Outpatient Hematopoietic Stem Cell Transplant for Adult Sickle Cell Disease Patients Is Safe, Reduce Inpatient Bed Utilization and Improve Access to Care

Background

Sickle cell disease (SCD) is a common genetic disease in Saudi Arabia and the demand for curative allogeneic Hematopoietic stem cell transplantation (HSCT) is estimated to be more than 10 thousand patients. Allogenic HSCT requires the administration of conditioning regimens resulting in prolonged pancytopenia with heightened risk of infections and other complications. With the expansion of local transplant programs to meet this large demand, we frequently encounter delays in admissions due to the scarcity of beds.

The aim of this research is to study the safety and outcomes of outpatient transplants versus inpatient transplants for SCD patients.

Methods

In 2015, our center initiated HSCT program for SCD, performing an average of 50 transplants annually. The protocol involves the use of match related donors and a non-myeloablative regimen, which includes alemutuzmab, 300-cGy total body irradiation, and sirolimus for graft versus host disease (GVHD) prophylaxis.

In 2018, we decided to start outpatient HSCT with multiple objectives including reducing inpatient admissions, saving inpatient bed days, lowering the cost of transplants, increasing the number of transplants, and improving patients’ quality of life. Several interventions and changes have been made to achieve these goals.

We conducted a retrospective chart review of all SCD patients who had outpatient transplants from May 2018 to April 2024 and a control group who underwent inpatient transplants during same period. Baseline and transplantation characteristics and outcomes were compared using the Fisher exact test for categorical data and the Wilcoxon rank-sum test for nonparametric continuous variables. Analyses were performed using JMP version 17

Results

Sixty-eight patients underwent outpatient HSCT and 70 as inpatient. The median age was 24 years in the outpatient group and 24.5 years for inpatient group. The mean karnofosky performance score for outpatient 97% and 88.5% for inpatient group (p= 0.053). Median (Hematopoietic cell transplant – comorbidity index) HCT-CI 1 (0-4) for outpatient and 2 (2-5) for outpatient HSCT ( p= 0.017). Other patients’ characteristics were not statistically significant between both groups.

The total number of inpatient bed-days utilized was 2274 (75.8 months or 6.3 years) for the inpatient group, compared to 730 days for the outpatient group (p-value < 0.0001). Notably, the total number of bed days saved was 1193 days with a median of 19 bed days saved per patient in the outpatient setting. The total estimated cost saved is around 2,982,500 Saudi Riyals (795,333 USD).

Twenty-three patients (33.8 %) underwent their entire HSCT as an outpatient. The median days for outpatient course per patient was 19 days (+2, +24). The reasons for admissions varied widely, with the most common reasons being febrile illness (n=12, 17.6%), reactions to alemtuzumab (n=7, 10.2%), TBI-related complications (n=4, 5.8%), reactions following SCT infusion (n=2, 2.9%), nausea, vomiting, and diarrhea (n=3, 4.4%).

The median engraftment days for ANC and platelets were 17 and 18 days, respectively. In the inpatient group, 133 RBC units were transfused, compared to 95 units in the outpatient group. For platelets, the inpatient group required 1,315 units, whereas the outpatient group needed 1,015 units.

Infections rates were higher in the inpatient group. Respiratory infections were observed in 25.7% of the inpatient group, compared to 14.7% in outpatient group. Central line infections or bacteremia occurred in 8.5% in the inpatient setting, while only 1.4% of the outpatient experienced them. Similarly, febrile neutropenia was higher in the inpatient group, at 44.2% versus 39.7% in the outpatient group. On the other hand, GI infections were observed more in outpatient group 20.5% out of which 10.2% tested positive for C. Difficile versus 17.1% in inpatient setting.

One patient from inpatient group needed ICU admission, where none of the outpatient group needed a critical care setting. Both mortality and graft failure rates were zero at 3 months follow-up in both groups.

Conclusions

The Outpatient HSCT program for selected SCD patients appears to be feasible and safe. It offers a wide range of benefits such as improving inpatient bed utilization, improving access to care, with maintained quality of care and reduced cost. The outcomes are encouraging and support the development and expansion of the program in the future.