title: A random forest based risk model for reliable and accurate prediction of receipt of transfusion in patients undergoing percutaneous coronary intervention.
abstract: BACKGROUND
  Transfusion is a common complication of Percutaneous Coronary Intervention (PCI) and is associated with adverse short and long term outcomes. There is no risk model for identifying patients most likely to receive transfusion after PCI. The objective of our study was to develop and validate a tool for predicting receipt of blood transfusion in patients undergoing contemporary PCI.
  
  
  METHODS
  Random forest models were developed utilizing 45 pre-procedural clinical and laboratory variables to estimate the receipt of transfusion in patients undergoing PCI. The most influential variables were selected for inclusion in an abbreviated model. Model performance estimating transfusion was evaluated in an independent validation dataset using area under the ROC curve (AUC), with net reclassification improvement (NRI) used to compare full and reduced model prediction after grouping in low, intermediate, and high risk categories. The impact of procedural anticoagulation on observed versus predicted transfusion rates were assessed for the different risk categories.
  
  
  RESULTS
  Our study cohort was comprised of 103,294 PCI procedures performed at 46 hospitals between July 2009 through December 2012 in Michigan of which 72,328 (70%) were randomly selected for training the models, and 30,966 (30%) for validation. The models demonstrated excellent calibration and discrimination (AUC: full model  = 0.888 (95% CI 0.877-0.899), reduced model AUC = 0.880 (95% CI, 0.868-0.892), p for difference 0.003, NRI = 2.77%, p = 0.007). Procedural anticoagulation and radial access significantly influenced transfusion rates in the intermediate and high risk patients but no clinically relevant impact was noted in low risk patients, who made up 70% of the total cohort.
  
  
  CONCLUSIONS
  The risk of transfusion among patients undergoing PCI can be reliably calculated using a novel easy to use computational tool (https://bmc2.org/calculators/transfusion). This risk prediction algorithm may prove useful for both bed side clinical decision making and risk adjustment for assessment of quality.
authors.affiliation: Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Hitinder S
authors.initials: HS
authors.lastname: Gurm
authors.affiliation: Department of Thrombosis and Hemostasis and Department of Nephrology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Judith
authors.initials: J
authors.lastname: Kooiman
authors.affiliation: Department of Internal Medicine, St John Providence Health System, Detroit, Michigan, United States of America.
authors.forename: Thomas
authors.initials: T
authors.lastname: LaLonde
authors.affiliation: Department of Internal Medicine, Detroit Medical Center, Detroit, Michigan, United States of America.
authors.forename: Cindy
authors.initials: C
authors.lastname: Grines
authors.affiliation: Blue Cross Blue Shield of Michigan, Detroit, Michigan, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Share
authors.affiliation: Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Milan
authors.initials: M
authors.lastname: Seth
mesh_terms: D000368:Aged; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D017063:Outcome Assessment, Health Care / Q000379:methods; D062645:Percutaneous Coronary Intervention / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors