In fiscal year 2016, Medicaid covered an estimated 72.2 million low- income and medically needy individuals in the United States, and Medicaid estimated expenditures totaled over $575.9 billion. The federal government matches most state expenditures for Medicaid services on the basis of a statutory formula. States receive higher federal matching rates for certain services or populations, including an enhanced matching rate for Medicaid expenditures for individuals who became eligible for Medicaid under PPACA. Of the $575.9 billion in estimated expenditures for 2016, the federal share totaled over $363.4 billion and the states’ share totaled $212.5 billion. The Centers for Medicare & Medicaid Services (CMS)—a federal agency within the Department of Health and Human Services (HHS)—and states jointly administer and fund the Medicaid program. States have flexibility within broad federal requirements to design and implement their Medicaid programs. States must submit a state Medicaid plan to CMS for review and approval. A state’s approved Medicaid plan outlines the services provided and the groups of individuals covered. While states must cover certain mandatory populations and benefits, they have the option of covering other categories of individuals and benefits. PPACA permitted states to expand coverage to a new population—non- elderly, non-pregnant adults who are not eligible for Medicare and whose income does not exceed 138 percent of the FPL. This expansion population comprised 20 percent of total Medicaid enrollment in 2017. (See fig. 1.) As of December 2017, 31 states and the District of Columbia had expanded Medicaid eligibility to the new coverage population allowed under PPACA and 19 states had not. Figure 2, an interactive map, illustrates states’ Medicaid expansion status. See appendix II for additional information on figure 2. According to the NHIS estimates, 5.6 million low-income adults were uninsured in 2016. Of these 5.6 million, an estimated 1.9 million uninsured, low-income adults resided in expansion states, compared with an estimated 3.7 million in non-expansion states. Estimates of uninsured, low-income adults comprised less than 1 percent of the total population for all expansion states and 3 percent of the total population for all non- expansion states. NHIS estimates also showed that over half of uninsured, low-income adults were male, over half were employed, and over half had incomes less than 100 percent FPL. For some demographic characteristics, there were some statistically significant differences between uninsured, low- income adults in expansion states compared with these adults in non- expansion states. For example, expansion states had significantly larger percentages of uninsured, low-income males than non-expansion states. (See table 1.) See table 6 in appendix III for additional demographic characteristics of uninsured, low-income adults. Estimates from the 2016 NHIS showed some statistically significant differences in the health status of uninsured, low-income adults in expansion and non-expansion states. In particular, expansion states had a larger percentage of these adults who reported that their health was “good” and a smaller percentage who reported their health as “fair or poor” than those in non-expansion states. However, the percentages of uninsured, low-income adults with responses of “excellent or very good” in both expansion and non-expansion states were large—47 percent or larger, and the differences between the two groups of states were not statistically significant. (See fig. 3.) See table 7 in appendix III for additional information about the health status for uninsured, low-income adults. The 2016 NHIS estimates showed that smaller percentages of low- income adults in expansion states reported having any unmet medical needs compared with those in non-expansion states; and smaller percentages of those who were insured reported having any unmet medical needs compared with those who were uninsured, regardless of where they lived, for example: Low-income adults in expansion and non-expansion states. Access to Health Care: Measuring Any Unmet Medical Needs The National Center for Health Statistics, the federal agency that conducts the National Health Interview Survey (NHIS), developed a composite measure on any unmet medical needs, which was based on six survey questions on respondents’ ability to afford different types of needed health care services. These questions asked whether in the past 12 months respondents could not afford medical care at any time; delayed seeking medical care due to worries about costs; or could not afford needed prescription drugs, mental health or counseling, dental care, or eyeglasses. percent or less of the low-income adults who had Medicaid or private health insurance in expansion or non-expansion states reported having any unmet medical needs, compared with 50 percent or more of those who were uninsured in expansion or non-expansion states. Further, among the uninsured, 50 percent of low-income adults living in expansion states reported any unmet medical needs, compared with 63 percent of those in non-expansion states. (See fig. 4.) See tables 8 and 9 in appendix IV for estimates of the composite measure we reviewed on any unmet medical needs. The 2016 NHIS estimates showed that smaller percentages of low- income adults in expansion states reported financial barriers to needed health care compared with those in non-expansion states; and smaller percentages of those who were insured reported financial barriers to needed health care compared with those who were uninsured, regardless of where they lived, for example: Low-income adults in expansion and non-expansion states. Nine percent of low-income adults in expansion states reported that they could not afford needed medical care, compared with 20 percent of low-income adults in non-expansion states. Low-income adults who were insured and uninsured. Twelve percent or less of low-income adults who had Medicaid or private health insurance in expansion or non-expansion states reported financial barriers to needed medical care, compared with 27 percent or more of those who were uninsured in expansion or non-expansion states. In addition, among low- income adults who were uninsured, a smaller percentage of those who lived in expansion states reported financial barriers to two of the six needed health care services compared with those who lived in non-expansion states. (See fig. 5.) See tables 10 through 13 in appendix V for estimates of all survey questions we reviewed on financial barriers to health care. The 2016 NHIS also collected information on non-financial barriers to health care. Specifically, the survey asked whether respondents had delayed health care due to non-financial reasons, such as they lacked transportation, were unable to get through on the phone, were unable to get a timely appointment, experienced long wait time at the doctor’s office, or were not able to get to a clinic or doctor’s office when it was open. The 2016 NHIS showed that the same or similar percentages of low-income adults in expansion and non-expansion states reported delaying care due to a lack of transportation or other non-financial reasons. Further, generally similar or larger percentages of low-income adults with insurance reported delaying care due to non-financial reasons, compared with those who were uninsured. See tables 14 and 15 in appendix V for estimates of low-income adults in expansion and non- expansion states and by insurance status on non-financial barriers to health care. The 2016 NHIS estimates showed that a larger percentage of low-income adults in expansion states reported having a usual place of care compared with those in non-expansion states; and larger percentages of those who were insured reported having a usual place of care compared with those who were uninsured, regardless of where they lived, for example: Low-income adults in expansion and non-expansion states. Eighty-two percent of the low-income adults in expansion states reported having a usual place of care when they were sick or needed advice about their health, compared with 68 percent of those in non- expansion states. Access to Health Care: Having a Usual Place of Care The 2016 National Health Interview Survey (NHIS) asked respondents about whether they had a place they usually go when sick or need advice about their health. Low-income adults who were insured and uninsured. Seventy- eight percent or more of those who had Medicaid or private health insurance in expansion or non-expansion states reported having a usual place of care, compared with 46 percent or less of those who were uninsured in expansion or non-expansion states. Among the uninsured, similar percentages of low-income adults in expansion and non-expansion states reported having a usual place of care. (See fig. 6.) See tables 16 through 19 in appendix VI for estimates of all survey questions we reviewed on having a usual place of care. The 2016 estimates showed that larger percentages of low-income adults in expansion states reported receiving selected health care services, such as a flu vaccine, compared with those in non-expansion states; and larger percentages of those with insurance reported receiving selected health care services compared with those who were uninsured, regardless of where they lived, for example: Low-income adults in expansion and non-expansion states. Thirty-one percent of low-income adults in expansion states reported receiving flu vaccinations, compared with 24 percent of those in non- expansion states. having their blood cholesterol checked by having their blood pressure checked by a doctor, nurse, or other health professional; visiting a hospital emergency department. percent or more of low-income adults who had Medicaid or private health insurance in expansion or non-expansion states reported receiving blood cholesterol checks, compared with 28 percent or less of low-income adults who were uninsured in expansion or non- expansion states. Among the uninsured, generally similar percentages of low-income adults in expansion and non-expansion states reported blood cholesterol checks, flu vaccines, and other selected services. (See fig. 7.) See tables 20 and 21 in appendix VI for estimates of all survey questions we reviewed on selected health care services. The 2016 NHIS also asked respondents whether they visited or had spoken to a health care professional about their health, including: a general doctor, such as a general practitioner, family doctor, and a nurse practitioner, physician’s assistant, or midwife; and a doctor who specializes in a particular disease, with the exception of obstetricians, gynecologists, psychiatrists, and ophthalmologists. See tables 22 and 23 in appendix VI for estimates of low-income adults in expansion and non-expansion states and by insurance status on contacting health care professionals. We provided a draft of this report to HHS for comment. HHS provided technical comments, which we incorporated as appropriate. As agreed with your offices, unless you publicly announce the contents of this report earlier, we plan no further distribution until 30 days from the report date. At that time, we will send copies of this report to the Secretary of Health and Human Services, the appropriate congressional committee, and other interested parties. In addition, this report is available at no charge on the GAO website at http://www.gao.gov. If you are your staff members have any questions about this report, please contact me at (202) 512-7114 or yocomc@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. Major contributors to this report are listed in appendix VII. To describe national survey estimates of (1) the number and demographic characteristics of uninsured, low-income adults in expansion and non-expansion states; (2) unmet medical needs for low-income adults in expansion and non-expansion states and by insurance status; (3) barriers to health care for low-income adults in expansion and non- expansion states and by insurance status; and (4) having a usual place of care and receiving selected health care services for low-income adults in expansion and non-expansion states and by insurance status, we used data from the 2016 National Health Interview Survey (NHIS). The 2016 NHIS were the most recent data available when we conducted our analyses. This appendix describes the data source, study population, analyses conducted, study limitations, and data reliability assessment. The NHIS collects demographic, health status, health insurance, health care access, and health care service use data for the civilian, noninstitutionalized U.S. population. It is an annual, nationally representative, cross-sectional household interview survey. NHIS interviews are conducted continuously throughout the year for the National Center for Health Statistics (NCHS), which is a federal agency within the Department of Health and Human Services that compiles statistical information to help guide health policy decisions. Interviews are conducted in respondents’ homes, and interviewers may conduct follow- up interviews over the telephone to complete an interview. Information about some NHIS respondents, such as information about their health status, may be obtained through an interview with another family member on behalf of the respondent. NHIS data are organized into several data files. Estimates used for our study are based on data with the 2016 Family and Sample Adult Core components of the 2016 NHIS. Sociodemographic, insurance, and select health care access and utilization variables were defined using data collected in the Family Core component of the survey, which includes data on every household member for the families participating in NHIS. Other measures of health care access and utilization examined in this study are based on data collected in the Sample Adult Core component. In this component, the respondent (i.e., the sample adult) is randomly selected from among all adults aged ≥18 years in the family. A proxy respondent might respond for the sample adult if, because of health reasons, the sample adult is physically or mentally unable to respond themselves. The 2016 imputed income files were used to define poverty thresholds, which is based on reported and imputed family income. The NHIS publicly released data files for 2016 include data for 40,220 households containing 97,169 persons, and the total household response rate was 67.9 percent. For this study we asked NCHS to provide estimates of low-income, non- elderly adults, which we defined as individuals ages 19 to 64, with family incomes that did not exceed 138 percent of the federal poverty level (FPL). We also requested that estimates be provided separately for respondents based on whether they resided in an expansion or non- expansion state, and whether they were covered by private health insurance, Medicaid, or had no insurance. We gave NCHS specifications for the definition of low-income, non-elderly adults; the states that should be classified as expansion or non-expansion states in calendar year 2016; and the respondents who should be classified as having private health insurance, Medicaid, or no insurance. We asked NCHS to exclude respondents who were noncitizens, were covered by Medicare, only received health care services through military health care or through the Indian Health Service, or had Supplemental Social Security Income. We also excluded adult females from the Sample Adult file who responded they were pregnant at the time of the interview. In addition, we asked NCHS to exclude individuals for which information was missing—not recorded or not provided during the interview—on health insurance coverage (Medicaid, private health insurance, Indian Health Service, military health care, or no health insurance), receipt of Supplemental Social Security Income, and U.S. citizenship. We classified individuals in our study population as residing in an expansion or non-expansion state based on their state of residence when they were interviewed for the 2016 NHIS. We classified the 30 states and the District of Columbia that expanded their Medicaid eligibility before July 1, 2016, as expansion states. The remaining 20 states were classified as non-expansion states. Louisiana expanded Medicaid coverage on July 1, 2016; therefore, we classified it as a non-expansion state. We decided not to classify Louisiana as an expansion state because we allowed a 6- month period for the effects of expansion to appear. Therefore, for Louisiana we only included NHIS respondents interviewed from January through June 2016 when Louisiana was a non-expansion state. Similarly, for two expansion states—Alaska and Montana—we only included individuals who were interviewed March through December 2016 and July through December 2016, respectively, after the state expanded Medicaid to allow for a 6-month time period for the effect of expansion to take place. (See table 2.) Table 3 below illustrates the sample size and population estimates of low- income sample adults by expansion state, non-expansion state, and national total. We classified NHIS respondents as having private health insurance, Medicaid, or no insurance based on the health insurance classification approach used by NCHS for NHIS. NCHS assigned NHIS respondents’ health insurance classification based on a hierarchy of mutually exclusive categories in the following order: private health insurance, Medicaid, other coverage, and uninsured. Low-income adults with more than one coverage type were assigned to the first appropriate category in the hierarchy. Respondents were classified as having private health insurance if they reported that they were covered by any comprehensive private health insurance plan (including health maintenance and preferred provider organizations). Private coverage excluded plans that pay for one type of service, such as accidents or dental care. Respondents were classified as having Medicaid if they reported they were covered by Medicaid or by a state-sponsored health plan with no premiums or it was not known whether a premium was charged. Respondents were classified as being uninsured if they did not report having any private health insurance, Medicare, Medicaid, Children’s Health Insurance Program, state-sponsored or other government-sponsored health plan, or military health plan. Respondents were also classified as being uninsured if they only had insurance coverage with a private plan that paid for one type of service, such as accidents or dental care. We gave NCHS officials specifications to calculate estimates from the 2016 NHIS for demographic characteristics, access to care, as well as composite measures of access to health care based on selected survey questions. Composite measures are NCHS-developed measures based on responses to NHIS questions covering related topics. The analysis included two composite measures: 1. any unmet medical needs, which is based on responses to six underlying survey questions that asked respondents about whether during the past 12 months they needed medical care but did not get it because they could not afford it; delayed seeking medical care because of worry about the cost; or did not get prescription medicines, mental health care or counseling, eyeglasses, or dental care due to cost; and 2. any non-financial barriers to health care, which is based on five underlying questions that asked respondents whether they delayed care in the past 12 months for any of the following reasons: could not get through on the telephone; could not get an appointment soon enough; waited too long to see the doctor after arriving at the doctor’s office; the clinic/doctor’s office was not open when respondent could get there; and did not have transportation. NCHS officials calculated our requested estimates of groups within our study population based on whether respondents resided in an expansion or non-expansion state and whether they had private health insurance, Medicaid, or were uninsured at the time of the interview. For each comparison—such as comparisons of access to health care for respondents in expansion versus non-expansion states—we asked NCHS to test for statistically significant differences. We identified a statistically significant difference when the p-value from a t-test of the difference in the estimated proportions between two study subgroups had a value of less than 0.05. To describe the number and demographic characteristics of uninsured, low-income adults, we compared estimates of selected demographic characteristics (race and ethnicity, gender, poverty status, and employment status) and reported health status for this group in expansion and non-expansion states. These and other estimates of demographic characteristics and reported health status from the 2016 NHIS for uninsured, low-income adults by expansion states, non-expansion states, and all states are provided in tables 6 and 7 in appendix III. To describe unmet medical needs, barriers to health care, and having a usual place of care and receiving selected services for all low-income adults in expansion and non-expansion states and by insurance status, we asked NCHS to calculate estimates based on responses to selected NHIS questions and NCHS composite measures. We selected these survey questions and composite measures from the Family and Adult Access to Health Care and Utilization and Adult Health Behaviors sections of the 2016 NHIS. To summarize estimates of low-income adults in expansion and non-expansion states and by insurance status, responses to selected survey questions and composite measures were calculated as an estimated percentage of the relevant group’s total population for eight groups of low-income adults: (1) those in expansion states, (2) those in non-expansion states, (3) those who had Medicaid in expansion states, (4) those who had Medicaid in non-expansion states, (5) those who had private health insurance in expansion states, (6) those who had private health insurance in non-expansion states, (7) those who were uninsured in expansion states, and (8) those who were uninsured in non-expansion states. We asked NCHS to test for statistically significant differences for the estimates of access to care between selected groups of low-income adults. (See table 4.) The results of the tests for statistically significant differences for these comparison groups are in appendixes IV through VI. Our study has some limitations. First, our study did not examine whether statistically significant differences in estimates of access to health care between respondents in expansion and non-expansion states were associated with the choice to expand Medicaid. Second, NHIS data are based on respondent-reported data, which may be subject to potential biases and recall of participants’ use of health services and may be less accurate than administrative data or clinical data. Third, we could not report estimates of access to health care that did not meet NCHS’s standards of reliability or precision. We assessed the reliability of NHIS data by reviewing NHIS data documentation; interviewing knowledgeable NCHS officials and academic researchers; and examining the data for logical errors, missing values, and values outside of expected ranges. We determined that the data were sufficiently reliable for the purposes of these analyses. Under the Patient Protection and Affordable Care Act (PPACA), states may opt to expand their Medicaid programs’ eligibility to cover certain low-income adults beginning January 2014. As of December 2017, 31 states and the District of Columbia had expanded their Medicaid programs as permitted under PPACA and 19 states had not. Table 5 lists the states that expanded Medicaid eligibility and those that did not. It also includes state population and other Medicaid data, which is presented in the roll-over information in interactive figure 2. This appendix provides additional 2016 National Health Interview Survey (NHIS) estimates we obtained from the National Center for Health Statistics (NCHS). Table 6 presents estimates of selected demographic characteristics for low-income adults who were uninsured at the time of the survey interview. The table provides estimates for these adults based on whether they resided in states that expanded Medicaid eligibility as permitted under the Patient Protection and Affordable Care Act (PPACA) (referred to as expansion states) or states that did not (referred to as non- expansion states). We report statistically significant differences when comparing the responses of uninsured, low-income adults in expansion and non-expansion states. Table 7 shows estimates of the reported health status of uninsured, low- income adults based on whether they resided in an expansion or non- expansion state. The table provides the number and percent of these adults who reported that at the time of the interview their health status was excellent or very good; good; or fair or poor. The table also shows the extent to which these adults reported whether their health status was different at the time of the interview compared to the previous year. We report statistically significant differences when comparing the responses of uninsured, low-income adults in expansion and non-expansion states. This appendix provides estimates of any unmet medical needs for low- income adults—individuals ages 19 to 64, with family incomes that did not exceed 138 percent of the federal poverty level (FPL)—from the 2016 National Health Interview Survey (NHIS), which were produced by the National Center for Health Statistics (NCHS). Estimates are based on a composite measure of any unmet medical needs. Table 8 shows estimates of all low-income adults in expansion and non-expansion states. We also report statistically significant differences between low- income adults in expansion and non-expansion states. Table 9 shows estimates of six groups of low-income adults: (1) low- income adults who were uninsured in expansion states; (2) low-income adults who were uninsured in non-expansion states; (3) low-income adults who had Medicaid in expansion states; (4) low-income adults who had Medicaid in non-expansion states; (5) low-income adults who had private health insurance in expansion states; and (6) low-income adults who had private health insurance in non-expansion states. We also report any statistically significant differences when comparing the six groups of low-income adults, specifically: low-income adults who were uninsured in expansion states compared with each of the four groups of low-income adults who were insured— low-income adults who had Medicaid in expansion states, low-income adults who had Medicaid in non-expansion states, low-income adults who had private health insurance in expansion states, and low-income adults who had private insurance in non-expansion states; low-income adults who were uninsured in non-expansion states compared with each of the four groups of low-income adults who were insured; low-income adults who were uninsured in expansion states compared with low-income adults who were uninsured in non-expansion states; low-income adults who had Medicaid in expansion states compared with low-income adults who had Medicaid in non-expansion states; and low-income adults who had private health insurance in expansion states compared with low-income adults who had private health insurance in non-expansion states. This appendix provides estimates of barriers to health care for low- income adults—individuals ages 19 to 64, with family incomes that did not exceed 138 percent of the federal poverty level (FPL)—from the 2016 National Health Interview Survey (NHIS), which we obtained from the National Center for Health Statistics (NCHS). Estimates of financial barriers to needed medical, specialty, and other types of health care and prescription drugs are based on selected survey questions. Estimates of non-financial barriers to health care are based on responses to selected survey questions and a composite measure. Estimates are reported for: All low-income adults in expansion and non-expansion states. We also report statistically significant differences between low-income adults in expansion and non-expansion states. Six groups of low-income adults: (1) low-income adults who were uninsured in expansion states; (2) low-income adults who were uninsured in non-expansion states; (3) low-income adults who had Medicaid in expansion states; (4) low-income adults who had Medicaid in non-expansion states; (5) low-income adults who had private health insurance in expansion states; and (6) low-income adults who had private health insurance in non-expansion states. We also report any statistically significant differences when comparing the six groups of low-income adults, specifically: low-income adults who were uninsured in expansion states compared with each of the four groups of low-income adults who were insured—low-income adults who had Medicaid in expansion states, low-income adults who had Medicaid in non-expansion states, low-income adults who had private health insurance in expansion states, and low-income adults who had private insurance in non-expansion states; low-income adults who were uninsured in non-expansion states compared with each of the four groups of low-income adults who were insured; low-income adults who were uninsured in expansion states compared with low-income adults who were uninsured in non- expansion states; low-income adults who had Medicaid in expansion states compared with low-income adults who had Medicaid in non- expansion states; and low-income adults who had private health insurance in expansion states compared with low-income adults who had private health insurance in non-expansion states. Financial barriers to medical, specialty, and other types of health care. Tables 10 and 11 present estimates and differences in estimates of responses to survey question that asked whether respondents did not obtain different types of needed health care services in the past 12 months because they could not afford it. Financial barriers to prescription drugs. Tables 12 and 13 present estimates and differences in estimates of survey question that asked respondents who had been prescribed medications whether they had taken actions during the past 12 months to save money on medications. Non-financial barriers to health care. Tables 14 and 15 present estimates and differences in estimates of the NCHS composite measure on any non-financial barriers to health care, which was based on responses to five survey questions on whether respondents delayed care in the past 12 months due to long wait times, a lack of transportation, and other non-financial reasons. Additionally, these tables present estimates and differences in estimates of responses to the composite measure’s five underlying survey questions. This appendix provides estimates on having a usual place of care and receiving selected health care services for adults—individuals ages 19 to 64, with family incomes that did not exceed 138 percent of the federal poverty level (FPL)—from the 2016 National Health Interview Survey (NHIS), which we obtained from the National Center for Health Statistics (NCHS). Estimates are based on responses to selected survey questions on having a usual place of care, receiving selected health care services, and contacting health care professionals. Estimates are reported for: All low-income adults in expansion and non-expansion states. We also report statistically significant differences between low-income adults in expansion and non-expansion states. Six groups of low-income adults: (1) low-income adults who were uninsured in expansion states; (2) low-income adults who were uninsured in non-expansion states; (3) low-income adults who had Medicaid in expansion states; (4) low-income adults who had Medicaid in non-expansion states; (5) low-income adults who had private health insurance in expansion states; and (6) low-income adults who had private health insurance in non-expansion states. We also report any statistically significant differences when comparing the six groups of low-income adults, specifically: low-income adults who were uninsured in expansion states compared with each of the four groups of low-income adults who were insured—low-income adults who had Medicaid in expansion states, low-income adults who had Medicaid in non-expansion states, low-income adults who had private health insurance in expansion states, and low-income adults who had private insurance in non-expansion states; low-income adults who were uninsured in non-expansion states compared with each of the four groups of low-income adults who were insured; low-income adults who were uninsured in expansion states compared with low-income adults who were uninsured in non- expansion states; low-income adults who had Medicaid in expansion states compared with low-income adults who had Medicaid in non- expansion states; and low-income adults who had private health insurance in expansion states compared with low-income adults who had private health insurance in non-expansion states. Having a usual place of care. Tables 16 through 19 present estimates and differences in estimates of survey questions that asked respondents about the place of care they usually go to when sick or need advice about their health and the type of place that respondents most often went. Receiving selected health care services. Tables 20 and 21 present estimates and differences in estimates of survey questions that asked respondents whether they had received a blood cholesterol check, flu vaccine, or other selected services. Contacting health care professionals. Tables 22 and 23 present estimates and differences in estimates of survey questions that asked respondents whether they had visited or spoken to a general doctor, specialist, or other health care professionals about their health in the past 12 months. In addition to the contact named above, Katherine M. Iritani (Director), Tim Bushfield (Assistant Director), Deitra H. Lee (Analyst-in-Charge), Kristin Ekelund, Laurie Pachter, Vikki Porter, Merrile Sing, and Emily Wilson made key contributions to this report.

Summary: Under PPACA, states could choose to expand Medicaid coverage to certain uninsured, low-income adults. As of December 2017, 31 states and the District of Columbia chose to expand Medicaid to cover these adults, and 19 states did not. GAO was asked to provide information about the demographic characteristics of and access to health care services for low-income adults—those with household incomes less than or equal to 138 percent of the federal poverty level—in expansion and non-expansion states. This report describes 2016 national survey estimates of (1) the number and demographic characteristics for low-income adults who were uninsured in expansion and non-expansion states, (2) unmet medical needs for low-income adults in expansion and non-expansion states and by insurance status, (3) barriers to health care for low-income adults in expansion and non-expansion states and by insurance status, and (4) having a usual place of care and receiving selected health care services for low-income adults in expansion and non-expansion states and by insurance status. GAO obtained 2016 NHIS estimates from the National Center for Health Statistics (NCHS), the federal agency within the Department of Health and Human Services that maintains these survey data. NHIS is a household interview survey designed to be a nationally representative sample of the civilian, non-institutionalized population residing in the United States. Estimates were calculated for demographic characteristics for uninsured, low-income adults. In addition, estimates were calculated for unmet medical needs, barriers to health care, and having a usual place of care and receiving selected health services for low-income adults in expansion and non-expansion states and by insurance status The estimates were based on responses to selected survey questions. GAO selected these survey questions from the Family and Adult Access to Health Care and Utilization and another section of the 2016 NHIS. GAO took steps to assess the reliability of the 2016 NHIS estimates, including interviewing NCHS officials and examining the data for logical errors. GAO determined that the data were sufficiently reliable for the purposes of its analyses. The Department of Health and Human Services provided technical comments on a draft of this report, which GAO incorporated as appropriate. According to the 2016 National Health Interview Survey (NHIS), an estimated 5.6 million uninsured, low-income adults—those ages 19 through 64—had incomes at or below the income threshold for expanded Medicaid eligibility as allowed under the Patient Protection and Affordable Care Act (PPACA). Estimates from this nationally representative survey showed that about 1.9 million of the 5.6 million uninsured, low-income adults lived in states that chose to expand Medicaid under PPACA, while the remaining 3.7 million lived in non-expansion states—those that did not choose to expand Medicaid. In 2016, over half of uninsured, low-income adults were male, over half were employed, and over half had incomes less than 100 percent of the federal poverty level in both expansion and non-expansion states. The 2016 NHIS estimates showed that low-income adults in expansion states were less likely to report having any unmet medical needs compared with those in non-expansion states, and low-income adults who were insured were less likely to report having unmet medical needs compared with those who were uninsured. Among the low-income adults who were uninsured, those in expansion states were less likely to report having any unmet medical needs compared with those in non-expansion states. The 2016 NHIS estimates also showed that low-income adults in expansion states were less likely to report financial barriers to needed medical care and other types of health care, such as specialty care, compared with those in non-expansion states, and low-income adults who were insured were less likely to report financial barriers to needed medical care compared with those who were uninsured. Among low-income adults who were uninsured, those in expansion states were less likely to report financial barriers to needed medical care compared with those in non-expansion states. Finally, the 2016 NHIS estimates showed that low-income adults in expansion states were more likely to report having a usual place of care to go when sick or needing advice about their health and receiving selected health care services compared with those in non-expansion states. The estimates also showed that low-income adults who were insured were generally more likely to report having a usual place of care and receiving selected health care services compared with those who were uninsured. Among the uninsured, relatively similar percentages of low-income adults in expansion and non-expansion states reported having a usual place of care. Similarly, estimates showed that relatively similar percentages of low-income adults who were uninsured in expansion and non-expansion states reported receiving selected health care services, such as receiving a flu vaccine or a blood pressure check.