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Blood transfusion after percutaneous coronary intervention and risk of subsequent adverse outcomes: a systematic review and meta-analysis
Kwok CS, Sherwood MW, Watson SM, Nasir SB, Sperrin M, NolanJ, Kinnaird T, Kiatchoosakun S, Ludman PF, de Belder MA, et al
JACC: Cardiovascular Interventions. 2015;8((3):):436-46.
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Abstract
OBJECTIVES This study sought to define the prevalence and prognostic impact of blood transfusions in contemporary percutaneous coronary intervention (PCI) practice. BACKGROUND Although the presence of anemia is associated with adverse outcomes in patients undergoing PCI, the optimal use of blood products in patients undergoing PCI remains controversial. METHODS A search of EMBASE and MEDLINE was conducted to identify PCI studies that evaluated blood transfusions and their association with major adverse cardiac events (MACE) and mortality. Two independent reviewers screened the studies for inclusion, and data were extracted from relevant studies. Random effects meta-analysis was used to estimate the risk of adverse outcomes with blood transfusions. Statistical heterogeneity was assessed by considering the I(2) statistic. RESULTS Nineteen studies that included 2,258,711 patients with more than 54,000 transfusion events were identified (prevalence of blood transfusion 2.3%). Crude mortality rate was 6,435 of 50,979 (12.6%, 8 studies) in patients who received a blood transfusion and 27,061 of 2,266,111 (1.2%, 8 studies) in the remaining patients. Crude MACE rates were 17.4% (8,439 of 48,518) in patients who had a blood transfusion and 3.1% (68,062 of 2,212,730) in the remaining cohort. Meta-analysis demonstrated that blood transfusion was independently associated with an increase in mortality (odds ratio: 3.02, 95% confidence interval: 2.16 to 4.21, I(2) = 91%) and MACE (odds ratio: 3.15, 95% confidence interval: 2.59 to 3.82, I(2) = 81%). Similar observations were recorded in studies that adjusted for baseline hematocrit, anemia, and bleeding. CONCLUSIONS Blood transfusion is independently associated with increased risk of mortality and MACE events. Clinicians should minimize the risk for periprocedural transfusion by using available bleeding-avoidance strategies and avoiding liberal transfusion practices.Copyright 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Clinical Commentary
What is known?
Allogenic red cell transfusion is associated with adverse clinical outcomes in many clinical settings.
What did this paper set out to examine?
The authors conducted a systematic review of the evidence that relates to the relationship between red cell transfusion and adverse clinical outcomes in patients undergoing percutaneous coronary interventions (PCI). The study is timely because the increasingly elderly population referred for PCI are at increased risk of anaemia and acute haemorrhage, the two key indications for red cell transfusion.
What did they show?
The authors conducted a robust and well described systematic review of relevant databases. They identified 19 observational analyses that included 2,258,711 patients met their eligibility criteria; reporting of transfusions, death and Major Adverse Cardiac Events (MACE). The included studies were of mixed quality and showed differences in their design, definitions of primary and secondary exposures, duration of follow up, and type of analyses. Pooled effect estimates demonstrated strong associations between transfusion, mortality and MACE, although these analyses also demonstrated significant heterogeneity. Sub group analyses that included only studies with longer follow-up, or that contained adjustment for confounders such as transfusion volume or anaemia showed consistent associations between transfusion and harm, with some reduction in heterogeneity.
What are the implications for practice and for future work?
Implications for future research: The authors conclude that their data cannot demonstrate a causal relationship between transfusion and adverse outcomes in these patients. However they do discuss the possible pathological effects of transfusion and conclude that their data should support more restrictive transfusion practice. Implications for future practice: This study generates the hypothesis that reduced exposure to red cells may have benefits in these high risk patients. This hypothesis should be tested in a randomised controlled clinical trial. It is premature to suggest that the evidence presented here makes a case for restrictive practice.