Assessment of a cytomegalovirus serology dual-testing strategy in hematopoietic stem cell transplant recipients

Background: Accurate determination of recipient cytomegalovirus (CMV) serostatus before allogeneic hematopoietic stem cell transplantation (HSCT) is critical, as it is the most important predictor of post-transplant CMV infection and remains associated with non-relapse mortality. The purpose of this study was to assess a recipient dual-testing strategy before HSCT. Methods: CMV serologic testing was performed before allogeneic HSCT using 2 different assays: reference laboratory (RL) and American Red Cross (ARC). In all cases, blood samples were obtained for RL testing either before ARC testing (median 130 days before HSCT [range 12–2594]) or at the same time (median 25 days before HSCT [range 8–129]). The results of serologic testing were correlated with CMV viremia post HSCT. Results: Of 287 recipients evaluated, 76 (26.5%) had discordant results, of which 74 (97.4%) tested RL−/ARC+. Ten had RL and ARC testing performed on simultaneously obtained samples, 3 of which (30%) were discordant (3 [100%] RL−/ARC+). Acute myeloid leukemia and receipt of blood product transfusion in the interval between testing were associated with RL−/ARC+ discordance. Correlation with viremia after HSCT suggested that RL−/ARC+ discordance was caused by detection of anti-CMV immunoglobulin transferred in transfused blood products and reduced specificity of the ARC assay. Conclusion: CMV-seronegative hematopoietic stem cell transplant recipients may be misclassified as seropositive if testing is performed after receipt of blood products or when using assays optimized for sensitivity at the expense of specificity. This misclassification may negatively affect post-HSCT outcomes for individual patients and studies that rely on accurate CMV serology reporting.