Disease Burden and Pre-Transplant Health-Related Quality of Life in Pediatric Sickle Cell Disease Patients Receiving Nonmyeloablative HLA-Identical Sibling Donor Transplantation

Title: Disease Burden and Pre-transplant Health-related Quality of Life in Pediatric Sickle Cell Disease Patients Receiving Nonmyeloablative HLA-identical Sibling Donor Transplantation

Background: Sickle cell disease (SCD) is a hemoglobinopathy characterized by recurrent pain crises, severe organ damage, and reduced health-related quality of life (HRQL). Bone marrow transplantation (BMT) is a proven curative treatment for SCD that can improve both disease burden and HRQL. Despite the benefits, relatively few patients pursue a cure through BMT. The decision to receive a BMT is nuanced and likely to be influenced by a number of factors. One study by Roth et al. showed SCD patients interested in BMT had a higher HRQL than those uninterested in BMT, suggesting some variability between SCD patients pursuing transplant and the general SCD patient population. To date the factors that may affect pre-transplant HRQL of pediatric SCD patients remain unclear, particularly in the nonmyeloablative setting.

Objective: To evaluate the impact of disease-burden, patient demographics, and hydroxyurea treatment on pre-transplant HRQL.

Methods: Children and young adults with SCD set to receive a nonmyeloablative HLA-identical sibling donor BMT were administered HRQL surveys (PedsQL) in the six months leading up to the start of the conditioning regimen. Patients' disease history and demographic information were captured and analyzed for their relationship to HRQL. PedsQL parent surveys were used when patient surveys were unavailable. The mean difference in HRQL between groups were compared using an unpaired t test or linear regression.

Results: 32 patients were enrolled onto this study. Six of the 32 patients HRQL were not included due to withdrawal, delay of transplant, or completion of the survey outside of window. The median age at the time of survey administration was 13.5 years (range 2-21). 57.7% of patients were male and 88% of patients had genotypes hemoglobin SS or Sβ ⁰thalassemia. 12% of patients had a history of overt stroke. 52% of patients were hospitalized while receiving HU treatment. 32% of patients received chronic blood transfusions leading up to transplant. The median number of hospitalizations in the two years leading up to transplant was 2 (range 0-10). 16.7% of patients met the AAPT diagnostic criteria for chronic pain. 75% of patients received HU treatment leading up to transplant. The median hemoglobin F percentage was 10.4. The median HRQL for all patients was 77.17 (range 36.9-98.91, SD +/- 15.99).

Sickle cell genotype (P=0.88), history of overt stroke (P=0.79), hospitalization while receiving HU treatment (P=0.78), and the number of hospitalizations in the two years before transplant (P=0.39) were not associated with lower HRQL. History of chronic transfusion leading up to transplant approached statistical significance for lower HRQL (P=0.06). Older age (P=0.17) and female gender (P=0.89) were not associated with worse HRQL. Patients receiving HU treatment had significantly higher HRQL than patients not receiving HU (P=0.0034), with median PedsQL scores of 80.06 and 58.64, respectively. The date of survey administration was not associated with HRQL (P=0.40). The number of eligibility criteria met (P=0.63), chronic pain (P=0.17), total number of RBC transfusions (P=0.45), and pre-transplant hemoglobin (P=0.25) were not associated with HRQL.

Discussion: Patient demographics and several markers of disease burden appear to have minimal impact on HRQL. Interestingly, the use of HU therapy was associated with significantly higher pre-transplant HRQL. The etiology of this finding is unclear given that disease burden was not associated with HRQL and warrants further investigation. The absence of association between disease burden and HRQL through current disease severity eligibility paradigms suggests that other factors may impact HRQL in SCD patients choosing a low toxicity nonmyeloablative BMT.