery room nurses and research assistant were blinded to treatment groups. Small adhesive bandages applied to P6 acupoints on all subjects.
Participants	190 Children (7–16 years) undergoing general anaesthesia and outpatient surgical procedures. Exclusions: ASA physical status higher than II and subjects with a history of developmental delay or prematurity. Three children were excluded from study because of major study protocol violations.
Interventions	Group 1: after induction, intravenous saline was given. Acupuncture at P6 acupoints on both arms was performed before end of surgery. Injection of 0.2 mL of 50% dextrose using a B-D 1 mL tuberculin syringe with a 25-gauge needle at a depth of 5 to 7 mm from skin. Group 2: after induction, droperidol 10 ug/kg IV was given. Superficial skin prick at the P6 acupoint was performed before end of surgery. Group 3: after induction, intravenous saline was given. Sham point acupuncture at the dorsum of arms was performed before end of surgery. Injection of 0.2 mL of 50% dextrose using a B-D 1 mL tuberculin syringe with a 25-gauge needle at a depth of 5 to 7 mm from skin. Group 4: after induction, intravenous saline was given. Superficial skin prick at the P6 acupoint was performed before end of surgery.
Outcomes	Nausea (0-recovery room), vomiting (0-recovery room), risk of rescue antiemetic drug.
Notes	Rescue antiemetic was ondansetron IV 0.1–4 mg/kg. Group 3 and 4 were combined and considered as a sham group. No puncture site redness or irritation noted in any of the groups. Late outcomes (discharge to first day after surgery) also reported. No data on outcomes (0–24h) according to author.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	Yoking randomization (based on computer-generated list) was used to equal distribution of variables that are known to affect the outcome.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Details about withdrawals were given. No missing data reported for 187 children analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There were no differences among the various study groups in regard to baseline demographic characteristics such as age and history of PONV (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar. “Children, parents, surgeons, anesthesiologists, PACU nursing staff, and the research assistant, were all blinded to group assignment”.
Blinding of healthcare providers? All outcomes	Yes	“Children, parents, surgeons, anesthesiologists, PACU nursing staff, and the research assistant, were all blinded to group assignment”.
Blinding of outcome assessor? All outcomes	Yes	“Children, parents, surgeons, anesthesiologists, PACU nursing staff, and the research assistant, were all blinded to group assignment”.
White 2002
Methods	Randomization by computer-generated random number table. All patients were told that the ReliefBand acu-stimulation device produces a sensation which they may or may not feel to minimize bias. Patients recorded outcome measures in a patient diary.
Participants	120 Adults undergoing elective plastic surgery. Excluded: antiemetic medication within 24 hours before surgery, pregnancy, using permanent cardiac pacemaker, previous experience with acu-stimulation treatment, experiencing vomiting or retching within 24 hours before surgery. No patients withdrew before discharge from hospital, 5 patients withdrew from study at 72 hours follow up.
Interventions	Group 1: ondansetron 4 mg and inactive acu-stimulation device at P6 acupoint on arrival in the recovery room. Device worn for 72 hours after surgery. Group 2: saline 2 mL and active acu-stimulation device at P6 acupoint on arrival in the recovery room. Device worn for 72 hours after surgery. Group 3: ondansetron 4 mg and active acu-stimulation device at P6 acupoint on arrival in the recovery room. Device worn for 72 hours after surgery.
Outcomes	Nausea (0-hospital discharge), vomiting (0-hospital discharge), risk of rescue antiemetic drug, side effects.
Notes	Rescue antiemetic was metoclopramide 10 mg IV if persistent nausea or vomiting, or retching lasting more than 10 minutes. Group 3 data were not used for data analysis. No swelling at wrist or erythema reported. No outcome measures (0–72h) given in the paper.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Patients were randomly assigned to one of three treatment groups using a computer-generated random number table…”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data reported for 120 patients randomized.
Free of selective reporting?	Yes	All expected outcomes were reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “The three treatment groups were comparable with respect to demographic characteristics, pre-existing risk factors for development of PONV, and preoperative nausea scores (Table 1)”.
Blinding of patients? All outcomes	Yes	All patients were told that the ReliefBand acu-stimulation device produces a sensation which they may or may not feel to minimize bias. Patients recorded outcome measures in a patient diary.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Yes	All patients were told that the ReliefBand acu-stimulation device produces a sensation which they may or may not feel to minimize bias. Patients recorded outcome measures in a patient diary.
Yang 1993
Methods	Method of allocation concealment not given. Recovery room nurses collected data. No antiemetic drugs were given in the recovery room.
Participants	120 women undergoing gynaecological laparoscopy.
Interventions	Group 1: acupuncture group included patients given an injection of 0.2 mL 50%glucose in water into P6 acupoint before extubation. Group 2: antiemetic group was droperidol 20 ug/kg IV on induction of anaesthesia. Group 3: no treatment.
Outcomes	Vomiting (0–3h), side effects of acupuncture.
Notes	Reference group received no treatment and was not included in data analysis. Pain at acupoint site noted.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	No missing data recorded for 120 patients analysed.
Free of selective reporting?	No	Nausea was not reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “There was no statistically significant differences in age, weight, duration of anesthesia or amount of fluid given among the three groups of patients (Table 1)”.
Blinding of patients? All outcomes	Unclear	Insufficient information.
Blinding of healthcare providers? All outcomes	Unclear	Insufficient information.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Yentis 1992
Methods	Method of allocation concealment not given. Medical staff, children and parents were blinded to treatment groups. No specific details about who collected the outcomes and whether or not they were blinded to treatment allocation.
Participants	90 Children (1 to 16 years) undergoing strabismus surgery. One patient in each of the three groups could not be contacted after surgery.
Interventions	Group 1: acupuncture at P6 acupoint on right wrist with 5 minutes of manual stimulation after induction of anaesthesia. Group 2: antiemetic group had 0.075 mg/kg droperidol IV after induction of anaesthesia. Group 3: acupuncture (as in Group 1) and droperidol (as in Group 2) treatment.
Outcomes	Vomiting (0–48h), risk of rescue antiemetic drug, side effects of treatment.
Notes	Rescue antiemetic was dimenhydrinate IM. Restlessness more frequent in droperidol group than acupuncture group. Risk of vomiting before discharge from hospital also reported in paper. Group 3 data was not used in the data analysis.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Insufficient information.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	One patient in each group lost to follow up. Comment: unlikely to bias summary estimate.
Free of selective reporting?	Unclear	Nausea was not reported because it may have been difficult to assess in younger children.
Free of other bias?	Yes	Baseline characteristics were comparable. “Age, weight, number of muscles repaired and duration of anaesthesia did not differ among the groups (Table)”.
Blinding of patients? All outcomes	Yes	“Whether or not patients received droperidol, both treatments or acupuncture alone, was unknown to the staff, the patients and their parents”.
Blinding of healthcare providers? All outcomes	Yes	“Whether or not patients received droperidol, both treatments or acupuncture alone, was unknown to the staff, the patients and their parents”.
Blinding of outcome assessor? All outcomes	Unclear	Insufficient information.
Zarate 2001
Methods	Assignment of treatment by computer-generated random number table. All patients were told before the operation that the ReliefBand produces a sensation which they may or may not feel to minimize bias. Recovery room nurses were unaware of treatment groups.
Participants	250 Adults undergoing laparoscopic cholecystectomy. Excluded: patients who had taken antiemetic, glucocorticosteroids, or psychoactive medication within 24 hours before the operation; were pregnant; had an implanted cardiac pacemaker or defibrillator device; or had experienced vomiting or retching within 24 hours before surgery. 29 adults were excluded because of protocol violations.
Interventions	Group 1: ReliefBand (watch-like acu-stimulation device) positioned at P6 acupoint before the end of surgery. The device was set to deliver a 25 mA stimulus at 31 Hz. Patients wore the device for 9 hours after surgery. Group 2: ReliefBand with no acu-stimulation positioned at P6 acupoint before end of surgery, worn up to 9 hours after surgery. Group 3: ReliefBand with no acu-stimulation positioned at the dorsal aspect of the wrist before end of surgery, worn up to 9 hours after surgery.
Outcomes	Nausea (0-arrival in recovery room), vomiting (0-arrival in recovery room), risk of rescue antiemetic (0–2h), side effects of wristband. Rescue antiemetics were droperidol 0.625 mg IV and ondansetron 4 mg IV.
Notes	Group 2 and Group 3 were considered as the sham control group for data analysis. Although the ReliefBand devices were identical in appearance, their placement on the dorsal side of the wrist would have suggested that the patients were in Group 3. Outcomes also evaluated at 45,90,120,240,360 and 540 min after surgery. No cumulative data recorded (requested data from authors but no reply). Side effects of wristbands were mild cutaneous irritation with erythema.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	“Outpatients who had been fasted overnight were randomly assigned to one of three treatment groups (groups T, S, and P) with a computer-generated random number table”.
Allocation concealment?	Unclear	Insufficient information.
Incomplete outcome data addressed? All outcomes	Yes	Reasons for withdrawals were given. No missing data recorded for 221 patients analysed.
Free of selective reporting?	Yes	All expected outcomes reported.
Free of other bias?	Yes	Baseline characteristics were comparable. “The three treatment groups were comparable demographically and with respect to their histories of PONV and motion sickness, baseline nausea score, duration of surgery, and the time the acu-stimulation device was applied before the end of surgery (Table 1)”.
Blinding of patients? All outcomes	Yes	Authors took adequate steps to make interventions appear similar. “To minimize bias resulting from the presence or absence of the electrical stimulation, all patients were told before the operation that the ReliefBand produces a sensation which ’they might or might not feel”.
Blinding of healthcare providers? All outcomes	Yes	“The recovery room nursing staff were unaware of the acu-stimulation treatment group to which the patient had been assigned”.
Blinding of outcome assessor? All outcomes	Yes	“The recovery room nursing staff were unaware of the acu-stimulation treatment group to which the patient had been assigned”.