Ethnic and socioeconomic disparities lead to differences in survival according to a large study of acute lymphoblastic leukaemia
Ethic and socioeconomic disparities in survival outcomes have been highlighted in an analysis of newly diagnosed children and young adults with acute lymphoblastic leukaemia (ALL). This was the main finding from a study by researchers from Institute for Health Policy, Evaluation and Management, University of Toronto, Canada, presented at ASH 2021.
Health disparities are major issue for racial, ethnic, and socioeconomically disadvantaged groups and although outcomes in childhood ALL have steadily improved, disparities based on ethnicity and socioeconomic (SES) factors appear to persist.
For the present study, the Canadian team sought to identify the presence of any persistent inequities by race/ethnicity and SES in childhood ALL in the largest cohort ever assembled for this purpose. They identified a cohort of newly-diagnosed patients with ALL, ranging in age from 0 to 40 years enrolled in trials between 2004-2019. Race/ethnicity was categorised as non-Hispanic white vs. Hispanic vs. non-Hispanic Black vs. non-Hispanic Asian vs. Non-Hispanic other.
SES was proxied by insurance status: United States (US) Medicaid (public health insurance for low-income individuals) vs. US other (predominantly private insurance) vs. non-US patients (mainly jurisdictions with universal health insurance). Event-free and overall survival (EFS, OS) were compared across race/ethnicity and SES. The relative contribution of disease prognosticators (age, sex, white blood cell count, lineage, central nervous system status, cytogenetics, end Induction minimal residual disease) were examined with Cox proportional hazard multivariable models of different combinations of the three constructs of interest (race/ethnicity, SES, disease prognosticators) and examining hazard ratio (HR) attenuation between models.
The study cohort included 24,979 children, adolescents, and young adults with ALL. A total of 13,872 (65.6%) of the whole cohort were Non-Hispanic White patients, followed by 4354 (20.6%) Hispanic patients and 1517 (7.2%) non-Hispanic Black patients. Those insured with US Medicaid were 6944 (27.8%).
The 5-year EFS was 87.4% among non-Hispanic White patients vs. 82.8% among Hispanic patients (hazard ratio, HR = 1.37, 95% CI 1.26 – 1.49; p<0.0001] and 81.9% among non-Hispanic Black patients. The outcomes for non-Hispanic Asian patients were similar to those of non-Hispanic White patients.
US patients on Medicaid had inferior 5-year EFS as compared to other US patients (83.2% vs. 86.3%, HR = 1.21, 95% CI 1.12 – 1.30, p<0.0001) while non-US patients had the best outcomes, with a 5-year EFS of 89%.
There was substantial imbalance in traditional disease prognosticators (e.g. T-cell lineage) across both race/ethnicity and SES, and of race/ethnicity by SES. For example, T-lineage ALL accounted for 17.6%, 9.4%, and 6.6% of Non-Hispanic Black, Non-Hispanic White, and Hispanic patients respectively (p<0.0001).
Multivariable analysis showed how EFS among Hispanic patients was substantially attenuated by the addition of disease prognosticators and the hazard ratio reduced from HR 1.37 to 1.17 and was further (but not fully) attenuated by the subsequent addition of SES (HR 1.11).
In contrast, the increased risk among non-Hispanic Black children was minimally attenuated by both the addition of disease prognosticators and subsequent addition of SES (HR reduction of 1.45 to 1.38 to 1.32). Similarly, while the superior EFS of non-US insured patients was substantially attenuated by the addition of race/ethnicity and disease prognosticators (HR 0.79 to 0.94), increased risk among US Medicaid patients was minimally attenuated by the addition of race/ethnicity or disease prognosticators (HR 1.21 to 1.16).
OS disparities followed similar patterns but were consistently worse than in EFS, particularly among patients grouped as non-Hispanic other.
The authors concluded that there were substantial disparities in survival outcomes by race/ethnicity and SES and that these disparities varied between specific disadvantaged groups., adding that future studies are required to identify specific drivers of survival disparities that may be mitigated by targeted interventions.
Gupta S et al. Racial, Ethnic, and Socioeconomic Factors Result in Disparities in Outcome Among Children with Acute Lymphoblastic Leukemia Not Fully Attenuated By Disease Prognosticators: A Children’s Oncology Group (COG) Study. ASH Conference 2021