title: Red Blood Cell Transfusions Impact Pneumonia Rates After Coronary Artery Bypass Grafting.
abstract: BACKGROUND
  Pneumonia, a known complication of coronary artery bypass grafting (CABG), significantly increases a patient's risk of morbidity and mortality. Although not well characterized, red blood cell (RBC) transfusions may increase a patient's risk of pneumonia. We describe the relationship between RBC transfusion and postoperative pneumonia after CABG.
  
  
  METHODS
  A total of 16,182 consecutive patients underwent isolated CABG between 2011 and 2013 at 1 of 33 hospitals in the state of Michigan. We used multivariable logistic regression to estimate the relative odds of pneumonia associated with the use or number of RBC units (0, 1, 2, 3, 4, 5, and ≥ 6). We adjusted for predicted risk of mortality, preoperative hematocrit values, history of pneumonia, cardiopulmonary bypass duration, and medical center. We confirmed the strength and direction of these relationships among selected clinical subgroups in a secondary analysis.
  
  
  RESULTS
  Five hundred seventy-six (3.6%) patients had pneumonia and 6,451 (39.9%) received RBC transfusions. There was a significant association between any RBC transfusion and pneumonia (adjusted odds ratio [ORadj], 3.4; p < 0.001). There was a dose response between number of units and odds of pneumonia, with a ptrend less than 0.001. Patients receiving only 2 units of RBCs had a 2-fold (ORadj, 2.1; p < 0.001) increased odds of developing pneumonia. These findings were consistent across clinical subgroups.
  
  
  CONCLUSIONS
  We found a significant volume-dependent association between an increasing number of RBCs and the odds of pneumonia, which persisted after risk adjustment. Clinical teams should explore opportunities for preventing a patient's risk of RBC transfusions, including reducing hemodilution or adopting a lower transfusion threshold in a stable patient.
authors.affiliation: Department of Cardiac Surgery, University of Michigan, Ann Arbor, Michigan; Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative. Electronic address: likosky@umich.edu.
authors.forename: Donald S
authors.initials: DS
authors.lastname: Likosky
authors.affiliation: Division of Cardiac Surgery, Henry Ford Hospital, Detroit, Michigan.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Paone
authors.affiliation: Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Mary A M
authors.initials: MA
authors.lastname: Rogers
authors.affiliation: Heart and Vascular Institute, Henry Ford Macomb Hospitals, Clinton Township, Michigan.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Harrington
authors.affiliation: Department of Cardiac Surgery, University of Michigan, Ann Arbor, Michigan; Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative.
authors.forename: Patricia F
authors.initials: PF
authors.lastname: Theurer
authors.affiliation: Department of Cardiac Surgery, Bronson Methodist Hospital, Kalamazoo, Michigan.
authors.forename: Alphonse
authors.initials: A
authors.lastname: DeLucia
authors.affiliation: Department of Cardiac Surgery, University of Michigan, Ann Arbor, Michigan; Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative.
authors.forename: Astrid
authors.initials: A
authors.lastname: Fishstrom
authors.affiliation: School of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Anton
authors.initials: A
authors.lastname: Camaj
authors.affiliation: Department of Cardiac Surgery, University of Michigan, Ann Arbor, Michigan; Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Prager
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001026:Coronary Artery Bypass; D017707:Erythrocyte Transfusion / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000453:epidemiology* / Q000209:etiology*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology*; D011446:Prospective Studies