Tanaka 2013.

Methods	Design: RCT Operative phase: intraoperative Withdrawals: 6 participants were excluded Setting: 1 centre (Japan) Sample size: 70 Funding: not reported
Participants	Age (mean): 55 ‐ 60 yrs Gender (M/F): 17/47 ASA grade: I ‐ III Surgery type: elective major abdominal surgery Surgery duration (mean): > 2 hrs ( 260/290 mins) Anaesthesia type: epidural and general
Interventions	Intervention (ABSW1): n = 33 Convective warming (Bair Hugger® system: Arizant Heatlhcare, Inc, USA) Temperature set at: 43ºC Duration: intraoperative Body area covered: upper body Intervention (ABSW2): n = 31 Resistive‐heating blanket (SmartCare®, Geratherm Medical AG, Germany) Temperature set at : 42ºC Duration: intraoperative Body area covered: upper body Co‐interventions: cotton blanket to sandwich the intervention. Room temperature (mean): 22° ‐ 24ºC
Outcomes	Blood loss (ml) Fluids infused (ml)
Notes	Comparison 2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization code
Allocation concealment (selection bias)	Low risk	Opaque, sealed and sequentially‐numbered envelopes
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Open‐label ('risk of bias' judgement depending on the nature of the outcome)
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Open‐label ('risk of bias' judgement depending on the nature of the outcome)
Baseline comparability of groups	Low risk	To a high extent according to Table 1
Co‐interventions equal between groups	Unclear risk	No details are provided
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	6 participants were excluded (2 and 4), and reasons given in Fig. 1
Selective reporting (reporting bias)	Unclear risk	We did not have access to the protocol, therefore we cannot exclude risk of selective reporting with the information provided
Other bias	Low risk