#32 Pediatric Febrile Neutropenia with Low Risk of Systemic Infection: When Is It Safe to Stop Antibiotics?

Abstract

Abstract Background There are no standard practices about antibiotics duration in unexplained stable febrile neutropenia (FN). Absolute neutrophile count (ANC) recovery has been used clinically to represent bone marrow recovery (BMR) but data about safe ANC threshold for antibiotic cessation (AC) and discharge is still unknown. Other markers should be considered. We hypothesized that absolute monocyte count (AMC), and absolute phagocyte count (APC= ANC + AMC+ bands) are more sensitive, and an earlier safe marker of AC compared with ANC Method A retrospective review was performed for FN episodes (FNEs) at a single institution (2009 and 2016) in pediatric oncology patients. Eligible FNEs who were a febrile for 24 hours and had no documented infectious source identified at AC and did not receive chemotherapy 10 days following AC. Ten-day post-AC primary end points (recurrent fever, readmission, blood stream infection BSI, microbiology documented infection MDI, and adverse outcomes) were assessed and compared among different BMR parameters (ANC vs AMC vs APC). Secondary end point compares length of stay, antibiotics free days and cost-effectiveness among different BMR markers. Results Eligible FNEs were 391 at time of AC in 235 patients. Three groups were compared based on ANC (cells/μL) at the time of AC : < 200 in 102 (26%), 200-500 in 111 (28%), and >500 /uL in 178 (46%) with an overall ten-day recurrent fever rate 7.4% (29/391). No significant differences in primary end point outcomes rates were identified among 3 ANC groups (11.7%,, 6.3% and 5.6% respectively, P=0.06) and readmission (10%,4.5%, 4%, respectively; P=0.05)(Table 1), however, there is a trend toward unfavorable outcomes in ANC< 200 group compared with ANC>200. In subset analysis in group of ANC>200, favorable outcomes in (ANC>200 with AMC>100) than in the (ANC>200 with AMC<100) group. There was significant risk reduction in primary end points (75% in recurrent fever, 85% readmission, 87% in BSI, 88% in MDI and 87% in adverse events in (ANC>200 with AMC>100) compared with (ANC>200 with AMC<100/uL) group. More importantly, primary end points based on AMC>100 /uL as BMR for AC, regardless ANC values, showed significant favorable outcomes compared AMC<100 /uL. There is 80%, 88, 90%, 89%, and 93% risk reduction in end points recurrent fever, readmission BSI, MDI, and adverse outcomes respectively. Similar favorable results were seen when APC>300 used as threshold for AC (Table 2, 3). Median of length of stay of FN was 3 days shorter using AMC >100/uL for BMR compared with any threshold of ANC (P< 0.01) and decrease overall FN cost stay (P< 0.01). Conclusion Our results suggest that AMC > 100 /uL regardless of ANC/uL, or APC> 300 or ANC>200 with AMC>100/uL all are a safe thresholds for empiric AC. Further prospective studies are needed to validate AMC as accurate surrogate for AC in FN children with cancer.