Benson 2012.

Methods	Design: RCT Operative phase: pre‐ and intraoperative Withdrawals: 1 (not informed) Setting: 1 centre (Canada) Sample size: 30 Funding: grant from the Fort Garry Branch Royal Canadian Legion Poppy
Participants	Age (mean): 68.0/68.5 years Gender (M/F): 12/18 ASA grade: I ‐ III Surgery type: elective (total knee arthroplasty) Surgery duration (mean): < 2 hrs (60.1/61.9 mins anaesthesia duration) Anaesthesia type: spinal
Interventions	Intervention (ABSW): n = 15 Forced‐air warming gown connected to a portable warming unit capable of generating up to 1000 BTU per hr (Bair Paws® patient adjustable Warming System, Arizant HealthCare, Eden Prairie, MN. Gown model 81001, unit model 875) Temperature (max.) at 43ºC Duration: perioperative Body area covered: not stated Control: n = 15 Hospital gown and prewarmed standard cotton blanket Duration: perioperative Control body area covered: spread over the trunk, upper limbs and head * Note: Each group retained the same warming method throughout the perioperative period (defined here as from the time of preoperative preparation in the day surgery through to discharge from the PACU) Co‐interventions: not stated Room temperature: 20.5ºC
Outcomes	Postoperative pain (at 12 and 24 hours) (VNRS 0 ‐ 10) Thermal comfort (Likert 1 ‐ 5) Other outcomes reported not included in the review: Participants with a pain score ≥ 4 "adequate management of pain" Use of opioids % Participants that became hypothermic
Notes	Comparison 1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Lot drawing with coloured papers in a bag
Allocation concealment (selection bias)	High risk	There was no allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open‐label
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome assessment was done at PACU, but there is no mention of blinding
Baseline comparability of groups	Low risk	To a high extent according to Table 1
Co‐interventions equal between groups	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	High risk	There are several outcomes with incomplete outcome data
Selective reporting (reporting bias)	Unclear risk	We did not have access to the protocol, therefore we cannot exclude risk of selective reporting.
Other bias	Low risk