Analysis of outcomes following change in granulocyte colony-stimulating factor administration policy in multiple myeloma patients receiving melphalan autologous bone marrow transplant

• Neutrophil engraftment was faster in the early G-CSF administration group compared to delayed administration by approximately 1 day • Median hospital length of stay was shorter with early G-CSF administration by 1 day • There was no statistically significant difference between G-CSF administration groups in engraftment syndrome occurrence Engraftment is a determining factor for hospital discharge following autologous hematopoietic stem cell transplant (auto-HSCT). Delays in engraftment can lead to a longer hospital length of stay (LOS), infection, and higher financial costs. In an effort to decrease the time to engraftment, Intermountain Health’s Blood and Marrow Transplant Program modified the start time of granulocyte colony-stimulating factor (GCSF) initiation from Day +6 to Day +1. This study is a post-implementation retrospective review to determine if this practice change affects engraftment, hospital LOS, engraftment syndrome (ES) occurrence, and overall survival (OS). The review was conducted among multiple myeloma and plasma cell disorder patients 18 years or older who received melphalan-based auto-HSCT at LDS Hospital. Comparison groups are those that received G-CSF on Day +6 after transplant (control) compared to Day +1 (intervention). Data was obtained via chart review and from preexisting program databases. Time to engraftment was measured as days from stem cell infusion until neutrophil engraftment, defined as the last of three consecutive days with an absolute neutrophil count (ANC) of 0.5 × 108/L or higher. As the primary outcome, time to engraftment was analyzed via a statistical t-test. Patients with suspected ES were identified by both the administration of steroids beyond transplant Day 0 and through chart documentation of ES. Lastly, 1-year OS post-transplant was evaluated. Differences in time to engraftment, hospital LOS, rate of ES, OS, and cost were compared between groups with both descriptive and inferential statistics. Confounding factors, including clinically significant baseline characteristics, were analyzed through multivariate regression analysis. Between February 1, 2017, to October 24, 2022, 137 patients underwent melphalanbased auto-HSCT, with 129 patients included in the final analysis. At an average age of 62 years, the majority of patients were male, Caucasian, with multiple myeloma in CIBMTR stage of very good partial response (VGPR) and previous bortezomib, lenalidomide, and dexamethasone (VRd) induction therapy. Neutrophil engraftment was faster in the early administration group compared to delayed administration by approximately 1 day (95% CI -1.47 ̶ -0.79); p < 0.001). Median hospital LOS was also shorter with early G-CSF administration by 1 day (95% CI -3 ̶ -1, p < 0.001). There was no statistically significant difference between groups in ES occurrence or in OS at 1 year. Utilization of empiric antibiotics were similar, with shorter duration in the early administration group (difference 3.1 days). Finally, facility cost per patient transplant stay was lower with Day +1 G-CSF administration. Day +1 G-CSF administration has similar safety and efficacy to Day +6 G-CSF administration in patients receiving melphalan-based auto-HSCT. In fact, Day +1 administration may have improved efficacy outcomes, with 1 day shorter time to engraftment and hospital LOS.