2C-06 - Analyzing Incidence of Adverse Events Commonly Assessed in Vaccine Safety Studies in Medicaid versus Commercially-Insured Populations in Carelon Research’s OMOP Data

Background: The FDA's Biologics Effectiveness and Safety (BEST) Initiative aims to enhance the post-market surveillance of biologics and vaccines by leveraging healthcare data sources. In 2023, BEST advanced efforts to add Medicaid data to its analyses. Medicaid provides healthcare coverage to millions of low-income people. By incorporating Carelon Research’s Medicaid data, BEST would introduce added variability, which can contribute to a more comprehensive understanding of safety and effectiveness of CBER-regulated products across patient populations.

Objectives: We aimed to assess the similarities and differences in background incidence between Carelon Research's Medicaid and commercial populations for adverse events commonly assessed in vaccine safety studies.

Methods: We calculated background rates using the commercial (COM) and Medicaid (MDCD) data in Carelon Research’s Observational Medical Outcomes Partnership (OMOP) extraction from the Healthcare Integrated Research Database for the 2023 calendar year. We calculated incidence Rates (IRs) per 100,000 person-years across age groups ( < 18 and 18-64) and report them as MDCD vs COM. Incident rate ratios (IRRs) compare MDCD to COM rates. 95% confidence intervals are omitted due to their negligible range.

Results: The MDCD population (N=5.1M) had a higher percentage of female members (54% vs. 50%) and more members under 18 (46% vs 20%) compared to the COM population (N=26.7M). Among adults, the most common events of interest included deep vein thrombosis (IR=265 MDCD vs 247 COM), atrial fibrillation (195 vs 208), and acute myocardial infarction (195 vs 137). Incidence rates were higher in the MDCD population for: acute myocardial infarction (IRR=1.42), disseminated intravascular coagulation (1.38), and non-hemorrhagic stroke (1.61). In children, febrile seizures (IR=521 vs 363), appendicitis (133 vs 115), and anaphylaxis (28 vs 35) were the most common events of interest, with acute myocardial infarction (IRR = 2.15) and myocarditis (1.60), chronic inflammatory demyelinating polyneuropathy (0.50), and Guillain-Barré Syndrome (0.62) having differences by population.

Conclusions: The Medicaid population has different health needs and event rates from the commercially-insured population. This increased heterogeneity is crucial for understanding the full range of risk factors, reinforcing the need to address differences within and between populations. By including Medicaid data, we move towards more comprehensive and nationally representative analyses.