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Table 1 Analytic framework for the model*

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

  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
  1. *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.