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Is Fresh Blood Really Necessary: What is the Latest?

Is Fresh Blood Really Necessary: What is the Latest?. Sarah Harm, MD Department of Pathology University of Pittsburgh Medical Center Institute for Transfusion Medicine. en.wikitravel.org. Retrospective or observational studies. Retrospective Studies. Positives Easier to get IRB approval

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Is Fresh Blood Really Necessary: What is the Latest?

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  1. Is Fresh Blood Really Necessary: What is the Latest? Sarah Harm, MD Department of Pathology University of Pittsburgh Medical Center Institute for Transfusion Medicine en.wikitravel.org

  2. Retrospective or observational studies

  3. Retrospective Studies • Positives • Easier to get IRB approval • Data already exists & patient consent not required • Good for generating hypotheses • Negatives • Not randomized: opportunity for confounding/bias • Must ensure demographics of patient groups are well-matched • Often require complicated statistics to show result

  4. Confounding by indication • # RBCs transfused is highly correlated to age of RBCs • Sicker patients receive more RBC transfusions • Thus sicker patients tend to get older RBCs • Sicker patients have worse outcomes • So is an unfavorable outcome due to the patients’ natural history or receipt of older RBCs? ?

  5. Large, retrospective study on age of RBCs in cardiac surgery patients • CABG or valve surgery patients • RBC age: ≤ 14 days vs. >14 days • Patients who received a mix of “fresher” and “older” blood were excluded • Composite endpoint: Koch et al. NEJM 2008

  6. Both groups of patients received median 2 RBC units • 2872 patients in Newer blood group • Median RBC age:11days old • 3130 patients in Older blood group • Median RBC age:20days old 50% Koch et al. NEJM 2008

  7. Worse outcomes amongst massive transfusion recipients Koch et al. Crit Care Med 2006

  8. Matching of cohorts was not perfect Koch et al. NEJM 2008

  9. Better outcomes in group O coronary angiography patients Carpeggiani et al. Atherosclerosis 2010

  10. Outcome measures were broad and not easily explained by RBC transfusion Koch et al. NEJM 2008

  11. Greater mortality amongst recipients of median 2 RBC units 92.6% 92.6% Worse LV dysfunction More MV regurgitation 89.0% (p<0.001) More peripheral vascular dz Koch et al. NEJM 2008

  12. Conclusions • Mortality end points are very broad • Actual causes of death not presented • Death caused by being run over by abusafter receiving RBCs would appear as related to the transfusion • Authors offer no specific mechanism linking “older” blood to negative outcomes • Authors do not propose changing the current RBC issuing practice • Large study, hypothesis generator

  13. Relationship between # RBC transfused and ICU/Hosp LOS Hospital LOS RBCs transfused Days / number of RBCs ICU LOS 1-7 8-14 15-21 22-28 29-35 36-42 Length of storage of oldest RBC Vamvakas et al., Transfusion 2000

  14. Another retrospective study of mortality and storage lesion • The largest retrospective study to date • Analyzed database containing Swedish and Danish transfusion recipients from 1995-2002 • Inclusion criteria: • Ages 15 – 90 • No tx 2 years prior to index transfusion • Exclusion criteria: • Receipt of autologous RBCs • Receipt of ABO non-identical units • Receipt of RBCs of unknown ABO group/age Edgren G et al. Transfusion 2010

  15. Another retrospective study of mortality and storage lesion • Patients were generally surgery or trauma patients • Divided into 5 groups based on RBC age • 0-9 days old • 10-19 days old • 20-29 days old • 30-42 days old • Mixed • The reference group of recipients was the 10-19 day old RBC group Edgren G et al. Transfusion 2010

  16. Survival assessed over 2 periods • Short term survival (404,959tx, 387,130 patients): • Transfused on day 1 and followed for 7 days • Long term survival (380,549tx, 364,037 patients): • Transfused between days 1-7 and followed from day 8 through 2 years • Surveillance also terminated upon death, emigration and end of study period (31 Dec 2002) Edgren G et al. Transfusion 2010

  17. Patient demographics • The recipients were well matched between groups • Matched for age, gender, ABO, hospital LOS, number of RBCs, indications for transfusion • Median storage ages: • 0-9 days:7(5-8) • 10-19 days:14 (12-16) • 20-29 days:23(21-26) • 30-42 days:34(31-37) • Mixed:17(11-22) Edgren G et al. Transfusion 2010

  18. Mortality outcomes • Mortality not increased amongst recipients of oldest RBCs who were ≥70 years, or CABG, or ECMO • Leukoreduction did not affect survival Edgren G et al. Transfusion 2010

  19. Causes of mortality • Compared recipients of 30-42 days old to 10-19 days old • No single cause of death predominated Day 1-7 Day 8-730 Edgren G et al. Transfusion 2010

  20. Chicken and egg… • The number of 30-42 day old units received did not influence mortality ? Edgren G et al. Transfusion 2010; Middelburg RA et al. Transfusion 2010

  21. Another retrospective study of mortality and storage lesion • The largest, by far, study to date • Well matched patient demographics • Was the 5% increase in mortality causally related to RBC transfusion? • 5% increase in mortality surprisingly stable over time • No single cause of death predominated • No dose response relationship • How to explain the result in the mixed group? • Seems related to underlying disease, not RBC

  22. Conclusions on non-randomized studies • Hypothesis generating • Major limitation: • Lack of randomization • Various types of confounding • Inadequate matching of groups can bias results • NOT hypothesis proving

  23. Meta-analysis • A statistical technique • Combines pre-existing studies into 1 large study • Designed to produce new knowledge • A meta-analysis of well designed RCTs is considered higher level of evidence than any 1 RCT The quality of the meta-analysis depends entirely on the quality of the studies analyzed!

  24. Scandanavian study Koch et al. Small, randomized studies OR 1.16 (1.07 – 1.24) Wang et al. Transfusion 2011

  25. Meta analysis of odds risk of death in cardiac surgery patients Favors older stored blood Favors newer stored blood Wang et al. Transfusion 2011

  26. Age of Red Blood Cells in Premature Infants Study (ARIPI) • Prospective randomized trial • 377 premature babies born before 37 weeks, weighing <1250 g, admitted to ICU • RBCs < 7 days vs. standard issue • Average 5 days vs. 14 days • Primary outcome measures: • Necrotizing enterocolitis • Intraventricular hemorrhage • Bronchopulmonary dysplasia • Retinopathy of prematurity • Mortality No differences in outcomes!

  27. Another prospective randomized trial is already finished! • Stable, ventilated ICU patients • Received 1 unit of fresh RBCs (median 4 days) or standard issue RBCs (median 26.5 days) • At 2 hours post-transfusion measured: No differences in outcomes! Kor et al. Am J Respir Crit Care Med 2012;185:842

  28. אין דבר Conclusions • The biochemical changes of the storage lesion are real • The clinical data has by no means proven that the storage lesion effects are detrimental to recipients • What should be done about how the BB currently issues RBCs? Niets! Nichts! Nowt! Intet! Nothing! Ingenting! 33ff.com/flags

  29. Frick Park, Pittsburgh, PA en.wikitravel.org

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