By
Neil Blumberg
Research letter in NEJM describes our findings. https://www.nejm.org/doi/full/10.1056/NEJMc2034764?fbclid=IwAR1BQRvpaHBAMDaHxCPY07xBjPQHlIHoJCOmpjoT_pBNvQsV7pzzDVdLYaY
Table 1. HLA-Matched Platelets as a Percentage of All Platelet Transfusions, According to the Initiation of Other Protocols.*
Protocol and Timing of Initiation
No. of Years
HLA-Matched Platelets
Difference from Previous Period (95% CI)
median % (IQR)
percentage points
No leukoreduction and no ABO matching (1985–1990)
6
12.5 (4.2–13.7)
NA
Leukoreduction and ABO matching for patients with leukemia and MDS (1991–1999)†
5
2.9 (2.0–3.6)
9.6 (9.4–9.8)
Universal leukoreduction (2001–2004)
4
1.4 (1.1–2.0)
1.5 (1.4–1.6)
Universal ABO matching (2005–2015)
11
0.4 (0.2–0.8)
1.0 (1.0–1.1)
Pathogen reduction of platelets (2016–2019)‡
4
1.7 (0.8–1.8)
ND
The practical fact is that this can only be implemented by medical technologists, not physicians, and this is a daunting prospect. But the reality is that ABO mismatched platelet transfusions probably exacerbate rather than prevent bleeding, so waiting for ABO identical is likely better than just transfusing whatever is available. This is going to require a major change of approach because the (incorrect) dogma, based upon no data, is that ABO doesn't matter for platelets.
I understand why many people's instant reaction is this is not feasible. But it is once technical experts in your transfusion service figure out how to implement it gradually. In our randomized trial back in 1993 (see ref below), the ABO identical group only required <50% the number of platelet transfusions (every other day instead of every day on average) compared with the usual first in, first out regardless of ABO type group. ABO mismatched transfusions create a hostile environment with gigantic immune complexes that compromise subsequent transfusion that may be ABO identical. Avoiding this is key.
Our suggestion is to start gradually. Pick new previously untransfused patients with aplastic anemia and good prognosis AML (young, favorable or normal cytogenetics), groups O or A, and start with them. Eminently doable since your platelet supply is 45% O and 40% A, just like your patients, on average. Get the hang of doing this and prioritizing ABO for at least some patients. Once you get this in place, extending it to other patients and eventually all patients can happen. We use washed O or A platelets and red cells for group B and AB recipients when we don't have group B or AB platelets. No increase in bleeding and fewer transfusion reactions, lung injury and congestive heart failure (what we call TRALI and TACO).
In the end, you have more surviving patients and fewer headaches and transfuse many fewer platelets per patient and essentially no HLA if you can get your referring hospitals to stop our current standard harmful practices. Godspeed. Heal JM, Rowe JM, McMican A, Masel D, Finke C, Blumberg N. The role of ABO matching in platelet transfusion. Eur J Haematol. 1993 Feb;50(2):110-7. doi: 10.1111/j.1600-0609.1993.tb00150.x. PMID: 8440356.
Happy to have discussions or visitors so our technical experts can show you how it is feasible.
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