A clinical prediction tool to estimate the number of units of red blood cells needed in primary elective coronary artery bypass surgery.
BACKGROUND
Red blood cell (RBC) transfusion is common during cardiac surgical procedures. Empiric crossmatching, without attempting to estimate individual transfusion requirements is typical. We hypothesized that a clinical prediction tool could be developed to estimate the number of units of RBCs needed for coronary artery bypass grafting (CABG) surgery.


METHODS
With institutional review board approval, detailed demographic, risk factor, and transfusion data of primary elective CABG procedures (n=5887) from September 1, 1993, to June 20, 2002, were studied and the data set was divided into development and validation subgroups. Multivariable ordinal logistic regression was used to develop and validate transfusion risk factors, assign them a relative weight, and create a model to stratify patients into groups depending on predicted need for 0, 2, 4, or more than 4 RBC units. The model was compared with current standard practice of crossmatching 4 RBC units in terms of observed blood product usage over the study period.


RESULTS
Demographic and transfusion risk factor variables in the development (n=3876) and validation (n=2011) data sets were similar. The predictive value of the model was good for the development and validation groups, with a c-index of 0.79 and 0.78, respectively. Applying the predictive model reduced the number of crossmatches by 30% without underproviding RBC units and increased the percentage of patients crossmatched exactly for the required number of units from 11% to 21%.


CONCLUSIONS
Predictive factors for RBC transfusion were identified and used to construct a clinical tool to conserve blood bank resources without increasing patient risk.
Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA.
Ian
I
Welsby
Jennifer
J
Crow
Nicholas
N
Bandarenko
George
G
Lappas
Barbara
B
Phillips-Bute
Mark
M
Stafford-Smith
D001771:Blood Banks / Q000706:statistics & numerical data; D016063:Blood Loss, Surgical / Q000706:statistics & numerical data*; D001026:Coronary Artery Bypass / Q000379:methods* / Q000706:statistics & numerical data; D016208:Databases, Factual; D004502:Education, Medical, Continuing; D017558:Elective Surgical Procedures / Q000379:methods* / Q000706:statistics & numerical data; D017707:Erythrocyte Transfusion / Q000706:statistics & numerical data*; D006801:Humans; D015233:Models, Statistical; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012307:Risk Factors