Effect of a restrictive transfusion strategy on transfusion-attributable severe acute complications and costs in the US ICUs: a model simulation

Table 1 Analytic framework for the model*

	Model variable	Input	Source/Calculation
A	Total number of ICU admissions annually in the US	4.4 mil	VERICC [18]
B	% Adult ICU admissions	0.8	Groeger 1993 [19]
C	% At risk for a late TF	0.29	Corwin 2002 [16]
D	Mean # units/pt at risk – current practice	3.01	Corwin 2002 [16]
E	Mean # units/pt TF – restrictive strategy group	2.6	Corwin 2002 [16]
F	Number of patients in restrictive group	418	Hebert [15]
G	% Patients transfused in restrictive group	0.67	Hebert [15]
H	Mean # units/pt at risk – restrictive practice	1.74	(fxgxe)/f
I	Total annual number of units TF – current practice	3,073,360	Axbxcxd
j	Total annual number of units TF – restrictive practice	1,778,234	Axbxcxh
k	Total annual number of units TF avoided restrictive practice	1,295,126	i-j
l	CV+ARDS SACs in liberal group	136	Hebert 1999 [15]
m	CV+ARDS SACs in restrictive group	87	Hebert 1999 [15]
n	TSACs	49	l-m
o	Total pRBC u TF liberal	2,352	Hebert 1999 [15]^¶
p	Total pRBC u TF restrictive	728	Hebert 1999 [15]^¶
q	pRBC u TF excess	1,624	o-p
r	Units/1 TSAC	33	q/n
s	TSACs avoided restrictive practice	39,246	k/r

*ICU, intensive care unit; TF, transfusion; rHuEPO, recombinant human erythropoietin; CV, cardiovascular; ARDS, adult respiratory distress syndrome; SAC, severe acute complication; TSAC, transfusion-attributable severe acute complication; pRBC, packed red blood cells; u, unit ^¶The total number of units administered was calculated by multiplying the mean number of units transfused/patient by the number of patients transfused.

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