Febrile Neutropenia and Bacteremia after High-Dose Chemotherapy and Autologous Hematopoietic Stem Cell Transplantation in Patients Treated Inpatient Versus Outpatient

Introduction Multiple myeloma (MM) is the most common indication for high dose chemotherapy and autologous hematopoietic stem cell transplantation (ASCT). In addition, patients with immunoglobulin light-chain amyloidosis (AL), a related plasma cell disorder, often benefit from ASCT. Objectives: We aimed to compare baseline demographics, peri-transplant mortality, and the incidence of febrile neutropenia and bacteremia between an outpatient transplant cohort at one institution and an inpatient cohort at a second institution. Methods We performed a two-center retrospective chart review of all patients with plasma cell disorders undergoing ASCT between January 2014 and December 2018. All patients at transplant center A. were managed in the outpatient setting unless admission was necessary for febrile neutropenia, gastrointestinal toxicity, cardiac complications, or other adverse events. All patients at transplant center B were managed in the inpatient setting from conditioning regimen to engraftment post transplant. Results A total of 183 patients were included (103 outpatients vs 80 inpatients). There were no significant demographic differences between cohorts [Table 1]. The outpatient cohort (transplant center A) had a higher proportion of patients with AL amyloidosis (61% vs 38%), and a higher proportion of patients who received full high-dose melphalan at 200 mg/m2. Within the outpatient cohort, 48/103 (47%) patients were admitted for febrile neutropenia and 39/103 (38%) required admission for other reasons post-transplant. There were no differences in the incidence of febrile neutropenia or peritransplant mortality between cohorts [Table 1]. However, the incidence of bacteremia was higher in the outpatient cohort (23.3% vs 8.8%, p Conclusion In this contemporary two-center cohort of patients undergoing ASCT, there is no difference in 100-day mortality or incidence of febrile neutropenia between inpatient versus outpatient protocols. In addition, we demonstrate that outpatient transplant is a safe option for patients with AL amyloidosis. Prior studies comparing inpatient versus outpatient ASCT have been single-center studies, in which younger patients or those with fewer comorbidities were selected for outpatient transplant. The increased incidence of gram negative bacteremia in the outpatient cohort is in keeping with at least one prior single-center study, and is associated with a higher incidence of regimen-related gastrointestinal toxicity. Ongoing analysis will explore the impact of induction therapy prior to ASCT and gastrointestinal toxicity grading (correlated with melphalan dosing) on the incidence of bacteremia.