Disparities in Cytomegalovirus Infection Rates by Race and Ethnicity among Pediatric Allogeneic Hematopoietic Cell Transplantation Recipients at a Single Center

Abstract

Previous literature has reported cytomegalovirus (CMV) infection rate disparities among racial/ethnic groups of hematopoietic cell transplantation (HCT) recipients. Because race and ethnicity categorizations are social constructs unlikely to affect biological systems, it is likely there are covariates on the pathway to CMV detection, known as mediators, that can explain the observed disparity. Recent developments in mediation analysis methods enable the analysis of time-to-event outcomes, allowing an investigation of these disparities to also consider the timing of CMV infection detection relative to HCT. This study aimed to explore whether racial and ethnic CMV infection disparities existed within a population of HCT recipients at our center, and whether clinical covariates explained any observed association. The study cohort included all recipients of allogeneic HCT performed at the Children's Hospital of Philadelphia between January 2004 and April 2017 who were CMV PCR-negative pretransplantation, had known donor/recipient CMV serology, and were under blood CMV PCR surveillance. Subjects were followed for 100 days post-HCT. Accelerated failure time models using subject's reported race/ethnicity, dichotomized into non-Hispanic White (NHW) and non-NHW, and exposure and time to CMV detection as outcomes examined whether selected clinical factors-donor/recipient CMV serostatus, recipient age, indication for HCT, hematopoietic cell source, match quality-mediated any identified exposure-outcome association. The analysis included 348 HCTs performed in 335 subjects, with 86 episodes (24.7%) in which CMV was detected via PCR analysis. The accelerated failure time model without mediators estimated that non-NHW subjects had fewer CMV-free survival days (time ratio, .21; 95% confidence interval, .10 to .44). Any hypothesized mediator mediated at most 5% of the total association between race/ethnicity and time to CMV detection. Non-NHW HCT recipients had fewer CMV-free survival days than NHW recipients; none of the clinical factors hypothesized to mediate this association accounted for a significant component of total association. Further research should focus on nonclinical factors influenced by systemic racism to better understand their effect on CMV infection among HCT recipients.