Comparison 2. Cell salvage ‐ blood transfused (washed versus unwashed).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 No. exposed to allogeneic blood (Cardiac)	31		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 Washed	13	1158	Risk Ratio (M‐H, Random, 95% CI)	0.66 [0.55, 0.80]
1.2 Unwashed	18	1360	Risk Ratio (M‐H, Random, 95% CI)	0.85 [0.76, 0.95]
2 No. exposed to allogeneic blood (Orthopaedic)	32		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1 Washed	10	800	Risk Ratio (M‐H, Random, 95% CI)	0.48 [0.36, 0.64]
2.2 Unwashed	22	2357	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.36, 0.63]
3 No. exposed to allogeneic blood (Vascular)	4		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
3.1 Washed	4	267	Risk Ratio (M‐H, Random, 95% CI)	0.63 [0.34, 1.15]