Recommendations for standardization of laboratory testing for drug‐induced immune thrombocytopenia: communication from the SSC of the ISTH

Abstract

Drug-induced immune thrombocytopenia (DITP) is a life-threatening clinical syndrome that is underrecognized and difficult to diagnose [1]. Clinical criteria can help determine the likelihood that a drug was the cause of thrombocytopenia, but confirmation of the diagnosis requires laboratory testing to demonstrate the presence of drug-dependent platelet antibodies. Test methods for these assays must be able to show (i) drug-dependence, (ii) immunoglobulin binding to platelets, and (iii) platelet specificity [2] and ideally should be reproducible across laboratories [3]. Current test methods are limited by the lack of standardization. There is a need to improve accessibility of testing for the most commonly implicated drugs, which means that the methods of testing including sample collection, handling of target platelets, drug concentrations, and the type of immunoassay should be standardized. Establishing uniform test methods and procedures will improve the reproducibility of results across laboratories and enable reliable comparisons. This ISTH recommendation document was developed to improve the standardization of laboratory testing for drug-dependent platelet-associated antibodies with the most frequently implicated prescription drugs: quinine, vancomycin, sulfamethoxazole/trimethoprim, and pipericillin/tazobactam. Recommendations were based on experience from three reference laboratories in the United States (Blood Center of Wisconsin), Canada (McMaster University), and Germany (Ernst-Moritz-Arndt-University Greifswald) and informed by discussions with members of the Platelet Immunology Scientific Subcommittee of ISTH.