Understanding Causes of Disparate Outcomes in Pediatric Acute Leukemia: Social Vulnerability Index As a Predictor for Increased Hospitalizations for Infections during Intensive Chemotherapy
Authors: Gillespie Nali , Brantley Alexis , Viviano Morgan , Feng Zhide , Smith Leah , Velez-Yanguas Maria C C. , LeBlanc Zachary 
Published: December 2024

Outcomes for pediatric leukemia are excellent due to modern cooperative group treatment protocols and advances in supportive care. Despite the progress made, disparities persist among patients from minoritized and lower socio-economic backgrounds. The underlying causes and extent of these disparities are not fully understood. Infections remain a significant cause of morbidity and mortality in pediatric leukemia patients. We hypothesized that vulnerabilities associated with social determinants of health (SDoH) would correlate with a higher incidence of infections requiring hospitalization during intensive chemotherapy in pediatric patients with acute leukemia.

Following IRB exempt status approval, a retrospective chart review was performed on 94 patients treated during the first 6 months of chemotherapy for acute leukemia at a tertiary care pediatric hospital from 2017 to 2024. Located in an underserved state in the Southern USA, our hospital serves a racially, ethnically and socio-economically diverse population. We collected data on patients' gender, race/ethnicity, insurance status, preferred spoken language, and distance to the hospital. SDoH was assessed using the Childhood Opportunity Index (COI) and the Social Vulnerability Index (SVI). COI is a validated tool used to estimate social determinants of health based on census tract. SVI is a validated Center for Disease Control mapping tool that identifies socially vulnerable communities based on socio-economic status, language proficiency, disability, housing, minoritized status, and transportation factors. Data on all infections leading to hospitalization, including the number and type, was collected. Chi-square tests (Pearson or Mantel-Haenszel) were used for association analysis and Wilcoxon Rank-Sum test was used to compare continuous variables in determining associations between the number of infections and the factors above. Patients were categorized into groups based on the number of infections during the study period: 0, 1-2, 3-4 or more than 5 infections.

The study population included patients with B or T cell ALL (74), AML or APML (18), or blastic plasmacytoid dendritic cell leukemia (1). Six patients had relapsed leukemia. Demographics were as follows: 50% female, 30% Black, 24.5% Hispanic, and 22.3% with non-English language preference; 69% of patients had public insurance, 5 were uninsured. 75% lived more than 70 miles from our hospital. Compared with national standards, 81% of patients had either very low (37, 39.4%) or low (40, 42.6%) COI score. Compared with state standards, 46% of patients had either very low (20, 21.3%) or low (24, 25.5%) COI score. 61.7% (58) of patients lived in areas with high SVI, indicating greater social vulnerability. 67% of patients were diagnosed with at least one infection requiring readmission or extending hospitalization; 28 patients had 1-2 infections, 22 had 3-4 infections, and 12 had 5 or more. While no single factor predicted an increased risk for infection, patients coming from areas of high SVI were more likely to be hospitalized for multiple infections (p = 0.0596). The overall survival rate of the group was 82%. Five patient deaths were attributed to infection related complications during the intensive chemotherapy period. No factor was associated with an increased risk for mortality.

Our findings suggest pediatric patients with acute leukemia coming from areas of high SVI,(indicating social vulnerability based on demographics, housing/transportation resources and socio-economic status), are hospitalized for more infections compared to patients from areas of low SVI. This increased risk may be explained by the cumulative effect of various SDoH and the complex interplay between each component, rather than any one factor alone. Our findings regarding the impact of SDoH on risk for infection-related hospitalizations may help illuminate the causes of broader disparities in pediatric acute leukemia outcomes. The high vulnerability of patients in Louisiana makes treating leukemia more difficult compared to regions without these challenges. This underscores the need for ongoing efforts to address vulnerabilities related to SDoH to improve oncological outcomes, especially in underserved regions like ours. Further studies are necessary to determine if these trends are consistent in states with higher COI and lower SVI.