Table II.

Transfusion data of two series of patients undergoing surgery for total knee arthroplasty, managed with (reinfusion group) or without (control group) postoperative reinfusion of unwashed shed blood.

	Control group	Reinfusion group	p	Effect size Cohen's d
All patients (n, %)	330 (100)	763 (100)
Pre-operative Hb (g/dL)	13.6±1.2	13.5±1.2	0.233	0.08
ARCT index (units/patient)	0.54±1.01	0.18±0.61	0.001	0.43
PSBT index (units/patient)	0	0.57±0.52	0.001	1.55
Overall index (units/patient)	0.54±1.01	0.75±0.75	0.001	0.24
Difference (units/patient)	0.21 (95% CI, 0.11–0.32)
Patients with ARCT (n, %)	81 (24.5)	65 (8.5)	0.001
Pre-operative Hb (g/dL)	13.0±1.4	12.5±1.2	0.042	0.38
ARCT index (units/patient)	2.19±0.71	2.06±0.61	0.260	0.20
PSBT index (units/patient)	0	0.35±0.51	0.001	0.97
Overall index (units/patient)	2.19±0.71	2.41±0.77	0.062	0.30
Difference (units/patient)	0.23 (95% CI, −0.01–0.47)
Patients without ARCT n (%)	249 (75.5)	698 (91.5)	0.001
Pre-operative Hb (g/dL)	13.9±1.1	13.6±1.4	0.008	0.24
PSBT index (units/patient)	0	0.59±0.52	0.001	1.60
Overall index (units/patient)	0	0.59±0.52	0.001	1.60
Difference (units/patient)	0.59 (95% CI, 0.53–0.66)

Legend ARCT: allogeneic red cell transfusion; Hb: haemoglobin; PSBT: post-operative salvaged blood transfusion. Data are expressed as mean ± SD or n. and % of total patients. p for reinfusion group vs control group.