Comparison 5. Active vs no active (subgroup analysis by anaesthesia type).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Surgical site infection and complications	2	479	Risk Ratio (M‐H, Random, 95% CI)	0.36 [0.20, 0.66]
1.1 General	1	200	Risk Ratio (M‐H, Random, 95% CI)	0.31 [0.13, 0.74]
1.2 Not stated	1	279	Risk Ratio (M‐H, Random, 95% CI)	0.42 [0.19, 0.92]
2 Major cardiovascular complications (cardiovascular death, non‐fatal myocardial infarction, non‐fatal stroke, and non‐fatal cardiac arrest)	1	300	Risk Ratio (M‐H, Random, 95% CI)	0.22 [0.05, 1.00]
3 Non‐fatal myocardial infarction	1	300	Risk Ratio (M‐H, Random, 95% CI)	0.37 [0.02, 9.03]
4 Non‐fatal cardiac arrest	1	300	Risk Ratio (M‐H, Random, 95% CI)	0.22 [0.05, 1.00]
5 Blood transfusions during surgery and up to 48 hours post‐surgery (mL)	5	404	Mean Difference (IV, Random, 95% CI)	‐35.82 [‐82.87, 11.23]
5.1 General	4	354	Mean Difference (IV, Random, 95% CI)	‐37.35 [‐88.35, 13.66]
5.2 Spinal	1	50	Mean Difference (IV, Random, 95% CI)	‐25.0 [‐240.82, 190.82]
6 Participants transfused	6	465	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.56, 1.42]
6.1 General	5	415	Risk Ratio (M‐H, Random, 95% CI)	0.80 [0.44, 1.46]
6.2 Spinal	1	50	Risk Ratio (M‐H, Random, 95% CI)	1.15 [0.70, 1.89]
7 Blood loss during surgery ‐ mL	16	963	Mean Difference (IV, Random, 95% CI)	‐57.02 [‐97.69, ‐16.35]
7.1 General	9	448	Mean Difference (IV, Random, 95% CI)	‐80.71 [‐147.89, ‐13.53]
7.2 Spinal	4	160	Mean Difference (IV, Random, 95% CI)	34.34 [‐22.95, 91.63]
7.3 Combined	2	325	Mean Difference (IV, Random, 95% CI)	‐129.95 [‐144.78, ‐115.11]
7.4 Unknown	1	30	Mean Difference (IV, Random, 95% CI)	‐56.0 [‐160.52, 48.52]
8 Fluids transfused during surgery ‐ mL	17	1079	Mean Difference (IV, Random, 95% CI)	‐178.22 [‐275.00, ‐79.44]
8.1 General	11	589	Mean Difference (IV, Random, 95% CI)	‐201.50 [‐364.99, ‐38.01]
8.2 Spinal	4	160	Mean Difference (IV, Random, 95% CI)	‐43.94 [‐187.94, 100.07]
8.3 Combined	1	300	Mean Difference (IV, Random, 95% CI)	‐198.00 [‐237.37, ‐162.63]
8.4 Unknown	1	30	Mean Difference (IV, Random, 95% CI)	‐448.0 [‐701.78, ‐194.22]
9 Participant's anxiety and state	1	130	Mean Difference (IV, Random, 95% CI)	0.40 [‐0.57, 1.37]
10 Participant's comfort (thermal) (higher values mean higher comfort)	10	700	Std. Mean Difference (IV, Random, 95% CI)	0.77 [0.19, 1.36]
10.1 General	4	431	Std. Mean Difference (IV, Random, 95% CI)	0.92 [‐0.18, 2.01]
10.2 Spinal	4	110	Std. Mean Difference (IV, Random, 95% CI)	0.68 [‐0.32, 1.69]
10.3 Combined	1	29	Std. Mean Difference (IV, Random, 95% CI)	0.78 [0.02, 1.54]
10.4 Unknown	1	130	Std. Mean Difference (IV, Random, 95% CI)	0.46 [0.11, 0.81]
11 Pain	5	214	Mean Difference (IV, Random, 95% CI)	0.06 [‐0.71, 0.82]
11.1 General	2	126	Mean Difference (IV, Random, 95% CI)	‐0.06 [‐0.51, 0.39]
11.2 Spinal	2	59	Mean Difference (IV, Random, 95% CI)	0.05 [‐2.01, 2.11]
11.3 Combined	1	29	Mean Difference (IV, Random, 95% CI)	1.0 [‐1.35, 3.35]
12 Chills/shivering	25	1466	Risk Ratio (M‐H, Random, 95% CI)	0.36 [0.25, 0.53]
12.1 General	15	584	Risk Ratio (M‐H, Random, 95% CI)	0.28 [0.17, 0.48]
12.2 Spinal	7	523	Risk Ratio (M‐H, Random, 95% CI)	0.56 [0.33, 0.96]
12.3 Combined	2	329	Risk Ratio (M‐H, Random, 95% CI)	0.25 [0.13, 0.48]
12.4 Unknown	1	30	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
13 All cause mortality	2	500	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.26, 4.00]
13.1 General	1	200	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.13, 6.42]
13.2 Spinal	1	300	Risk Ratio (M‐H, Random, 95% CI)	1.11 [0.16, 7.80]