Medicaid Expansion and Outcomes among Adults

There are 60 million Americans covered by Medicaid and, when the Medicaid provision of the Patient Protection and Affordable Care Act (ACA) is implemented in 2014, millions more will be eligible to enroll. The Supreme Court of the United States has ruled that states will be entitled to choose whether to expand their Medicaid programs under the ACA; some states, particularly those facing budget pressures, are considering cutting back on Medicaid rather than expanding it.

Over the past decades, several states have expanded their Medicaid programs and studies have shown that expansions in the 1980s reduced mortality among infants and children. Nonetheless, data on the effect of Medicaid expansions among adults are scarce. There have been observational studies that have shown an association between Medicaid coverage and adverse outcomes among adults. However, according to researchers, those studies involved “unmeasured confounders that make Medicaid patients sicker than others.”

Medicaid has traditionally covered only low-income children, parents, pregnant women, and disabled individuals. The Medicaid expansion added nondisabled adults without dependent children (childless adults); this group is similar to the population that will gain eligibility under the ACA (all adults with incomes <138% of the federal poverty level).

Hypothesizing that Medicaid expansions would reduce mortality rates, rates of insurance, and cost-related barriers to care, and would improve self-reported health, particularly among minority and lower-income populations, researchers recently conducted a study to examine the effects of Medicaid expansions on mortality and other health-related outcomes among adults. They reported results online in the New England Journal of Medicine [doi:10.1056/NEJMsa1202099].

The study was a differences-in-differences quasi-experimental design that incorporated data before and after Medicaid expansions in expansion states and the control states. The researchers identified states that had implemented Medicaid expansions to cover childless adults 19 to 64 years of age between 2000 and 2005. The states that met the criteria were Arizona (expanded eligibility to childless adults living below 100% of the poverty level in November 2001 and to parents with incomes up to 200% in October 2002); Maine (expanded eligibility to childless adults with incomes up to 100% of the poverty level in 2002); and New York (expanded eligibility to childless adults with incomes up to 100% and parents with incomes up to 150% of the poverty level in 2001). The 3 states were compared with neighboring states without expansions (New Mexico for Arizona, New Hampshire for Maine, and Pennsylvania for New York).

The primary outcome was annual county-level all-cause mortality per 100,000 adults between 20 and 64 years of age. Secondary outcomes were rates of insurance, delayed care because of costs, and self-reported health.

Baseline mortality was 320 deaths per 100,000 adults in expansion states and 344 per 100,000 in control states. More than 80% of deaths were from internal causes.

Expansions in Medicaid were associated with a significant reduction in adjusted all-cause mortality (by 19.6 deaths per 100,000, for a relative reduction of 6.1%; P=.001). Reductions in mortality were greatest in older adults, nonwhites, and residents of poorer counties. Medicaid coverage was increased by 2.2 percentage points in expansion states (relative increase, 24.7%; P=.01) and rates of uninsurance decreased by 3.2 percentage points (relative reduction, 14.7%; P<.001).

Rates of care delayed because of costs decreased by 2.9 percentage points (relative reduction, 21.3%; P=.002), and the rates of self-reported health status as excellent or very good increased by 2.2 percentage points (relative increase, 3.4%; P=.04).

“State Medicaid expansions to cover low-income adults were significantly associated with reduced mortality as well as improved coverage, access to care, and self-reported health," the report concluded.