Wisconsin Diagnostic Laboratories Milwaukee, United States
Background/Case Studies: Anti-CD38 drugs have been used for treatment of Multiple Myeloma since 2015. All anti-CD38 drugs interfere with routine blood bank testing. Most recommendations for transfusion practices are to phenotype or genotype the patient for Rh, Kell, Duffy, Kidd, and MNS blood group antigens prior to transfusion. Patients will then receive phenotypically matched RBCs if anti-CD38 begins to interfere with testing. The aim of this study is to evaluate the benefits of using in-house treated Dithiothreitol (DTT) antibody screens.
Study
Design/Methods: A retrospective review over a two-year period of patients known to be receiving anti-CD38 drugs was performed to analyze how often these patients appear to make new alloantibodies. A comparison was also made with smaller local hospitals from the same system that do not perform in-house DTT testing and send all positive antibody screens to the Immunohematology Reference Lab (IRL).
Results/Findings: There were 285 patients receiving or about to receive an anti-CD38 drug. Of these patients, 60% experienced interference with antibody screens in solid phase. There were 514 DTT screens performed over the two years. One screen (0.19%) was positive and sent to the IRL for further workup. No underlying antibodies were found. Three patients (1%) had previously identified antibodies (anti-K and two anti-Jka) prior to receiving anti-CD38. No new antibodies were detected in any of the 285 patients.
The cost of sending anti-CD38 testing to the IRL is $493-888, not including the initial type and screen (TS) performed in house. Our hospital bills the in-house DTT screens the same as a standard TS order. The average cost of a TS in the US was approximately $300 in 2021. A negative DTT antibody screen allows our blood bank to electronic crossmatch RBC units instead of providing incompatible crossmatched units or genotyped matched units. All hospitals in the system provide units that are K or k matched, but the smaller hospitals will send a patient sample for genotyping. The testing sent to the IRL can take anywhere between 24 to 72 hours, whereas the in-house testing using DTT treated cells enables RBC units to be released in approximately one hour from sample receipt.
Conclusions: Performing in-house DTT antibody screens affords quicker TAT, decreases costs due to eliminating IRL send outs, and allows patients to receive blood products during their same day appointment. This minimizes visits to the hospital and makes it easier for patients with specific transportation needs. DTT antibody screens are also beneficial by decreasing crossmatch cost, complexity, and TAT.
