Another Reason to Avoid Unnecessary Transfusions
Another Reason to Avoid Unnecessary Transfusions
Abstract & Commentary
By Saadia R. Akhtar, MD, MSc, Pulmonary and Critical Care Medicine, Yale University School of Medicine, is Associate Editor for Critical Care Alert
Professor, Pulmonary and Critical Care Medicine, Yale University School of Medicine
Dr. Akhtar does research for Eli Lilly.
Synopsis: This secondary analysis of a multicenter, prospective, observational study of ICU transfusion practices reveals that packed red blood cell transfusions are associated with an increased risk of blood stream infections.
Source: Shorr AF, et al. Transfusion practice and blood stream infections in critically ill patients. Chest. 2005; 127:1722-1728.
A growing body of literature describes an association between packed red blood cell (pRBC) transfusions and nosocomial infections.1,2 Shorr and colleagues set out to add to this by investigating the relationship between pRBC transfusions and bloodstream infections (BSI) in a large heterogeneous population of ICU patients. They performed a secondary analysis of a multicenter, prospective, observational cohort study (the CRIT trial)3 to compare pRBC transfusion rates in patients who acquired a BSI in the ICU to those who did not.
The presence of BSI was defined by positive blood culture. The original study was conducted from August 2000 to April 2001 at 284 US ICUs. Adult patients with anticipated ICU length of stay > 48 hours were eligible. Patients admitted to pediatric, cardiac, cardiothoracic and neurology ICUs were excluded. Patients were also excluded for renal failure on dialysis or if they were prohibited from receiving transfusions. For this secondary analysis, patients with BSI at or within 48 hours of admission to the ICU were excluded. Usual demographics, diagnoses, severity of illness scores, antibiotics given, presence of central line or parenteral nutrition and number of pRBC transfusions were recorded. Patients were followed for 30 days or until death or hospital discharge (if within 30 days). Standard statistical analyses were used.
Of the 4892 patients in the CRIT trial, 3502 patients were enrolled in the current study. (The remainder were excluded for early death or early ICU discharge, not otherwise defined, or early BSI as defined above.) Of 3502 enrolled patients, 117 (3.3%) developed BSI after a median of 11 days in the ICU. Univariate analysis revealed that patients who developed BSI were slightly younger. The presence of a central line and the use of cephalosporins were associated with BSI but receiving parenteral nutrition was not. Seventy six percent (76%) of patients with BSI received pRBC transfusions compared to 48.7% of those without BSI. Multivariate analysis identified use of cephalosporins, severity of illness on day 3-4, and pRBC transfusion as being independently associated with BSI. The odds ratio for BSI with pRBC transfusion was 2.23 (95% CI, 1.43-3.52), with a clear dose-response relationship.
Commentary
Shorr et al’s report reinforces our increasing appreciation of the fact that pRBC transfusions are not benign. There are apparent immunomodulatory and immunosuppressive effects of transfusions that may lead to significant infectious complications such as BSI. These finding are consistent with prior data.1,2
The study is limited in ways that most secondary analyses are limited: it is retrospective, and it may include biases and confounders not accounted for in the adjusted analyses. Shorr et al did not have information on the patients’ transfusion history prior to ICU admission, or on the transfusion of products other than pRBC. They also excluded about 25% of the original cohort for early death or early discharge from the ICU. BSI and/or transfusion in a portion of these latter patients could have markedly altered the results. Despite these problems, it is reassuring to note that the magnitude of the associations noted by Shorr et al correlate well with those reported in other studies. The presence of a dose-dependent response (that is, increased risk of BSI with increased numbers of pRBC transfusions) provides further support for the validity of their findings.
As we await prospective trials of transfusion practices designed to evaluate infection risk, I suggest that this preliminary but growing body of data combined with the evidence on safety of lower transfusion thresholds4 is enough for all of us to continue to work to change our practices and limit use of pRBC transfusions.
References
- Torchia MG, Danzinger RG. Perioperative blood transfusion and albumin administration are independent risk factors for the development of postoperative infections after colorectal surgery. Can J Surg. 2000;43: 212-216.
- Taylor RW, et al. Impact of allogeneic packed red blood cell transfusion on nosocomial infection rates in the critically ill. Crit Care Med. 2002;30:2246-2254.
- Corwin HL, et al. The CRIT Study: Anemia and blood transfusion in the critically ill-Current clinical practice in the United States. Crit Care Med. 2004; 32:39-52.
- Hebert PC, et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. N Engl J Med. 1999:340:409-417.
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