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.

Zilberberg and Shorr BMC Health Services Research 2007 7:138   doi:10.1186/1472-6963-7-138