Insights into the Fragmented US Health System through Simulation Modeling: Childhood Insurance, Care Utilization, and Outcomes

Abstract

Empirical analyses of insurance, care utilization, and health outcomes are often constrained by fragmented health administrative data and limited follow-up in national surveys, yielding only a partial view of how these outcomes may change over longer time horizons. In this dissertation, I develop microsimulation modeling approaches to estimate the cumulative consequences of the fragmented US health system across the full course of childhood. Chapter 1 examines health insurance coverage; the remaining chapters expand this focus to routine care utilization (Chapter 2) and dental caries outcomes (Chapter 3), highlighting the implications of insurance fragmentation and the medical-dental divide. Chapter 1 estimates the cumulative health insurance experiences over childhood under post-Affordable Care Act (ACA), pre-pandemic policy conditions. The insurance landscape in the United States is fragmented across public and private options with substantial state variation. Using natality records and longitudinal national surveys including the Survey of Income and Program Participation (SIPP) and the Medical Expenditure Panel Survey (MEPS), I create a nationally representative synthetic cohort and develop nonparametric matching algorithms to simulate individual-level trajectories from birth until 18th birthday across five health insurance types: 1) Medicaid or Children’s Health Insurance Program (CHIP); 2) uninsured; 3) employment-based private; 4) Marketplace; and 5) other. Under the assumed policy conditions, I estimate that 61% of US children are ever enrolled in Medicaid or CHIP and 42% are ever uninsured by age 18. Among children born in Medicaid or CHIP, 36% experience any insurance loss in Medicaid adult expansion states compared with 59% in non-expansion states. These findings demonstrate the broad reach of Medicaid and CHIP, the common experience of coverage gaps, and substantial state-level variation by Medicaid policy restrictiveness over childhood. Chapter 2 investigates joint patterns of pediatric routine care utilization across primary care and dental settings and quantifies the impact on care continuity in two medical-dental integration scenarios under perfect implementation: 1) delivering dental services in primary care; 2) delivering primary care services in dental care. Using longitudinal MEPS data, I develop nonparametric matching algorithms to simulate individual-level trajectories of dental insurance coverage, primary care well-child visits, and routine dental visits for the synthetic cohort described in Chapter 1. Relative to recommended routine care schedules in each setting, I estimate that US children accumulate a mean of 11 years of unmet dental needs and 6 years of unmet primary care needs over childhood. Under perfect implementation, medical-dental integration could improve continuity of services in all insurance groups but does not fully eliminate unmet needs. Furthermore, the greatest gains accrue to insurance groups with the lowest unmet needs. Chapter 3 estimates cumulative dental caries outcomes and examines disparities by childhood insurance experience. As children’s dentition evolves through primary tooth eruption, shedding, and permanent tooth emergence, tooth surfaces become susceptible to dental caries, the most common chronic disease of childhood in the United States. Leveraging longitudinal electronic dental records and cross-sectional National Health and Nutrition Examination Survey (NHANES) data, I develop, calibrate, and validate a dental caries microsimulation model that incorporates dentition changes, insurance dynamics, and dental utilization (routine and symptom-driven) for the synthetic cohort described in Chapters 1 and 2. I estimate that 72% of US children develop any caries (primary or permanent) by their 18th birthday, with an average of 5.5 affected tooth surfaces. Children with high health insurance gaps (>10% of childhood) and those insured with >75% Medicaid/CHIP experience the highest cumulative burden of caries, whereas those insured with >75% employment-based health & dental coverage have the lowest. Although primary caries is more common, disparities by childhood insurance experience are more pronounced for permanent caries.