P0674 The impact of febrile neutropenia on incidence of febrile events (FE) in patients with acute myeloid leukemia (AML) Vladimir Okhmat*1, Galina Klyasova1, Elena Parovichnikova1, Elena Gribanova1, Valeriy Savchenko1 1National Research Center for Hematology, Moscow, Russian Federation Background: The aim of this study was to evaluate the impact of neutropenia on incidence of fever of unknown origin (FUO) and documented infections, including bloodstream infections (BSI), invasive mycoses (IM) and clinically documented infections (CDI) in patients with AML undergoing chemotherapy cycles (CC). Materials/methods: Prospective study in adults with newly diagnosed AML was performed in 2013- 2015. Patients were followed up for 180 days. Incidence of FE was evaluated on CC. IM were diagnosed according to EORTC/MSG criteria (2008). Results: There were 208 CC (94-induction, 114-consolidation) in 66 patients (28-male, 38-female; median age-39 years) with AML. Neutropenia was present in 194 (93%) of CC with median duration of 16 (17-55) days. FE occurred in 193 (93%) CC, the majority of them (62%) were attributable to documented infections (CDI-41%, BSI-14%, IM-8%), followed by FUO (38%). Acquisition of FE was 27% in CC without neutropenia and increased to 92-100% in CC with neutropenia (Fig.). In non-neutropenic patients all FE were represented by FUO. Incidence of FUO decreased from 46% to 21% with prolongation of neutropenia. Rate of CDI was similar (34-42%) regardless of neutropenia duration. BSI emerged only in CC with prolonged neutropenia (>7 days) with highest incidence (21%) in cases of neutropenia for 8-14 days. Incidence of IM was 2-4% in CC with neutropenia duration for 1-21 days and increased to 27% in cases of neutropenia for >28 days (p<0.05). Rate of carbapenem administration was 9% in non-neutropenic patients, 33-49% - in patients neutropenic for ≤14 days and 58-76% - in patients neutropenic for >14 days. Median duration of antibiotic treatment increased from 5 (3-14) days to 22 (7-61) days corresponding with lengthening of neutropenia. Figure. Incidence of documented infections and FUO in CC according to duration of neutropenia Conclusions: Incidence and type of FE is diverse regarding to neutropenia duration. FUO predominates in patients without or with short neutropenia. Documented infections tend to become more common in patients with persistent neutropenia. BSI and IM were diagnosed only in patients with prolonged neutropenia..