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TRM JC – September 11, 2007 Maggie Constantine, MD, FRCPC Resident, Transfusion Med

Transfusion from male-only versus female donors in critically ill recipients of high plasma volume components Crit Care Med 2007, 35(7):1645-1648. TRM JC – September 11, 2007 Maggie Constantine, MD, FRCPC Resident, Transfusion Med. Overview TRALI – same, but not equal.

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TRM JC – September 11, 2007 Maggie Constantine, MD, FRCPC Resident, Transfusion Med

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  1. Transfusion from male-only versus female donors in critically ill recipients of high plasma volume componentsCrit Care Med 2007, 35(7):1645-1648. TRM JC – September 11, 2007 Maggie Constantine, MD, FRCPC Resident, Transfusion Med

  2. OverviewTRALI – same, but not equal • Anti-HLA and/or anti-granulocytic antibodies in donors • Male donors - <1% • Female donors – 17% overall • Significantly correlated with parity • 0-3 pregnancies -> 7.8 to 26.3% • Anti-neutrophil antigen antibodies • Very low Densmore TL et al. Transfusion 1999;39(1):103-6

  3. OverviewTRALI – smoking gun? • Palfi M et al. Transfusion 2001;41:317-322. • “… is plasma from multiparous blood donors dangerous?” • 5 post transfusion reactions • 4 reactions post multiparous females plasma • Significantly lower oxygen saturation and higher TNFα concentrations

  4. OverviewTRALI – smoking gun? • UK experience • 2003 • Male donors to be used, as far as possible, for • FFP • plasma for suspension of buffy coat derived platelet pools (60% of platelet production) • Achieved for >90% FFP; >85% platelet pools • 2004-2005 • Decrease in number of TRALI and number of TRALI-related deaths Chapman CE et al. Vox Sang 2006;91(s3): 227

  5. OverviewTRALI – smoking gun? • American experience, 2003-05 • 35 ARC blood centers – active solicitation for AEs • Fatalities probably due to TRALI • 72 reported fatalities linked to TRALI • 38 fatalities “probably” TRALI • 63% post plasma transfusion • Female WBC antibody + donors significantly more likely to be associated with probable TRALI cases Eder AF et al. Transfusion 2007;47:599-607

  6. OverviewTRALI – smoking gun? • Canadian perspective • 2001 to 2006 • N=53 definite and possible TRALI • 11.9% plasma (65.7% high plasma volume-containing components) • RBC 35.5% • 46.8% of donors were female • 33 cases – donor + for antibodies • 14 cases-females, 9 cases-male, 10-both Lin Y et al. Transfusion Med 2007;17:225-249

  7. OverviewTRALI – the cavalry arrives • aaBB Association Bulletin – Nov 3, 2006 • “Blood collecting facilities should implement interventions to minimize the preparation of high plasma-volume components from donors known to be… at risk of leukocyte alloimmunization.” • “Preparing high plasma-volume components intended for transfusion from male donors.” • Canadian Blood Services – July 2007 • Similar policy to start September 2007

  8. Crit Care Med 2007 Vol.35, No.7

  9. MethodsCrit Care Med 2007 Vol.35, No.7 • Retrospective, case-controlled • 1999-2005 • 4 ICUs: 1 med, 2 surg, 1 mixed • Mayo Clinic • Consecutive patients who received > 2 units FFP or apheresis platelets • Exclusions: “patients who refused research authorization”

  10. MethodsCrit Care Med 2007 Vol.35, No.7 • Patients (‘cases’) • Received high plasma volume components from only male donors • Controls • Patients who had received 3 or more female-donor components with or without additional male components • Matched for • Severity of illness • Postop state • Number of transfusions • 3 or more female donations +/- additional male components Afessa B et al. Mayo Clin Proc 2005;80:174-180.

  11. MethodsCrit Care Med 2007 Vol.35, No.7 • Main outcomes • Development of acute lung injury (ALI) • American European Consensus Conference • Post-transfusional hypoxemia • PaO2/FiO2 • Hospital mortality • Duration of mechanical ventilation

  12. ResultsCrit Care Med 2007 Vol.35, No.7

  13. ResultsCrit Care Med 2007 Vol.35, No.7 • PaO2/FiO2 • In 49 matched pairs with ABGs pre- and post-transfusion • Worsened significantly after the female • Indications for transfusion (FFP and/or platelets) • Active bleeding – 35% • Postoperative anemia – 16% • Severe thrombocytopenia – 4% • Plasma exchange – 1% • Other – 9% • “25% of patients received transfusions outside practice guidelines”

  14. DiscussionCrit Care Med 2007 Vol.35, No.7 • Limitations • Differences in measured and unmeasured prognostic factors may decrease the confidence in observed findings and limit causal inference • Absence of female donor parity data • Discrete imbalance in pre-transfusion PaO2/FiO2

  15. ConclusionsCrit Care Med 2007 Vol.35, No.7 • “critically ill recipients of high plasma volume components from male-only donors had… • less impairment of gas exchange… [and] • higher number of ventilator-free days” • “prospective studies are needed to evaluate the effects of AABB recommendations not only on the incidence of TRALI… but also on morbidity and mortality of transfused critically ill patients.”

  16. Critical AppraisalCrit Care Med 2007 Vol.35, No.7 • Are the results of the study valid? • Retrospective • ICU patients • EXCLUDED: neurology, pediatric, coronary or CV surgery ICUs • Case-controlled • But may fit definition of ‘cohort’ better • Would be ‘case-control’ if cases of TRALI identified and then rates of female plasma exposure determined

  17. Critical Appraisal – Cohort studiesCrit Care Med 2007 Vol.35, No.7 • Why cohort study? • ‘natural experiments’ in which outcomes measured in ‘real world’ rather than experimental settings • Can evaluate large groups of diverse individuals • Longer follow-up • Useful if outcomes – such as adverse events – are rare • Large samples needed for RCTs are prohibitive Rochon PA et al. BMJ 2005;330:895-896.

  18. Critical Appraisal – Cohort studiesCrit Care Med 2007 Vol.35, No.7 • Comparison groups • “counterfactural’ or “potential outcome” • Ideal comparison group • Does not exist in reality • General population • Intervention v alternative intervention • Intervention v no intervention • Restricted population • Intervention v alternative intervention • Intervention v no intervention Rochon PA et al. BMJ 2005;330:895-896.

  19. Critical Appraisal – Cohort studiesCrit Care Med 2007 Vol.35, No.7 • Potential pitfalls • Selection bias • A systemic error in creating intervention groups • Differ with respect to prognosis • Measured or unmeasured • Confounder • A situation in which the estimated intervention effect is biased • Factor must differ between the comparison groups and predict the outcome of interest Rochon PA et al. BMJ 2005;330:895-896.

  20. Critical Appraisal – Cohort studiesCrit Care Med 2007 Vol.35, No.7 • How can these pitfalls be amended? • Inclusion restriction • Regression – adjusted effect • Linear • Logistic • Proportional hazards • Stratification – division of sample into subgroups for confounding factors • Effects of intervention are then measured within each subgroup Rochon PA et al. BMJ 2005;330:895-896.

  21. Critical AppraisalCrit Care Med 2007 Vol.35, No.7 • Are the results valid? Unclear • Retrospective, cohort study • No power calculations • Apparent elimination of selection (indication) bias • Assignment of transfusion products, with respect to donor gender, was by chance

  22. Critical AppraisalCrit Care Med 2007 Vol.35, No.7 • Potential confounders – no regression analyses or stratification • Measured • Renal replacement therapy • Pre-transfusion edema • Not measured • Risk factors for ALI • Pneumonia, shock, multiple trauma, burn injury, acute pancreatitis, drug o/d • Red cell usage • Female donor parity • Presence of anti-HLA, anti-neutrophil Abs in donor / recipients

  23. Critical AppraisalCrit Care Med 2007 Vol.35, No.7 • Were exposures and outcomes measured in the same way? YES • +/- hypoxemia, ALI, risk factors for ALI were ascertained by co-investigators blinded to the specific transfusion characteristics • Was follow-up sufficiently long and complete? Unclear • Follow-up not explicitly stated • Any patients missing data? – not stated

  24. Critical AppraisalCrit Care Med 2007 Vol.35, No.7 • Temporal relationship correct? YES • Dose-response gradient? NOT studied • What is the magnitude of risk? • Relative risk of ‘new ALI’ = 0.75 • Relative risk of ‘post-transfusion hypoxemia’=1.21 • Absolute risk increase of PTH = 12% • Number needed to treat to see harm = 8 • How precise is this estimate of risk? NO CI provided

  25. Critical AppraisalCrit Care Med 2007 Vol.35, No.7 • Should I attempt to stop the exposure? • Not based on this study • Narrow adult ICU population • No power calculations: underpowered for ‘new ALI’? • Unclear clinical relevance of increase in post-transfusion hypoxemia • Trend towards increased hospital mortality and significantly fewer vent free days • But cannot say if the relationship is causal

  26. Critical AppraisalCrit Care Med 2007 Vol.35, No.7 • Context within current evidence • Post-transfusion hypoxemia • Consistent with Palfi et al. 2001 • TRALI • Consistent with Canadian experience (Lin et al. 2007) • Future Research: Prospective cohort • Case – female +/- male donor transfusion products • Control – male only • Determine HLA antibody status of products • Outcome – TRALI and / or post-transfusion hypoxemia (clinical relevance?)

  27. Transfusion from male-only versus female donors in critically ill recipients of high plasma volume componentsCrit Care Med 2007, 35(7):1645-1648. TRM JC – September 11, 2007 Maggie Constantine, MD, FRCPC Resident, Transfusion Med Comments? Questions?

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