Comparison 4. Cell salvage ‐ blood transfused (active versus active).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 No. exposed to allogeneic blood (Active vs Active)	25		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 Cell Salvage (Active vs Active)	25	2402	Risk Ratio (M‐H, Random, 95% CI)	0.63 [0.53, 0.76]
2 No. exposed to allogeneic blood (Transfusion Protocol)	25		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1 Transfusion Protocol	19	1768	Risk Ratio (M‐H, Random, 95% CI)	0.64 [0.52, 0.77]
2.2 No Transfusion Protocol	6	634	Risk Ratio (M‐H, Random, 95% CI)	0.59 [0.35, 1.00]
3 No. exposed to allogeneic blood (Type of Surgery)	25		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
3.1 Cardiac	14	1304	Risk Ratio (M‐H, Random, 95% CI)	0.73 [0.61, 0.87]
3.2 Orthopaedic	11	1098	Risk Ratio (M‐H, Random, 95% CI)	0.46 [0.33, 0.65]
4 No. exposed to allogeneic blood (Washed vs Unwashed)	26		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
4.1 Washed	9	897	Risk Ratio (M‐H, Random, 95% CI)	0.61 [0.48, 0.78]
4.2 Unwashed	17	1543	Risk Ratio (M‐H, Random, 95% CI)	0.68 [0.52, 0.89]
5 No. exposed to allogeneic blood (Timing of cell salvage)	26		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
5.1 Intra‐operative cell salvage	4	281	Risk Ratio (M‐H, Random, 95% CI)	0.54 [0.35, 0.84]
5.2 Post‐operative cell salvage	18	1629	Risk Ratio (M‐H, Random, 95% CI)	0.65 [0.50, 0.85]
5.3 Intra & post‐operative cell salvage	4	530	Risk Ratio (M‐H, Random, 95% CI)	0.76 [0.59, 0.98]
6 Units of allogeneic blood transfused (Active vs Active)	8		Mean Difference (IV, Random, 95% CI)	Subtotals only
6.1 Cell Salvage (Active vs Active)	8	663	Mean Difference (IV, Random, 95% CI)	‐0.66 [‐1.02, ‐0.30]
7 Units of allogeneic blood transfused (Transfusion Protocol)	8		Mean Difference (IV, Random, 95% CI)	Subtotals only
7.1 Transfusion Protocol	7	561	Mean Difference (IV, Random, 95% CI)	‐0.67 [‐1.09, ‐0.25]
7.2 No Transfusion Protocol	1	102	Mean Difference (IV, Random, 95% CI)	‐0.69 [‐1.20, ‐0.18]
8 Units allogeneic blood transfused (Type of Surgery)	8		Mean Difference (IV, Random, 95% CI)	Subtotals only
8.1 Cardiac	6	501	Mean Difference (IV, Random, 95% CI)	‐0.39 [‐0.67, ‐0.12]
8.2 Orthopaedic	2	162	Mean Difference (IV, Random, 95% CI)	‐1.10 [‐1.91, ‐0.29]