Ng 2006.

Methods	Design: RCT Operative phase: intraoperative Withdrawals: None Setting: multicentre (Hong Kong) Sample size: 60 Funding: not stated
Participants	Age (mean): 67.4 years Gender (M/F): 17/43 ASA grade: I ‐ III Surgery type: elective (total knee replacement) Surgery duration: < 2 hrs (90 mins) Anaesthesia type: spinal‐epidural
Interventions	Intervention (ABSW1): n = 30 Upper‐body forced‐air warming (Bair Hugger®, Augustine Medical, Inc., Eden Prairie, MN) + a cotton blanket was folded once to make 2 layers in thickness, with the forced‐air warming blanket sandwiched between the 2 layers Duration: after induction until end of surgery Temperature setting at 43°C Body area covered: not stated Intervention (ABSW2): n = 30 Electric heating pads (Operatherm 20+ prewarmed gel) Duration: not stated Temperature setting at 39°C Body area covered: not stated Co‐interventions: all IV fluids were warmed to 37ºC with an infusion warmer (BW 485 l, Biegler GmbH, Austria) Room temperature: 20° ± 1ºC
Outcomes	Thermal comfort in post‐surgical waking‐up (VAS 0 ‐ 10) Shivering (present/absent) Blood loss (ml) Fluids infused (crystalloids) (ml)
Notes	Comparison 2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	High risk	The study was not blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	The study was not blinded
Baseline comparability of groups	Low risk	To a high extent according to Table 1
Co‐interventions equal between groups	Low risk	Yes
Incomplete outcome data (attrition bias) All outcomes	Low risk	All randomized participants were analysed
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