Table 4.

Relative risk (old vs. fresh blood) of composite morbidity^* based on average storage duration of RBC units transfused

	21-day cutoff		28-day cutoff		35-day cutoff		Mean Storage Duration (No Cutoff)
	RR (95% CI)	p- value	RR (95% CI)	p- value	RR (95% CI)	p- value	RR (95% CI)	p-value
Age	0.99 (0.97– 1.02)	0.7	0.99 (0.97– 1.03)	0.99	0.99 (0.96– 1.03)	0.7	0.995 (0.97– 1.02)	0.7
Gender
- Female	Reference		Reference		Reference		Reference
- Male	1.42 (0.71– 2.83)	0.3	1.49 (0.77– 2.90)	0.2	1.48 (0.72– 3.05)	0.3	1.46 (0.75– 2.84)	0.3
Mean units of blood transfused	1.07 (0.997– 1.15)	0.06	1.07 (1.006– 1.15)	0.03	1.13 (1.05– 1.20)	0.1	1.10 (1.02– 1.17)	0.008
MSDRGWt	1.30 (1.14– 1.49)	<0.001	1.25 (1.15– 1.36)	<0.001	1.21 (1.12– 1.31)	<0.001	1.26 (1.15– 1.38)	<0.001
BMI	1.07 (1.01– 1.12)	0.01	1.07 (1.01– 1.12)	0.045	1.05 (1.01– 1.11)	0.02	1.06 (1.01– 1.11)	0.01
Average Storage Duration - <21 days - ≥21 days - <28 days - ≥28 days - <35 days - ≥35 days - Continuous variable (per day)	Reference 4.48 (0.68– 29.59)	0.1	Reference 2.54 (1.31– 4.95)	0.006	Reference 3.35 (1.95– 5.77)	<0.001	1.08 (1.01– 1.15)	0.02

^*Composite morbidity defined as any of the following: (1) infection, (2) thrombotic event, (3) renal event, (4) respiratory event, (5) ischemic event.

MSDRGWt- casemix index

BMI- body mass index