Outpatient High-Dose Chemotherapy and Autologous Hematopoietic Cell Transplantation for Multiple Myeloma Is Associated with a Low Infection Safety Profile.

High-dose melphalan (MEL) and autologous hematopoietic cell transplantation (HCT) is now a standard therapy in patients (pts) with multiple myeloma (MM). This HCT procedure is sufficiently tolerable to be performed on either an outpatient (OP) or inpatient (IP) basis. We compared the infection profiles in 16 consecutive pts who underwent OP HCT and 31 consecutive pts who underwent IP HCT for MM over a 24-month period. The median age of each group was comparable (OP 58 yr, range 33–72 yr; IP 59 yr, range 32–74 yr). All pts received MEL 200 mg/m² before HCT and anti-infective prophylaxis with oral acyclovir, fluconazole and levofloxacin. Empiric treatment of first neutropenic fever in the OP group was imipenem and vancomycin (VAN) and in the IP group was cefepime with addition of VAN for persistent fever and/or positive cultures with VAN-sensitive bacteria. Median time to neutrophils >0.5 x 10⁹/L after HCT was 10 days in both groups (range 8–12 days for OP and 9–12 days for IP). Fever during neutropenia occurred in 7/16 (43.8%) of OP and 16/31 (51.6%) of IP HCT pts. Positive blood cultures (BCs) were identified in 3/7 (42.9%) of the febrile OP and 5/16 (31.3%) of the febrile IP HCT pts. Positive BCs in febrile OP HCT pts were coagulase-negative Staphylococcus (CNS) (2 pts) and Pseudomonas (1 pt). Positive BCs in febrile IP HSCT pts were CNS (2 pts), Streptococcus viridans (1 pt), Enterococcus (1 pt) and Bacillus (1 pt). One febrile OP HCT pt had cytomegalovirus pneumonia, and one afebrile IP HCT pt had a positive BC for CNS. Four febrile IP HCT pts with negative BCs had other infections, including cellulitis (2), facial abscess (1), and Clostridium difficile-associated colitis (CDAC) (1). Two other IP HCT pts (1 with fever and positive BC for CNS, 1 without fever) also had CDAC, for an overall incidence of CDAC of 3/31 (9.7%) after IP HCT. In contrast, no OP HCT pts had CDAC. Overall, the incidence of infections was 4/16 (25%) after OP HCT and 11/31 (35.5%) after IP HCT. We conclude that the infection profile of OP HCT compares favorably with that of IP HCT in pts with MM and is associated with a lower incidence of CDAC.