Abstract C102: Access and outcome disparities in immunotherapy: A comparative analysis of Medicaid vs. Private insurance using linked Johns Hopkins EHR and claims data

Abstract Background: Immune checkpoint inhibitors (ICIs) have improved outcomes in advanced cancers such as lung cancer and melanoma by enabling immune targeting of tumor cells. Despite clinical gains, ICIs are costly and can cause immune-related adverse events (irAEs) across organ systems. Medicaid patients often experience advanced-stage diagnoses and worse outcomes, but disparities in ICI use and irAEs by insurance and race remain poorly understood due to limited data and the novelty of these therapies. This study aimed to (1) compare ICI receipt and time to initiation by insurance type and (2) assess racial differences in irAEs and healthcare utilization. Methods: We used linked Johns Hopkins Health Plan (JHHP) claims and Johns Hopkins Medicine (JHM) EHR data (2017–2021) for adults with one of six cancers approved for ICIs (NSCLC, melanoma, renal, bladder, hepatocellular, head/neck). Patients had ≥1-month post-diagnosis enrollment and ≥2 claims ≥30 days apart. ICI receipt was identified via procedure/NDC codes. Severe irAEs were defined using diagnostic codes and systemic steroid use. Covariates included demographics (age, sex, race, insurance), clinical (cancer type, comorbidity, chemo/radiation), area deprivation index, and healthcare utilization. Aim 1 outcomes: ICI receipt (yes/no), time to initiation, 12-month costs, hospitalizations, and ED visits by insurance type. Aim 2 outcomes: Severe irAE occurrence, 12-month post-ICI costs and utilization by race. Multivariable logistic regressions and Cox models were used for binary and time-to-event outcomes. Healthcare costs were modeled using gamma-distributed GLMs with log link. Results: Among 2,800 patients, 598 were privately insured (EHP) and 2,202 had Medicaid (PP). ICI use was lower in EHP (6.9%) vs. PP (10.8%) with longer delays (mean 523 vs. 288 days; p<0.001). Female sex, EHP coverage, and greater comorbidity were associated with lower ICI use. NSCLC, radiation, and chemotherapy were linked with higher odds. Race was not significantly associated with ICI use or timing. ICI use was associated with higher ED visits and total costs. Severe irAEs were more frequent in males, PP patients, and those with earlier ICI initiation. irAEs strongly predicted ED visits (OR >3). Black patients had lower odds of severe irAEs but were over twice as likely to visit the ED after irAEs compared to White patients (p=0.021), indicating possible disparities in symptom management or outpatient access. Conclusions: ICIs were more frequently used and initiated earlier among Medicaid patients than privately insured patients, potentially reflecting differences in cancer severity or care patterns. Females and those with comorbidities had lower access. ICI use increased acute care burden, with irAEs driving ED use and costs. Despite fewer severe irAEs among Black patients, higher post-irAE ED use suggests disparities in symptom recognition or outpatient care. These findings highlight the need for equitable ICI access, proactive irAE monitoring, and integrated care pathways to reduce acute care utilization and costs. Citation Format: Chintan Pandya, Talan Zhang, Tom Richards, Kala Visvanathan. Access and outcome disparities in immunotherapy: A comparative analysis of Medicaid vs. Private insurance using linked Johns Hopkins EHR and claims data [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr C102.