Efficacy, Safety and Cost Implications of Outpatient Autologous Hematopoietic Stem Cell Transplant for Multiple Myeloma: A Single Center Experience
Authors: Marini Jessica , Maldonado Andy , Weeda Erin R , Hashmi Hamza , Neppalli Amarendra K. , Edwards Kathy 
Published: February 2021

Introduction:
Autologous hematopoietic stem cell transplant (aHCT) has become a standard of care for patients with multiple myeloma (MM). Outpatient aHCT with high dose melphalan conditioning has been shown to reduce costs and length of hospital stay. This study highlights the efficacy, safety and cost implications of outpatient versus (vs) inpatient aHCT with the initiation of an outpatient aHCT program at a tertiary academic medical center, as well as the utility of growth factor use in these patients.
Methods:
Using the institutional HCT database, a total of 100 patients undergoing aHCT for MM were identified to compare 50 patients that underwent aHCT in the outpatient setting since May 2018 to 50 patients that underwent aHCT in the inpatient setting prior to May 2018. Patients in the inpatient group were admitted on day -2 with a planned discharge on day +1 for an anticipated length of stay of 4 days, whereas patients in the outpatient group received chemotherapy and stem cells in the outpatient setting. Patients were then hospitalized as needed for febrile neutropenia or other complications requiring supportive care. Patients were excluded if the melphalan dose was less than 200 mg/m2. Data collection was conducted via retrospective chart review. Outcomes assessed included time to absolute neutrophil count (ANC) and platelet engraftment, incidence of infection and febrile neutropenia, growth factor use, and total length of inpatient stay through day +100.
Results:
Time to neutrophil and platelet engraftment was shorter for the outpatient group as compared to the inpatient group (14 vs 16 days and 19 vs 21 days, P &lt;0.001, respectively). The incidence of infection (~30%) and hospitalization following stem cell infusion (~90%) were similar between the two groups. However, the median length of stay and incidence of more than one hospitalization following transplant were significantly lower in the outpatient group compared to the inpatient group (8.5 vs 15.5 days and 4% vs 26%; P &lt;0.001, respectively). The total number of hospital days were 889 days for the inpatient population and 437 days for the outpatient population for a total reduction of 452 hospital days. The median dose of melphalan was similar between m the two groups (352 mg for the outpatient group vs 348mg for the inpatient group). Based on the institutional costs from August 2020, purchase and administration of melphalan for the outpatient utilization results in an estimated cost savings of $216,000 for every 50 patients.
Of the 44/50 (88%) patients in the outpatient group that required hospital admission, 40/44 (90%) had neutropenic fever. A total of 24/40 (60%) of these patients were given growth factor support starting at a median of 9 days (range 4 - 16) after stem cell infusion for a median duration of 4 days (range 1 - 8). When compared to the group of 16 patients that did not receive growth factor, there was a difference in time to neutrophil engraftment (13 days with vs 15 days without growth factor, P = 0.02) There were no significant differences in the time platelet engraftment (20 days with vs 19 days without growth factor, P = 0.20) or length of hospital stay (8 days with vs 10 days without growth factor, P = 0.43).
Conclusion:
For adult patients with multiple myeloma undergoing aHCT, the outpatient setting is not only safe and effective, but also reduces total length of hospital stay and overall cost of transplant. Growth factor support for patients with febrile neutropenia may not reduce length of hospital stay.

Disclosures
Neppalli: Sanofi: Membership on an entity's Board of Directors or advisory committees. Edwards:Genzyme: Membership on an entity's Board of Directors or advisory committees.