Causal Mediation Analysis for Childhood Cancer Survival Disparity in Texas, 2005 to 2014

Abstract

This study aimed to examine the disparities of childhood cancer survival among different racial and ethnic groups in Texas. The analysis was mediated by socioeconomic status (SES) and spatial accessibility to Children Oncology Group (COG) hospitals. The relationship between race-ethnicity and overall survival was measured using the Cox proportional hazards model with a robust variance estimator. The counterfactual model measures the total effect of race-ethnicity on survival through all mediating pathways while adjusting for baseline confounders (age, sex, and stage at diagnosis), which are then decomposed into natural direct and indirect effects. Considering all cancer site groups, African Americans showed a statistically significant higher hazard ratio in death (HR = 3.63; 95% CI = 1.87 - 6.62) compared with non-Hispanic White children. At the same time, the mortality hazard ratio among Hispanic children is not significant (HR = 1.23; 95% CI = 0.80 - 1.93) when compared with non-Hispanic White children. Analysis results also suggested that both mediators significantly contribute to racial-ethnic survival disparities for specific cancer site groups such as Leukemia for African American children. This study builds knowledge and understanding about underlying factors (mediators) responsible for the disparities in the outcomes among childhood cancer patients.