Page 28 - Haematologica March 2020

S.L. Thein et al.
logical evaluation. To avoid these challenges, routine serological testing should be considered for all SCD patients 1 to 3 months after each transfusion episode.42 Even with such a policy in place, up to 30% of DHTR with bystander hemolysis occur in the absence of any detectable alloantibody,14,26 making it particularly difficult to predict and prevent these transfusion reactions fully.
Shared laboratory data between hospital systems is critical
Significant barriers to laboratory information exchange exist in many healthcare systems in many countries, and efforts that allow alloantibody identification histories of all patients (including those with SCD) to be shared between such systems must become a priority. This criti- cal patient safety initiative would facilitate antibody iden- tification in a patient’s sample, would decrease the burden of identifying optimal RBC units when working with incomplete transfusion histories, would increase the time- ly provision of fully compatible RBC units, and would decrease the incidence of DHTR.38,39 Currently, the lack of such data sharing prevents many transfusion services from knowing the transfusion requirements of newly encoun- tered patients with SCD at the time of a transfusion request,40 or from knowing the availability of compatible RBC once alloantibodies have been characterized.11,43 If complex alloantibody profiles were known a priori and corresponding donor databases were available, compati- ble donor units could be readily identified, allowing trans- fusion requirements to be addressed in a more timely and safe manner.38,39,44
Routine post-transfusion antibody screening and HbA quantification should be considered to improve identification of red blood cell alloantibodies
and delayed hemolytic transfusion reactions
Although additional studies are certainly needed to establish the incidence of DHTR in various hospital set- tings, more uniform detection of these reactions is
important if future DHTR are to be avoided and if effec- tive treatment strategies are to be implemented.45 While patients may experience accelerated clearance of trans- fused RBC in the absence of clinical systems, to facilitate detection of clinically meaningful DHTR, we recom- mend that patients with SCD with a history of transfu- sion in the preceding 21 days who present with any com- plication requiring medical attention should be evaluated with an antibody screen regardless of whether or not another RBC transfusion is warranted. Using this approach, a higher percentage of alloantibodies that form as a result of a recent transfusion should be identi- fied. However, as nearly 30% of DHTR have been reported to occur in the absence of detectable alloanti- bodies,14,26 evaluation for DHTR will also require acquisi- tion of HbA values following transfusion and at the time of clinical presentation of any complication requiring medical attention.27 As episodic transfusions are much more likely to be initiated during acute complications and result in DHTR,6,7,27 polices that include obtaining HbA values within 48 h following an episodic transfu- sion may be particularly helpful when interpreting a HbA value at the time of suspected DHTR. Thus, we rec- ommend considering routine HbA measurements fol- lowing any episodic RBC transfusion and an antibody screen and HbA measurement at the time of any hospital presentation within 21 days of the most recent episodic transfusion (Table 1).
Therapeutic options for ongoing delayed hemolytic transfusion reactions
In addition to facilitating more accurate diagnoses of DHTR, routine approaches aimed at identifying DHTR will allow consideration of more effective therapeutic options for ongoing DTHR; these therapies are particular- ly important to consider for DHTR involving hyperhe- molysis. Erythropoietin and intravenous iron are often given to boost endogenous RBC production in a setting of severe anemia.12 Plasmapheresis has also been attempted
Table 1. Recommendations for better prevention, more accurate diagnosis and improved treatment of delayed-type hemolytic transfusion reac- tions in sickle cell disease.
Prevention:
National and International
1) RBC alloimmunization databases 2) RBC donor databases
Institutional
1) Reduce RBC alloimmunization through prophylactic matching for Rh (C/c, E/e) and K antigens.
2) Judicious use of RBC transfusions
3) Routine alloantibody evaluation for all patients with SCD within 1 to 3 months after each episodic transfusion (while rare, some alloantibodies may
not be detectable within 3 months after transfusion)
Diagnosis:
Institutional
1) Alloantibody screen for any SCD exacerbation within 21 days of transfusion (regardless of whether another transfusion is being considered) 2) HbA quantification within 48 h following episodic transfusion and at the time of any SCD exacerbation occurring within 21 days of a transfusion
Treatment: Institutional
1) Supportive care (including erythropoietin and iron)
2) Intravenous immunoglobin and corticosteroids
3) Consideration of treatment with complement inhibitors in cases of severe DHTR (including those with hyperhemolysis)
4) Consider rituximab prophylaxis in cases with a history of severe DHTR and only “least incompatible” blood can be sourced for transfusion.
RBC: red blood cell; SCD: sickle cell disease; HbA: hemoglobin A.
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haematologica | 2020; 105(3)