*Purpose: Neutropenia is a common side effect of valganciclovir and may pose increased risk for post-transplant infections. Medications such as mycophenolate and infections such as CMV also contribute to neutropenia risk. We sought to determine the incidence of infections in patients who did or did not develop neutropenia post-transplant.

*Methods: Of 1076 kidney transplant recipients at our center from 2010-2014, we identified 393 patients (36.5%) who had developed neutropenia at any time post-transplant (ANC < 1000 cells/mm³, “neutropenic group”), and 683 (63.5%) who never developed neutropenia (“non-neutropenic group”). Data were collected on demographics, transplant characteristics, immunosuppression, and infections over 3 years post-transplant. Mild outpatient infections were excluded. We used multivariable Poisson regression to evaluate the association between neutropenia and rate of infection.

*Results: Most common infections were urinary tract (in 34.5% overall), CMV (17.8%), pulmonary (17.5%), and bloodstream (12.5)%; all of these were more common in the neutropenic group (p for all < 0.02). In the neutropenic group, 34.2% had CMV DNAemia at some point, vs. 8,4% in the non-neutropenic group (p<0.001). Neutropenic fever occurred in 3.6% of the neutropenic group. Bloodstream infections occurred in 16.8% of the neutropenic group vs 10% of the non-neutropenic group (p=0.001).

*Conclusions: The development of neutropenia at any time post-transplant identifies a group with an increased incidence of infections, compared to patients who never develop neutropenia. Causality is complex since infections may either result from, and contribute to, neutropenia. Further studies will be important in designing strategies for prevention of post-transplant neutropenia and associated infections.

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