Melling 2001.

Methods	Design: RCT Operative phase: preoperative Withdrawals: 4 Setting: 1 centre (UK) Sample size: 420 Funding: Smith & Nephew foundation; Augustine Medical inc
Participants	Age (range): not stated Gender (M/F): 174/242 ASA grade: not stated Surgery type: elective (mixed of clean surgery: breast, varicose veins, or hernia) Surgery duration: < 2 hrs (48/49.5 mins) Anaesthesia type: not stated/unclear
Interventions	Intervention (ABSW1): n = 139 "Systemic warming": forced‐air warming blanket Duration: 30 mins preoperative (the blanket was left on until just before surgery) (average: 38.73 min) Body area covered: whole body Proportion covered: not stated Intervention (ABSW2): n = 140 "Local warming": non‐contact radiant heat dressing, to just the planned wound area Duration 30 mins preoperative (average 44.94 mins Control: n = 141 Unwarmed cotton blankets (usual care) Duration: 30 mins (average: 38.73 mins) Control body area covered: not stated Proportion covered: wound treated only Co‐interventions: not stated Same standard preoperative care Room temperature: not stated
Outcomes	Wound infection Other outcomes reported not included in the review: Development of haematomas, seromas and/or wounds requiring aspiration Prescription of postoperative antibiotics ASEPSIS wound scores
Notes	Comparison 1 (x 2 comparisons) Comparison 2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Low risk	Opaque envelopes
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	A single trained observer unaware of treatment allocation reviewed participants at 2 and 6 weeks postoperatively
Baseline comparability of groups	Low risk	To a high degree according to Table 1
Co‐interventions equal between groups	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	2 participants in the control group and 1 in the local warming group were lost to follow‐up. 1 participant's surgery was cancelled
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