Red blood cell transfusions and nosocomial infections in critically ill patients.

OBJECTIVE: A previous retrospective evaluation of Project Impact data demonstrated an association between red blood cell transfusions, nosocomial infections, and poorer outcomes in critically ill patients, independent of survival probability or patient age. The objective of this study was to determine whether transfused patients, independent of survival probability based on Mortality Prediction Model scores, have higher nosocomial infection rates, longer intensive care unit and hospital lengths of stay, and higher mortality rates than nontransfused patients. DESIGN: Prospective, observational, cohort study. SETTING: A single-center, mixed medical/surgical, closed intensive care unit. PATIENTS: : Adults admitted to St. John's Mercy Medical Center between August 2001 and June 2003 (n = 2,085) were enrolled using Project Impact software. Both nonoperative and postoperative populations were represented, and transfusion decisions were made independently of patient study inclusion. Patients whose nosocomial infection was diagnosed before transfusion were counted as nontransfused. INTERVENTIONS: : None. MEASUREMENTS AND MAIN RESULTS: Nosocomial infections, mortality rates, and intensive care unit and hospital length of stay were the main outcome measures. Of the 2,085 patients enrolled, 21.5% received red blood cell transfusions. The posttransfusion nosocomial infection rate was 14.3% in 428 evaluable patients, significantly higher than that observed in nontransfused patients (5.8%; p < .0001, chi-square). In a multivariate analysis controlling for patient age, maximum storage age of red blood cells, and number of red blood cell transfusions, only the number of transfusions was independently associated with nosocomial infection (odds ratio 1.097; 95% confidence interval 1.028-1.171; p = .005). When corrected for survival probability, the risk of nosocomial infection associated with red blood cell transfusions remained statistically significant (p < .0001). Leukoreduction tended to reduce the nosocomial infection rate but not significantly. Mortality and length of stay (intensive care unit and hospital) were significantly higher in transfused patients, even when corrected for illness severity. CONCLUSIONS: Red blood cell transfusions should be used sparingly, bearing in mind the potential risks of infection and poor outcomes in critically ill patients.

Impact of allogenic packed red blood cell transfusion on nosocomial infection rates in the critically ill patient.

OBJECTIVE: To determine whether critically ill patients who receive allogenic packed red blood cell transfusions are at increased risk of developing nosocomial infections during hospitalization. DESIGN: Retrospective database study utilizing Project IMPACT. SETTING: A 40-bed medical-surgical-trauma intensive care unit in an 825-bed tertiary referral teaching hospital. PATIENTS: One thousand seven hundred and seventeen patients admitted to the medical-surgical-trauma intensive care unit. MEASUREMENTS AND MAIN RESULTS: Data were collected by using the Project IMPACT database. Nosocomial infection rates were compared among three groups: the entire cohort, the transfusion group, and the nontransfusion group. We determined the nosocomial infection rates in these groups while adjusting for probability of survival by using Mortality Prediction Model (MPM-0) scores, age, gender, and number of units of packed red blood cells transfused. The average number of units transfused per patient was 4.0. The nosocomial infection rate for the entire cohort was 5.94%. The nosocomial infection rates for the transfusion group (n = 416) and the nontransfusion group (n = 1301) were 15.38% and 2.92%, respectively (p <.005 chi-square). Transfusion of packed red blood cells was related to the occurrence of nosocomial infection, and there was a dose-response pattern (the more units of packed red blood cells transfused, the greater the chance of nosocomial infection; p< 0.0001 chi-square). The transfusion group was six times more likely to develop nosocomial infection compared with the nontransfusion group. In addition, for each unit of packed red blood cells transfused, the odds of developing nosocomial infection were increased by a factor of 1.5. A subgroup analysis of nosocomial infection rates adjusted for probability of survival by using MPM-0 scores showed nosocomial infection to occur at consistently higher rates in transfused patients vs. nontransfused patients. A second subgroup analysis adjusted for patient age showed a statistically significant increase in rates of nosocomial infection for transfused patients regardless of age. CONCLUSIONS: Transfusion of packed red blood cells is associated with nosocomial infection. This association continues to exist when adjusted for probability of survival and age. In addition, mortality rates and length of intensive care unit and hospital stay are significantly increased in transfused patients.