Incidence, etiology and timing of infections following azacitidine therapy for myelodysplastic syndromes.

We examine the infective complications occurring during azacitidine (AZA) therapy in patients with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). A retrospective review of patients receiving ≥1 cycle of AZA for MDS or AML was performed. Patient demographics, infection prophylaxis/episodes and outcomes were evaluated. Sixty eight patients received 884 AZA cycles. Bacterial infections occurred in 25% of cycle-1 and 27% of cycle-2 AZA therapy. Febrile neutropenia complicated 5.3% of AZA cycles, bacteremia 2% and invasive Aspergillosis 0.3%. Using Poisson modeling, a very high IPSS-R (RR 10.26, 95% CI 1.20, 87.41, p= .033) was identified as an independent risk factor for infection. Infection-related attributable mortality was 23%. The burden of infection is high in AZA-treated patients, associated with high attributable mortality. Over 25% of AZA cycles 1 and 2 were complicated by infection, predominantly bacterial, rates dropping to <10% after cycle-5.