There is growing evidence that the Affordable Care Act (ACA) has helped to reduce the number of uninsured adults, particularly in States that implemented the ACA’s Medicaid expansions. Research has also begun to show how the ACA’s changes in coverage are altering the way U.S. health care is financed. In a recent Health Affairs article, for example, Sayeh Nikpay and coauthors use data from the Agency for Healthcare Research and Quality (AHRQ) Hospital Cost and Utilization Project (HCUP) to show declines in the share of hospitalizations that are uninsured, and increases in the Medicaid share, in states that expanded Medicaid.

A Changing Coverage Mix For Ambulatory Care

Now, findings we published this week in an AHRQ statistical brief offer new insights into the changes that have occurred in the coverage mix of ambulatory care.
Our study examined ambulatory visits, including physician and emergency department visits, among adults ages 19 to 64 in AHRQ’s Medical Expenditure Panel Survey (MEPS) (Note 1). We examined the insurance coverage of visits in 2011-13 (prior to the main ACA coverage expansions) and then in 2014, presenting results separately for States that did and did not expand Medicaid coverage. Visit coverage was measured based on insurance held during the month the visit occurred. Because Marketplace enrollment continued into Spring 2014, our analysis examined the coverage of visits in the latter half of 2014 (comparing these visits to those from the latter halves of the prior years). Additional methodological details are available in the statistical brief.
As shown in Figure 1, the share of office and outpatient physician visits by adults who were uninsured declined substantially in Medicaid expansion states, from 8.4 percent in 2011-13 to 5.6 percent in 2014. Corresponding to this decrease, the share of visits with public coverage was 16.7 percent in 2014, compared to 13.4 percent in 2011-13. Meanwhile, in states that did not expand Medicaid, changes in visit shares were much smaller — and not statistically significant except for the case of Marketplace coverage. And, as of 2014, people who had obtained private coverage through the ACA Marketplace accounted for a relatively small share of physician visits.
Similar dynamics emerged regarding emergency department care. As shown in Figure 2, in States that expanded Medicaid, the share of emergency room visits by uninsured individuals declined from 19.8 percent in 2011-13 to 10.5 percent in 2014. The public coverage share in those States rose from 22.2 percent in 2011-13 to 34.8 percent in 2014. Once again, we did not observe similar changes in non-expansion States.

Growing Evidence

Our emergency room visit results provide nationally representative evidence broadly consistent with results from AHRQ’s Fast Stats online tool, using emergency room data from selected early-reporting states in the HCUP State Emergency Department Database and from a Health Affairs article by Jesse Pines and coauthors, using emergency department staffing company records. Our results are also consistent with a survey showing that many primary care clinicians are treating more people with Medicaid or who are newly insured, as well as evidence of a shift from uninsured to private coverage among young adults who visited emergency departments following the ACA’s dependent care expansion.
The size of the changes we observe in the coverage mix of care may reflect a number of factors — not only the reduction in the uninsured share of the population, but also the health risks of those who self-selected into coverage, their health care seeking behaviors, and availability of provider capacity. Analyzing the contributions of these factors is a subject for future research.

Figure 1


Figure 2

Source: Selden, T.M., Abdus, S., and Keenan, P.S. Insurance Coverage of Ambulatory Care Visits in the Last Six Months of 2011-13 and 2014, by Medicaid Expansion Status. Statistical Brief #494. October, 2016. Agency for Healthcare Research and Quality, Rockville, MD.

Note 1

AHRQ’s MEPS is a family of three surveys. The Household Component (HC) is the core survey and also forms the basis for the Medical Provider Component (MPC). Together these two surveys yield comprehensive data that provide national estimates of the level and distribution of health care use and expenditures in the civilian non-institutionalized population. The third survey, the Insurance Component (IC), is a survey of private and public sector employers that provides national- and state-level estimates of employer-sponsored health insurance coverage and cost. MEPS is the only national data source measuring how Americans use and pay for health insurance and medical care, as well as providing data on health status, access to care, and satisfaction with care. Statistical briefs, research findings, and other publications from all three MEPS surveys can be found here.

Authors’ Note

We appreciate the helpful comments of Joel Cohen and Bruce Seeman. The views expressed in this blog post are those of the authors, and no official endorsement by the Department of Health and Human Services or AHRQ is intended or should be inferred.