Role of Social Determinants of Health on Infection-Related Hospitalizations in Pediatric Hematopoietic Stem Cell Transplant Patients within the First 100 Days Post-Transplant in an Underserved State
Authors: Brantley Alexis , Gillespie Nali , Viviano Morgan , Smith Leah , Feng Zhide , Velez-Yanguas Maria C. , LeBlanc Zachary 
Published: December 2024

Outcomes and survival in pediatric hematopoietic stem cell transplant (SCT) are primarily determined by diagnosis, conditioning regimen, and graft-vs-host disease (GVHD). Prior studies suggest that outcomes may also vary by race and socioeconomic status, though the underlying causes of these disparities remain unclear. One significant cause of morbidity and mortality in SCT is infection. We hypothesized that vulnerabilities related to social determinants of health (SDoH) would correlate with an increased likelihood of extended hospitalization or readmission due to infection within the first 100 days post-SCT.

Following IRB exempt status approval, we conducted a retrospective chart review of 64 patients undergoing SCT at a tertiary care pediatric hospital in Louisiana, an underserved Southern state, from 2017 to 2024. This hospital serves a racially, ethnically and socio-economically diverse population. We abstracted the following data: patient's gender, race and ethnicity, insurance status, preferred language, and distance to our hospital. SDoH were assessed using Childhood Opportunity Index (COI) and the Social Vulnerability Index (SVI). COI is a validated tool used to estimate SDoH 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 preference, disability, housing, minoritized status, and transportation factors. We also gathered data on infections leading to readmissions or extending existing hospital stays, including the number and type of infections. Statistical analysis was conducted using Chi-square tests (Pearson or Mantel-Haenszel).

Study population demographics were as follows: 42% female, 46.9% Black, 7.8% Hispanic, 7.8% with non-English language preference. 73.4% of patients were publicly insured. 50% lived more than 50 miles from the hospital, with a mean distance of 91 miles. Patients were treated with either autologous (16) or allogeneic (46) SCTs; 58.3% were treated for malignancy. Of the 46 patients with allogeneic HSCTs not receiving matched related donors, they received matched unrelated (21), mismatched unrelated (10), or haploidentical related (11) donors. Among all patients with allogenic SCT, 36.1% developed acute GVHD, with 30.7% of those cases being Grade III or IV. Compared with national standards, 78.2% of patients had either a very low (20, 31.3%) or low (30, 46.9%) COI score. Compared with state standards, 42.2% of patients had either very low (12, 18.8%) or low (15, 23.4%) COI score. 65.6% (42) of patients lived in areas of high SVI score, indicating greater social vulnerability. Overall, 50% of patients experienced at least one infection, with varying severity from respiratory illness to fungemia. No SDoH factor predicted an increased risk for infection with multivariate analysis (all p &gt; 0.05). The overall survival for patients receiving allogenic transplants was 72%, with eight deaths related to infection, four to disease recurrence, and one to GVHD. For autologous transplant patients, the survival rate was 75%, with all deaths due to disease recurrence. A weak association was found between lower COI (state level) and death (p = 0.0776), but no SDoH factor significantly impacted survival (all p &gt; 0.05).

Our study demonstrates that within a vulnerable population, no SDoH factor significantly increased risk for infection related hospitalization in the initial 100 days post-SCT. While there is likely a complex interplay between SDoH and outcomes in SCT, differential risk of infections in the initial post-transplant period may not be a key player in SCT outcome disparities. Because our hospital serves an especially vulnerable and diverse population, a higher proportion of high-risk SCTs was required. Despite the high-risk nature of these transplants, GVHD and survival outcomes are comparable to those reported in existing literature. The diversity of this cohort, coupled with a skew towards low opportunity and high social vulnerability, underscores the complexity of isolating single factors contributing to infection or survival outcomes. To assess the broader impact of SDoH on infection risk, additional research is needed comparing infection hospitalization risk in areas of low social vulnerability/high opportunity indices, and if differences emerge in infection risk beyond the 100-day post-transplant period.