Comparison 1. Mortality at 30 days.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 30‐Day mortality	31	16729	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.86, 1.15]
1.2 30‐Day mortality subgroup by restrictive haemoglobin level	31	16729	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.86, 1.14]
1.2.1 Restrictive 7.0 g/dL to 7.5 g/dL	15	11572	Risk Ratio (M‐H, Random, 95% CI)	1.00 [0.83, 1.19]
1.2.2 Restrictive < 8.0 g/dL to 9.0 g/dL	16	5157	Risk Ratio (M‐H, Random, 95% CI)	0.97 [0.75, 1.24]
1.3 30‐Day mortality subgroup analysis by clinical specialties	31	16729	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.86, 1.14]
1.3.1 Cardiac surgery	4	7441	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.74, 1.33]
1.3.2 Orthopaedic surgery	8	3111	Risk Ratio (M‐H, Random, 95% CI)	1.16 [0.75, 1.79]
1.3.3 Vascular	2	157	Risk Ratio (M‐H, Random, 95% CI)	0.98 [0.30, 3.25]
1.3.4 Acute blood loss/trauma	3	1522	Risk Ratio (M‐H, Random, 95% CI)	0.65 [0.43, 0.97]
1.3.5 Critical care	9	3529	Risk Ratio (M‐H, Random, 95% CI)	1.06 [0.85, 1.32]
1.3.6 Acute myocardial infarction	3	820	Risk Ratio (M‐H, Random, 95% CI)	1.61 [0.38, 6.88]
1.3.7 Haematological malignancies	2	149	Risk Ratio (M‐H, Random, 95% CI)	0.37 [0.07, 1.95]
1.4 30‐Day mortality by clinical specialties: myocardial infarction vs all others	31	16729	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.86, 1.14]
1.4.1 Myocardial infarction	3	820	Risk Ratio (M‐H, Random, 95% CI)	1.61 [0.38, 6.88]
1.4.2 All but myocardial infarction	28	15909	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.86, 1.15]
1.5 Mortality by cardiac surgery, vascular surgery, myocardial infarction, and all others	31	16729	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.86, 1.14]
1.5.1 Cardiac surgery	4	7441	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.74, 1.33]
1.5.2 Myocardial infarction	3	820	Risk Ratio (M‐H, Random, 95% CI)	1.61 [0.38, 6.88]
1.5.3 Vascular surgery	2	157	Risk Ratio (M‐H, Random, 95% CI)	0.98 [0.30, 3.25]
1.5.4 Others	22	8311	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.83, 1.19]