title: Length of red cell unit storage and risk for delirium after cardiac surgery.
abstract: BACKGROUND
  The time that red cell units are stored before transfusion may be associated with postoperative complications, although the evidence is conflicting. However, the association between the length of red cell unit storage and postoperative delirium has not been explored. We hypothesized that the length of storage of transfused red cell units would be associated with delirium after cardiac surgery.
  
  
  METHODS
  We conducted a case-control study in which patients undergoing coronary artery bypass, valve, or ascending aorta surgery with cardiopulmonary bypass at Johns Hopkins from 2005 to 2011 were eligible for inclusion. Patients were excluded if they did not receive red cell units, received >4 red cell units during hospitalization, received any transfusion after the first postoperative day, or received red cell units that were not exclusively stored for ≤14 days or >14 days. Eighty-seven patients met transfusion-related inclusion criteria and developed postoperative delirium. Controls who did not develop delirium were selected from the same source population of eligible patients and were matched 1:1 based on age (± 5 years), 2- to 2.5-year band of date of surgery, and surgical procedure. For each patient, we calculated the average storage duration of all transfused red cell units. The primary outcome was odds of delirium in patients who were transfused red cell units with exclusive storage duration >14 days compared with that of ≤14 days. Secondary outcomes were odds of delirium with each increasing day of average red cell unit storage duration. We used conditional multivariable regression to test our hypotheses.
  
  
  RESULTS
  In conditional multivariable analysis of 87 case-control pairs, there was no difference in the odds of patients developing delirium if they were transfused red cell units with an exclusive storage age >14 days compared with that ≤14 days (odds ratio [OR] 1.83; 95% confidence interval, 0.73-4.58, P = 0.20). Each additional day of average red cell unit storage beyond 14 days was associated with a 1.01- to 1.13-fold increase in the odds of postoperative delirium (OR, 1.07; P = 0.03). Each additional day of average storage beyond 21 days was associated with a 1.02- to 1.23-fold increase in the odds of postoperative delirium (OR, 1.12; P = 0.02).
  
  
  CONCLUSIONS
  Transfusion of red cell units that have been stored for >14 days is not associated with increased odds of delirium. However, each additional day of storage >14 or 21 days may be associated with increased odds of postoperative delirium in patients undergoing cardiac surgery. More research is needed to further characterize the association between delirium and storage duration of transfused red cell units.
authors.affiliation: From the Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Brown
authors.forename: Maura
authors.initials: M
authors.lastname: Grega
authors.forename: Ola A
authors.initials: OA
authors.lastname: Selnes
authors.forename: Guy M
authors.initials: GM
authors.lastname: McKhann
authors.forename: Ashish S
authors.initials: AS
authors.lastname: Shah
authors.forename: Andrew
authors.initials: A
authors.lastname: LaFlam
authors.forename: William J
authors.initials: WJ
authors.lastname: Savage
authors.forename: Steven M
authors.initials: SM
authors.lastname: Frank
authors.forename: Charles W
authors.initials: CW
authors.lastname: Hogue
authors.forename: Rebecca F
authors.initials: RF
authors.lastname: Gottesman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015142:Baltimore; D001771:Blood Banks; D001793:Blood Preservation / Q000009:adverse effects*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D001026:Coronary Artery Bypass / Q000009:adverse effects; D003693:Delirium / Q000175:diagnosis / Q000209:etiology* / Q000523:psychology; D017707:Erythrocyte Transfusion / Q000009:adverse effects*; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D019106:Postoperative Hemorrhage / Q000209:etiology / Q000628:therapy*; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects*