This cohort study investigates whether rates of uninsurance among patients hospitalized for acute myocardial infarction (AMI) and in-hospital care and outcomes changed 3 years after states elected to expand Medicaid compared with nonexpansion states.
Key Points
Question
Among adults hospitalized for acute myocardial infarction, did uninsured rates, quality of care, and outcomes change in states that expanded Medicaid under the Patient Protection and Affordable Care Act compared with nonexpansion states?
Findings
This cohort study of 325 343 patients who had been hospitalized for acute myocardial infarction found that state Medicaid expansion was associated with a significant reduction in rates of uninsurance among patients hospitalized for acute myocardial infarction. Among low-income patients, there was no improvement in in-hospital quality of care or mortality compared with nonexpansion states.
Meaning
Three years after Medicaid expansion, states have experienced substantial declines in uninsured acute myocardial infarction hospitalizations, which has important implications regarding the financial protection of low-income patients; hospital care for acute myocardial infarction may be less sensitive to insurance than has been recognized in the past.
Abstract
Importance
Lack of insurance is associated with worse care and outcomes among adults hospitalized for acute myocardial infarction (AMI). It is unclear whether states’ decision to expand Medicaid eligibility under the Patient Protection and Affordable Care Act in 2014 were associated with improved quality of care and outcomes among low-income patients hospitalized with AMI.
Objective
To investigate whether rates of uninsurance, quality of care, and outcomes changed among patients hospitalized for AMI 3 years after states elected to expand Medicaid compared with nonexpansion states.
Design, Setting, and Participants
Retrospective cohort study completed at hospitals participating in National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network Registry. Participants were patients younger than 65 years hospitalized for AMI from January 1, 2012, to December 31, 2016.
Exposures
State Medicaid expansion in 2014.
Main Outcomes and Measures
Rates of uninsured and Medicaid-insured hospitalizations for AMI in states that expanded Medicaid vs those that did not. Comparison of in-hospital care quality, procedure use, and mortality between expansion and nonexpansion states for the years prior to and after Medicaid expansion. Hierarchical logistic regressions models were used to assess the association between Medicaid expansion and outcomes.
Results
The initial cohort included 325 343 patients. Uninsured AMI hospitalizations declined in expansion states (18.0% [4395 of 24 358 hospitalizations] to 8.4% [2638 of 31 382 hospitalizations]) and more modestly in nonexpansion states (25.6% [7963 of 31 137 hospitalizations] to 21.1% [8668 of 41 120 hospitalizations]) from 2012 to 2016 (P < .001 difference in trend expansion vs nonexpansion). Medicaid coverage increased from 7.5% (1818 of 24 358 hospitalizations) to 14.4% (4502 of 31 382 hospitalizations) in expansion states and 6.2% (1924 of 31 137 hospitalizations) to 6.6% (2717 of 41 120 hospitalizations) in nonexpansion states (P < .001). The low-income cohort included 55 737 patients across 765 sites. In expansion states, low-income adults’ odds of receipt of defect-free care increased (76.3% to 75.9%, adjusted odds ratio 1.11; 95% CI, 1.02-1.21) but to a lesser degree than in nonexpansion states (72.8% to 74.5%, adjusted odds ratio, 1.38; 95% CI, 1.30-1.47; P for interaction < .001). There was no change in use of most procedures (ie, percutaneous coronary intervention for non–ST-segment elevation myocardial infarction) in expansion compared with nonexpansion states. Improvement in in-hospital mortality was similar between expansion and nonexpansion states (3.2% to 2.8%, adjusted odds ratio, 0.93; 95% CI, 0.77-1.12 vs 3.3% to 3.0%, adjusted odds ratio, 0.85; 95% CI, 0.73-0.99; P for interaction = .48).
Conclusions and Relevance
Medicaid expansion was associated with a significant reduction in rates of uninsurance among patients hospitalized with AMI. Quality of care and outcomes did not improve among low-income adults in expansion compared with nonexpansion states. Hospital care for AMI may be less sensitive to insurance than has been recognized in the past.
Introduction
Despite considerable progress in the treatment of acute myocardial infarction (AMI), major disparities in care remain for uninsured individuals. Although rates of AMI among the general population have declined in recent years,1 the proportion of patients hospitalized for AMI who are uninsured has been rising.2 Lack of insurance is associated with delays in seeking emergency care for patients with AMI,3 and uninsured patients with AMI are less likely to receive guideline-directed medical therapy, aggressive care, and invasive cardiac procedures than their insured counterparts.4,5 These factors, at least in part, may explain why patients without insurance have higher mortality rates after an AMI compared with insured individuals.5,6
In 2014, Medicaid eligibility was expanded under the Patient Protection and Affordable Care Act (ACA), and millions of low-income adults gained insurance coverage in more than 30 states.7 While prior studies have demonstrated that Medicaid expansion is associated with better access to outpatient care for low-income patients,8,9,10,11 little is known about its impact on inpatient care quality and outcomes for acute, life-threatening conditions such as AMI. There are a few mechanisms by which insurance might be associated with better care for AMI. First, individuals with insurance may receive better longitudinal outpatient care and as a result, have fewer or better treated clinical comorbidities at time of AMI presentation. Second, individuals having symptoms of an AMI who are insured might be more proactive in seeking medical care in a timely fashion if they are not worried about the potential financial implications. Third, insurance could influence care delivered during hospitalization, such as expensive procedures, by removing any financial barriers to optimal care delivery.
Given evidence of substantial disparities in AMI care for uninsured individuals, and ongoing debate in nonexpansion states regarding whether to expand Medicaid, understanding the association of Medicaid expansion with uninsured rates, quality of care, and outcomes among patients hospitalized for AMI is particularly important. Therefore, in this study, we aimed to answer 3 questions. First, did rates of uninsurance and Medicaid insurance change among adults hospitalized for AMI after the ACA’s Medicaid expansion? Second, did inpatient care quality and procedure use change for low-income patients in states that elected to expand Medicaid compared with states that did not expand? And finally, did in-hospital outcomes improve in states that expanded Medicaid compared with nonexpansion states?
Methods
This registry was either approved by institutional review board or considered quality improvement data and not subject to institutional review board approval based on determinations from the individual sites, of which there were more than 800. The need for informed consent was also waived because all data were collected retrospectively and anonymously without unique patient identifiers.
Data Source
We used the National Cardiovascular Data Registry (NCDR) Acute Coronary Treatment and Intervention Outcomes Network (ACTION), the largest ongoing quality improvement registry of AMI in the United States, to examine the association between state Medicaid expansions and care quality and outcomes among low-income patients younger than 65 years hospitalized with AMI. The National Cardiovascular Data Registry ACTION care process and outcomes metrics are based on the recommendations of the National Quality Foundation, are endorsed by the American College of Cardiology/American Heart Association Task Force on Performance Measures, and are aligned with measures used by Centers for Medicare and Medicaid Services to assess quality of care.12 Institutions participating in the ACTION Registry report detailed information on baseline patient demographics, clinical characteristics, care processes, and in-hospital outcomes for all patients initially presenting with AMI. The NCDR data are screened for completeness and accuracy during web-based entry, and quality assurance is maintained through the use of standardized data definitions, uniform data transmission protocols, and routine data quality checks and audits.13,14
Medicaid Expansion Status
We considered expansion states to be those that expanded Medicaid during 2014 (eTable 1 in the Supplement). We excluded Washington, DC, and 4 states (Delaware, Massachusetts, New York, and Vermont) from the low-income analysis because they already provided Medicaid coverage to low-income adults from 2010 through 2013 that was comparable with the ACA’s Medicaid expansion. We also excluded 2 states that expanded in mid-2015 (Indiana and Alaska). The remaining states were considered nonexpansion states and served as a control group for comparison.
Our preintervention period included the 2 years prior to expansion (January 1, 2012, to December 31, 2013), and our intervention period included the 2 years after expansion (January 1, 2015, to December 31, 2016). We excluded the year immediately after the start of Medicaid expansion (January 1, 2014, to December 31, 2014) from our analysis of low-income adults to account for potential lag effect and because some states expanded midway through 2014. Analysis was conducted from December 2017 to March 2018.
Patient Cohort
We identified 675 966 patients hospitalized for AMI between January 1, 2012, and December 31, 2016. We first excluded patients 26 years or younger because they are eligible for insurance through their parents’ insurance plan under the ACA in all states as well as patients 65 years or older who would be eligible for Medicare insurance. We then used this cohort (n = 325 343) to characterize trends in AMI hospitalizations by insurance status (Medicaid or uninsured) before and after Medicaid expansion.
For the analysis comparing quality of care, procedure use, and outcomes, we identified a low-income cohort by only including patients who were covered by Medicaid or uninsured at the time of hospitalization. We chose to exclude patients younger than 65 years who were insured by other (non-Medicaid) payors, as Medicaid expansion would be expected to have little effect on this already insured population. Our analytic cohort included 55 737 low-income patients younger than 65 years hospitalized for AMI from January 1, 2012, to December 31, 2013 (preexpansion period), and January 1, 2015, to December 31, 2016 (postexpansion period).
The race/ethnicity of all patients was identified based on registry data and was designated into fixed categories: white, black, Asian, Hispanic, or other. Race/ethnicity was included as a covariate in the analysis because it is associated with quality of care and mortality for AMI.15
Performance, Quality, and Outcome Measures
In the low-income cohort, we assessed all performance and quality measures before and after Medicaid expansion in expansion and nonexpansion states. We first characterized rates of defect-free AMI care for eligible patients, defined as 100% compliance with all required performance and/or quality measures for which each patient was eligible. The major measures evaluated in the study that comprised the defect-free AMI care measure were (1) aspirin at arrival, (2) aspirin prescribed at discharge, (3) β-blocker prescribed at discharge, (4) statin prescribed at discharge, (5) angiotensin-converting enzyme inhibitor or angiotensin receptor blocker for left ventricular systolic dysfunction, (6) reperfusion therapy (ST-segment elevation myocardial infarction [STEMI]), (7) time to primary percutaneous coronary intervention (PCI) 90 minutes or less (STEMI), (8) time to fibrinolytic therapy administration 30 minutes or less (STEMI), (9) evaluation of left ventricular systolic function, (10) adult smoking cessation advice/counseling, and (11) cardiac rehabilitation patient referral. Our main outcomes of interest were in-hospital death, major bleeding, and prolonged length of stay (>3 days vs ≤3 days).
Statistical Analysis
In the overall cohort, trends in counts and the proportion of AMI hospitalizations were described by insurance status (Medicaid or uninsured) from 2012 to 2016 and stratified by expansion vs nonexpansion status. Cochran-Armitage test was used to evaluate trends. To determine whether temporal trends in AMI hospitalizations for each insurance type differed between expansion and nonexpansion states, we used an unadjusted random-effect model with random hospital intercepts and added a categorical time and expansion status interaction.
Next, for the low-income cohort, baseline patient characteristics including demographic information and medical history were summarized for periods before and after Medicaid expansion by state expansion status. Other clinical data, including vital signs at admission, laboratory values during hospitalization (ie, troponin, creatinine), type of AMI (non–ST-segment elevation myocardial infarction [NSTEMI], STEMI), diagnostic and therapeutic interventions (ie, PCI, coronary artery bypass grafting, thrombolytic therapy), and outcomes and complications were similarly described. Categorical variables were compared using Pearson χ2 tests and continuous variables using the Wilcoxon test.
Hierarchical logistic regression models with a random intercept for hospitals were then used to assess the association between expansion and our outcomes of interest. The model included an indicator for pre- vs postexpansion, an indicator for state expansion status, and the interaction between the 2. Models for care quality and diagnostic/therapeutic interventions were adjusted to account for hospital clustering effect. Models for clinical outcomes (bleeding, mortality, and length of stay) were additionally adjusted to account for differing patient and clinical characteristics including (1) patient demographics (age, sex, race, weight), (2) medical history (peripheral artery disease, hypertension, diabetes mellitus, current/recent smoker, dyslipidemia, prior myocardial infarction, prior PCI, prior coronary artery bypass graft, prior congestive heart failure, prior stroke, prior atrial fibrillation or flutter), (3) home medications (aspirin, clopidogrel, warfarin, β-blocker, angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, aldosterone antagonist, statin, and nonstatin lipid-lowering agent), (4) signs and symptoms (systolic blood pressure, heart rate, STEMI, heart failure, cardiogenic shock, cardiac arrest), and (5) laboratory results (initial troponin ratio, initial hemoglobin [grams per deciliter], creatinine clearance). For each outcome, we calculated an odds ratio (OR) (with 95% CI and P values) for the preexpansion and postexpansion periods, by state expansion status, and then tested for interaction.
Missing continuous variables were imputed to relevant medians among nonmissing values and missing categorical variables were imputed to mode. Flexible splines of continuous variables for adjustment were used to fit the models.
Additional Analysis
As a supplementary analysis, we identified patients with home zip codes in the lowest quintile of median household income (≤$37 060), based on American Community Survey 2011-2015 data.16 We repeated all analyses described above for this cohort to determine if using an alternate method to identify low-income patients resulted in findings similar to our main analysis. All statistical tests were 2 sided at a significance level of .05. Analyses were performed using SAS software (version 9.4; SAS Institute).
Results
Hospitalization Trends by Insurance
Of all AMI hospitalizations among adults younger than 65 years, the annual proportion of patients insured by Medicaid increased from 7.5% (1818 of 24 358 hospitalizations) to 14.4% (4502 of 31 382 hospitalizations) in expansion states and 6.2% (1924 of 31 137 hospitalizations) to 6.6% (2717 of 41 120 hospitalizations) in nonexpansion states from 2012 to 2016 (P < .001 for difference in trend between expansion vs nonexpansion states; Figure, A). During the same time, the annual proportion of uninsured AMI hospitalizations declined significantly in expansion states (18.0% [4395 of 24 358 hospitalizations] to 8.4% [2638 of 31 382 hospitalizations]) and more modestly in nonexpansion states (25.6% [7963 of 31 137 hospitalizations] to 21.1% [8668 of 41 120 hospitalizations], P < .001 for difference in trend; Figure, B). The number of Medicaid and uninsured hospitalizations in expansion and nonexpansion states per year are shown in the eFigure in the Supplement.
Figure. Medicaid and Uninsured Acute Myocardial Infarction Hospitalization Rates in Expansion vs Nonexpansion States.
Proportion of all patients younger than 65 years who were insured by Medicaid (A) or uninsured (B) at time of hospitalization for AMI in expansion (blue) and nonexpansion (orange) states. Both P < .001 for the difference in temporal trend of Medicaid/uninsured patients in expansion vs nonexpansion states.
Study Population
The low-income cohort included 55 737 patients, of whom 38 786 (69.6%) were uninsured and 16 951 (30.4%) were insured with Medicaid. Of these patients, 21 378 (38.4%) were hospitalized at 550 sites in expansion states, and 34 359 (61.6%) were hospitalized at 566 sites in nonexpansion states during the study period.
In both expansion and nonexpansion states, baseline demographics and clinical characteristics among low-income patients were fairly well matched during the pre- and postexpansion periods (Table 1). Low-income patients in expansion states were significantly more likely to be covered by Medicaid after expansion (30.3% [3172 of 10 475 hospitalizations] vs 61.4% [6694 of 10 903 hospitalizations], P < .001) and less likely to be uninsured (69.7% [7303 of 10 475 hospitalizations] vs 38.6% [4209 of 10 903 hospitalizations], P < .001). These differences were much more modest among nonexpansion states.
Table 1. Baseline Low-Income Patient Characteristics in the Preexpansion and Postexpansion Periods by State Medicaid Expansion Status.
| Variable | Expansion States, No. (%) | P Value | Nonexpansion States, No. (%) | P Value | ||
|---|---|---|---|---|---|---|
| Preexpansion Period (n = 10 475) | Postexpansion Period (n = 10 903) | Preexpansion Period (n = 16 470) | Postexpansion Period (n = 17 889) | |||
| Age, median (IQR), y | 53.0 (47.0-58.0) | 53.0 (47.0-59.0) | .06 | 53.0 (47.0-58.0) | 53.0 (47.0-58.0) | .20 |
| Sex | ||||||
| Male | 7457 (71.2) | 7735 (70.9) | .69 | 11668 (70.8) | 12483 (69.8) | .03 |
| Female | 3018 (28.8) | 3168 (29.1) | 4802 (29.2) | 5406 (30.2) | ||
| Race/ethnicity | ||||||
| White | 7699 (73.9) | 7598 (70.5) | <.001 | 10 582 (64.5) | 11 463 (64.4) | .003 |
| Black | 1362 (13.1) | 1481 (13.7) | 3419 (20.8) | 3701 (20.8) | ||
| Asian | 303 (2.9) | 365 (3.4) | 318 (1.9) | 292 (1.6) | ||
| Hispanic | 951 (9.1) | 1199 (11.1) | 2003 (12.2) | 2187 (12.3) | ||
| Other | 101 (1.0) | 138 (1.3) | 84 (0.5) | 146 (0.8) | ||
| Insurance status | ||||||
| Medicaid | 3172 (30.3) | 6694 (61.4) | <.001 | 3052 (18.5) | 4033 (22.5) | <.001 |
| Uninsured | 7303 (69.7) | 4209 (38.6) | 13418 (81.5) | 13856 (77.5) | ||
| Clinical comorbidities | ||||||
| Diabetes mellitus | 2895 (27.6) | 3036 (27.9) | .73 | 4608 (28.0) | 5228 (29.2) | .01 |
| Dyslipidemia | 4845 (46.3) | 4884 (44.8) | .03 | 7419 (45.1) | 7559 (42.3) | <.001 |
| Hypertension | 6503 (62.1) | 6666 (61.2) | .16 | 10 507 (63.8) | 11 668 (65.2) | .006 |
| Current/recent smoker (<1 y) | 6709 (64.1) | 6647 (61.0) | <.001 | 10 499 (63.8) | 11 364 (63.5) | .66 |
| Prior | ||||||
| MI | 2047 (19.6) | 1968 (18.1) | .01 | 3246 (19.7) | 3331 (18.6) | .01 |
| PCI | 1981 (18.9) | 1929 (17.7) | .02 | 3180 (19.3) | 3362 (18.8) | .22 |
| CABG | 582 (5.6) | 470 (4.3) | <.001 | 849 (5.2) | 918 (5.1) | .92 |
| HF | 663 (6.3) | 645 (5.9) | .20 | 1042 (6.3) | 1270 (7.1) | .004 |
| Stroke (overall) | 424 (4.1) | 441 (4.0) | .99 | 772 (4.7) | 887 (5.0) | .24 |
| Peripheral arterial disease | 457 (4.4) | 408 (3.7) | .02 | 698 (4.2) | 671 (3.8) | .02 |
| Atrial fibrillation or flutter (past 2 wk) | 278 (2.7) | 322 (3.0) | .19 | 445 (2.7) | 528 (3.0) | .16 |
| Clinical characteristics (hospitalization), median (IQR) | ||||||
| Systolic BP on admission, mm Hg | 146.0 (125.0-167.0) | 147.0 (126.0-169.0) | .01 | 147.0 (126.0-170.0) | 149.0 (128.0-172.0) | <.001 |
| Heart rate on admission, bpm | 83.0 (70.0-98.0) | 83.0 (70.0-98.0) | .50 | 83.0 (70.0-98.0) | 84.0 (70.0-98.0) | .04 |
| MI type | ||||||
| NSTEMI | 5237 (50.0) | 5444 (49.9) | .93 | 8309 (50.4) | 9350 (52.3) | <.001 |
| STEMI | 5238 (50.0) | 5459 (50.1) | 8161 (49.6) | 8539 (47.7) | ||
| Cardiac arrest | 605 (5.8) | 588 (5.4) | .21 | 839 (5.1) | 876 (4.9) | .41 |
| Cardiogenic shock | 482 (4.6) | 455 (4.2) | .13 | 728 (4.4) | 712 (4.0) | .04 |
| Signs of HF | 841 (8.0) | 771 (7.1) | .01 | 1498 (9.1) | 1626 (9.1) | .99 |
Abbreviations: BP, blood pressure; bpm, beats per minute; CABG, coronary artery bypass graft; HF, heart failure; IQR, interquartile range; MI, myocardial infarction; NSTEMI, non–ST-segment elevation myocardial infarction; PCI, percutaneous coronary intervention; STEMI, ST-segment elevation myocardial infarction.
The proportion of patients hospitalized for NSTEMI and STEMI were similar during the pre- and postexpansion periods in both expansion and nonexpansion states. Patients in expansion states were less likely to have signs of heart failure in the post- compared with preexpansion periods (8.0% vs 7.1%, P = .008) but had similar rates of cardiac arrest (5.8% vs 5.4%, P = .21) and cardiogenic shock (4.6% vs 4.2%, P = .13). Among nonexpansion states, rates of cardiac arrest and heart failure were similar in both periods, although cardiogenic shock was less common in the postexpansion period (4.4% vs 4.0% P = .04; Table 1). Data on home medications and admission laboratory values are shown in eTable 2 in the Supplement.
Association of Expansion With Care Quality
Patients in expansion states had higher odds of receiving defect-free AMI care in the postexpansion period than the preexpansion period (observed rate: preexpansion 76.3% vs postexpansion 75.9%, adjusted OR of post- vs preexpansion: 1.11; 95% CI, 1.02-1.21; P = .01, Table 2). However, the increase in defect-free care during the postexpansion period among nonexpansion states was even greater (72.8% vs 74.5%, adjusted OR, 1.38; 95% CI, 1.30-1.47; P < .001; P for interaction < .001).
Table 2. Association of Medicaid Expansion With Quality of Care and Diagnostic/Therapeutic Interventions by State Expansion Status.
| Variable | Patients in Expansion States, No. (%) | P Value | Patients in Nonexpansion States, No. (%) | P Value | P Value for Interactionc | ||||
|---|---|---|---|---|---|---|---|---|---|
| Preexpansion (n = 10 070)a | Postexpansion (n = 10 427)a | Post- vs Preexpansion, Adjusted OR (95% CI)b | Preexpansion (n = 15 961)a | Postexpansion (n = 17 285)a | Post- vs Preexpansion, Adjusted OR (95% CI)b | ||||
| Quality of care | |||||||||
| Defect-free AMI care | 7448 (76.3) | 7555 (75.9) | 1.11 (1.02-1.21) | .01 | 11 276 (72.8) | 12 276 (74.5) | 1.38 (1.30-1.47) | <.001 | <.001 |
| Diagnostic and therapeutic interventions | |||||||||
| Diagnostic catheterization | 9655 (95.9) | 10 003 (95.9) | 1.02 (0.88-1.20) | .76 | 15 199 (95.2) | 16 425 (95.0) | 1.05 (0.94-1.17) | .41 | .82 |
| Thrombolytic therapy for patients with STEMI | 315 (6.2) | 335 (6.4) | 0.83 (0.68-1.01) | .06 | 460 (5.8) | 484 (5.8) | 0.97 (0.82-1.13) | .66 | .23 |
| Primary PCI only for STEMI | 4343 (97.4) | 4575 (95.7) | 0.66 (0.50-0.87) | .003 | 6718 (97.6) | 7161 (94.8) | 0.45 (0.36-0.55) | <.001 | .03 |
| PCI for NSTEMI | 2937 (58.9) | 3149 (61.0) | 1.08 (0.99-1.18) | .10 | 4522 (56.3) | 5107 (57.0) | 1.04 (0.97-1.11) | .24 | .52 |
| CABG | 834 (8.3) | 749 (7.2) | 0.94 (0.84-1.05) | .26 | 1439 (9.0) | 1520 (8.8) | 0.97 (0.90-1.06) | .50 | .60 |
Abbreviations: AMI, acute myocardial infarction; CABG, coronary artery bypass graft; NSTEMI, non–ST-segment elevation myocardial infarction; OR, odds ratio; PCI, percutaneous coronary intervention; STEMI, ST-segment elevation myocardial infarction.
Observed rates among eligible patients. A total of 1994 transfer-out patients were excluded.
Odds ratios are adjusted to account for hospital clustering.
P value for interaction in this case tests the interaction between pre-post and expansion status, to determine whether the difference between pre- and postperiods differs by expansion and nonexpansion states.
There was no change from the pre- to postexpansion period in either expansion or nonexpansion states in the use of diagnostic cardiac catheterization, PCI for NSTEMI, or coronary artery bypass graft. However, in expansion and nonexpansion states, the adjusted odds of use of primary PCI for STEMI were lower in the postexpansion period, relative to preexpansion, although this decline was more pronounced in nonexpansion states (Table 2).
Association of Expansion With In-Hospital Outcomes
Among expansion states, patients hospitalized for AMI had similar rates of in-hospital death during the pre- and postexpansion periods (3.2% vs 2.8%, adjusted OR of post- vs preexpansion: 0.93; 95% CI, 0.77-1.12; P = .44; Table 3). In-hospital death declined slightly from pre- to postexpansion periods among nonexpansion states (3.3% vs 3.0%, adjusted OR, 0.85; 95% CI, 0.73-0.99; P = .03). There was no differential change in death between expansion and nonexpansion states associated with expansion (P for interaction = .48). Similarly, there were no differential changes in major bleeding or length of stay between expansion and nonexpansion states.
Table 3. Association of Medicaid Expansion With In-Hospital Outcomes by State Expansion Status.
| Outcomes | Patients in Expansion States, No. (%) | P Value | Patients in Nonexpansion States, No. (%) | P Value | P Value for Interactionc | ||||
|---|---|---|---|---|---|---|---|---|---|
| Preexpansiona | Postexpansiona | Post- vs Preexpansion, Adjusted OR (95% CI)b | Preexpansiona | Postexpansiona | Post- vs Preexpansion, Adjusted OR (95% CI)b | ||||
| Death | 324 (3.2) | 296 (2.8) | 0.93 (0.77-1.12) | .44 | 523 (3.3) | 514 (3.0) | 0.85 (0.73-0.99) | .03 | .48 |
| Major bleeding | 728 (7.3) | 625 (6.1) | 0.79 (0.70-0.90) | <.001 | 1127 (7.1) | 1038 (6.0) | 0.77 (0.70-0.85) | <.001 | .69 |
| Length of stay >3 dd | 2176 (32.6) | 2041 (29.2) | 0.80 (0.74-0.88) | <.001 | 3727 (34.5) | 3651 (31.4) | 0.82 (0.76-0.87) | <.001 | .81 |
Abbreviation: OR, odds ratio.
Observed rates among eligible patients. A total of 1994 transfer-out patients were excluded.
Odds ratios are adjusted for patient demographics, medical history, home medications, signs and symptoms, laboratory results, and hospital clustering (see the Methods section).
P for interaction in this case tests the interaction between pre-post and expansion status, to determine whether the difference between pre- and postperiods differs by expansion and nonexpansion states.
For length of stay, transfer-in patients (n = 16 286), patients who died in hospital (n = 1229), and patients with missing length of stay (n = 155) were excluded.
Additional Analysis
As a supplementary analysis, we examined an alternative definition of low-income, namely patients in the lowest quintile of median household income (≤$37 060). This low-income cohort included 40 359 patients (eTables 3 and 4 in the Supplement), of whom 12 403 (30.7%) were hospitalized at 454 sites in expansion states and 27 956 (69.3%) at 506 sites in nonexpansion states. Changes in care quality and outcomes after Medicaid expansion paralleled our main analysis (eTables 5 and 6 in the Supplement).
Discussion
In this study, we explored the association of the ACA’s Medicaid expansion with rates of uninsurance, quality of care, diagnostic and therapeutic procedure use, and outcomes among adults hospitalized with AMI. We found that patients hospitalized for AMI were significantly less likely to be uninsured and more likely to be insured by Medicaid in states that adopted expansion compared with nonexpansion states. Among low-income patients, we did not observe improvements in AMI care quality associated with expansion. In addition, the use of diagnostic and therapeutic interventions, such as cardiac catheterization or PCI, did not increase significantly after expansion. These patterns may, at least in part, explain why expansion was also not associated with improvements in in-hospital mortality.
Contrary to prior work showing improvements in outpatient care and perhaps in population-level mortality,8,17,18,19,20,21,22 we found that in-hospital quality of care and mortality for AMI did not significantly improve after expansion. This may, in part, be because expansion was not associated with a decline in hospitalizations for cardiogenic shock (or cardiac arrest), conditions that might potentially reflect delays in seeking care. In addition, expansion did not result in better inpatient care quality, such as defect-free AMI care, and the use of potentially life-saving interventions, such as PCI for NSTEMI, did not change significantly after implementation of expansion. Health insurance plays an important role mediating access to health care services, but these data indicate that lack of insurance may not necessarily influence care quality and clinician decision making once a patient is hospitalized for an acute condition.11 A 2018 study similarly demonstrated no association between Medicaid expansion and in-hospital mortality for major cardiovascular events but was limited to fewer states, did not examine changes in care quality and procedure use for AMI, and assessed a single postexpansion year, which may have been too short to appreciate the incremental, cumulative health benefits of reliable access to outpatient care.23,24 Our study builds on this evidence by providing a comprehensive picture of in-hospital care and outcomes 3 years after the implementation of Medicaid expansion.
Prior studies have shown that expansion has been associated with a number of benefits in the outpatient setting, such as greater access to primary, preventive, and specialist care.8,20 Identification and treatment of cardiovascular risk factors, such as diabetes and hypertension, have improved since Medicaid expansion.25,26,27 Furthermore, use of prescription cardiovascular drugs, which play an important role in primary and secondary prevention of AMI, and adherence to medications has increased.8,28 Our findings suggest that these improvements have not translated into differences in acuity of presentation nor in clinical outcomes. Another potential explanation is that targeted hospital quality improvement initiatives have narrowed previously observed in-hospital disparities in AMI care over time,29 leaving little room for further improvement, given that we generally observed high-quality AMI care regardless of insurance status in our study.4,5,6
Notably, by the end of the study, the rate of uninsured AMI hospitalizations in expansion states had declined to less than half that of nonexpansion states. Although we did not find differences in clinical outcomes, this shift in coverage has important financial ramifications. Prior to the ACA, an estimated 85% of uninsured individuals hospitalized for AMI experienced catastrophic health care expenditures.30 Health insurance mitigates patients’ financial risk, particularly for emergent, high-cost conditions such as AMI, and prior analyses have shown that Medicaid expansion is associated with reductions in financial strain and bankruptcies.19,31 Thus, the significant decline we observed in uninsured hospitalizations after implementation of Medicaid expansions suggests that fewer low-income patients may have experienced financial hardship in these states.
Limitations
Our study has limitations. First, the NCDR ACTION registry enrolls patients who may not necessarily be representative of all hospitals across the United States and reflect sites that have an interest in quality improvement. However, our analysis did include more than 700 acute care hospitals in the United States. Second, our data only include patients with AMI admitted to a hospital; patients who died prior to reaching the hospital or discharged from the emergency department were not included. Third, our analysis was observational in nature, and it is possible that external factors changed over time and confounded our temporal comparison of expansion and nonexpansion states. Fourth, we were unable to evaluate care in the postdischarge period. Insurance facilitates access to outpatient and specialist (cardiology) care, which is associated with greater cardiac medication adherence and lower mortality during the vulnerable period after discharge.32,33 It is possible that being insured after an AMI hospitalization provides greater benefit in the long term, and this represents an important area for future research.
Conclusions
In summary, we found that adults younger than 65 years hospitalized for AMI were significantly less likely to be uninsured after the implementation of Medicaid expansion compared with nonexpansion states. This has important implications regarding the financial protection and security, through insurance, of vulnerable patients. Among low-income adults hospitalized for AMI, Medicaid expansion was not associated with improved quality of care or better outcomes. These findings suggest that current care systems for urgent, time-sensitive conditions may be less sensitive to insurance than has been recognized in the past.
eFigure. Trends in Number of Uninsured and Medicaid-Insured Patients Hospitalized for Acute Myocardial Infarction in Expansion States (Panel A) and Non-Expansion States (Panel B)
eTable 1. Categorization of Medicaid Expansion vs. Non-Expansion States
eTable 2. Home Medications and Laboratory Values during Hospitalization in the Pre- and Post-Expansion Periods by State Expansion Status
eTable 3. Baseline Patient Characteristics in the Pre- and Post-Expansion Periods by State Expansion Status (Lowest Income Quintile Cohort)
eTable 4. Home Medications and Laboratory Values during Hospitalization in the Pre- and Post-Expansion Periods by State Expansion Status (Lowest Income Quintile Cohort)
eTable 5. Association of Medicaid Expansion with Quality of Care and Diagnostic/Therapeutic Interventions by State Expansion Status (Lowest Income Quintile Cohort)
eTable 6. Association of Medicaid Expansion with In-Hospital Outcomes by State Expansion Status (Lowest Income Quintile Cohort)
References
- 1.Yeh RW, Sidney S, Chandra M, Sorel M, Selby JV, Go AS. Population trends in the incidence and outcomes of acute myocardial infarction. N Engl J Med. 2010;362(23):2155-2165. doi: 10.1056/NEJMoa0908610 [DOI] [PubMed] [Google Scholar]
- 2.Doran B, Guo Y, Xu J, Bangalore S. Abstract 18272: the increasing proportion of acute myocardial infarction represented by the uninsured: a growing financial burden in the United States. Circulation. 2018;130:A18272. [Google Scholar]
- 3.Smolderen KG, Spertus JA, Nallamothu BK, et al. Health care insurance, financial concerns in accessing care, and delays to hospital presentation in acute myocardial infarction. JAMA. 2010;303(14):1392-1400. doi: 10.1001/jama.2010.409 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Cho L, Bhatt DL, Brennan D, Wilcox RG, Topol EJ. Relation of insurance status to performance of coronary angiography in patients with unstable angina pectoris or acute myocardial infarction. Am J Cardiol. 2003;91(6):721-723. doi: 10.1016/S0002-9149(02)03413-6 [DOI] [PubMed] [Google Scholar]
- 5.Canto JG, Rogers WJ, French WJ, Gore JM, Chandra NC, Barron HV. Payer status and the utilization of hospital resources in acute myocardial infarction: a report from the National Registry of Myocardial Infarction 2. Arch Intern Med. 2000;160(6):817-823. doi: 10.1001/archinte.160.6.817 [DOI] [PubMed] [Google Scholar]
- 6.Vidovich MI, Vasaiwala S, Cannon CP, et al. ; Get With Guidelines Steering Committee and Investigators . Association of insurance status with inpatient treatment for coronary artery disease: findings from the Get With the Guidelines program. Am Heart J. 2010;159(6):1026-1036. doi: 10.1016/j.ahj.2010.03.013 [DOI] [PubMed] [Google Scholar]
- 7.Kaiser Family Foundation Status of state Medicaid expansion decisions: interactive map. https://www.kff.org/medicaid/issue-brief/status-of-state-medicaid-expansion-decisions-interactive-map/. Accessed December 3, 2018.
- 8.Sommers BD, Blendon RJ, Orav EJ, Epstein AM. Changes in utilization and health among low-income adults after Medicaid expansion or expanded private insurance. JAMA Intern Med. 2016;176(10):1501-1509. doi: 10.1001/jamainternmed.2016.4419 [DOI] [PubMed] [Google Scholar]
- 9.Sommers BD, Maylone B, Blendon RJ, Orav EJ, Epstein AM. Three-year impacts of the Affordable Care Act: improved medical care and health among low-income adults. Health Aff (Millwood). 2017;36(6):1119-1128. doi: 10.1377/hlthaff.2017.0293 [DOI] [PubMed] [Google Scholar]
- 10.Simon K, Soni A, Cawley J. The impact of health insurance on preventive care and health behaviors: evidence from the first two years of the ACA Medicaid expansions. J Policy Anal Manage. 2017;36(2):390-417. doi: 10.1002/pam.21972 [DOI] [PubMed] [Google Scholar]
- 11.Sommers BD, Gawande AA, Baicker K. Health insurance coverage and health: what the recent evidence tells us. N Engl J Med. 2017;377(6):586-593. doi: 10.1056/NEJMsb1706645 [DOI] [PubMed] [Google Scholar]
- 12.Metrics and Measures. Quality Improvement for Institutions https://cvquality.acc.org/NCDR-Home/reports/metrics-and-measures. Accessed December 3, 2018.
- 13.Messenger JC, Ho KK, Young CH, et al. ; NCDR Science and Quality Oversight Committee Data Quality Workgroup . The National Cardiovascular Data Registry (NCDR) data quality brief: the NCDR data quality program in 2012. J Am Coll Cardiol. 2012;60(16):1484-1488. doi: 10.1016/j.jacc.2012.07.020 [DOI] [PubMed] [Google Scholar]
- 14.Masoudi FA, Ponirakis A, Yeh RW, et al. Cardiovascular care facts: a report from the national cardiovascular data registry: 2011. J Am Coll Cardiol. 2013;62(21):1931-1947. doi: 10.1016/j.jacc.2013.05.099 [DOI] [PubMed] [Google Scholar]
- 15.Downing NS, Wang C, Gupta A, et al. Association of racial and socioeconomic disparities with outcomes among patients hospitalized with acute myocardial infarction, heart failure, and pneumonia an analysis of within- and between-hospital variation. JAMA Netw Open. 2018;1(5):e182044. doi: 10.1001/jamanetworkopen.2018.2044 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.American Community Survey. United States Census Bureau. https://www.census.gov/programs-surveys/acs/data.html. Accessed December 7, 2018.
- 17.Sommers BD, Baicker K, Epstein AM. Mortality and access to care among adults after state Medicaid expansions. N Engl J Med. 2012;367(11):1025-1034. doi: 10.1056/NEJMsa1202099 [DOI] [PubMed] [Google Scholar]
- 18.Sommers BD, Long SK, Baicker K. Changes in mortality after Massachusetts health care reform. Ann Intern Med. 2015;162(9):668-669. doi: 10.7326/L15-5085-2 [DOI] [PubMed] [Google Scholar]
- 19.Baicker K, Taubman SL, Allen HL, et al. ; Oregon Health Study Group . The Oregon experiment: effects of Medicaid on clinical outcomes. N Engl J Med. 2013;368(18):1713-1722. doi: 10.1056/NEJMsa1212321 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Sommers BD, Gunja MZ, Finegold K, Musco T. Changes in self-reported insurance coverage, access to care, and health under the Affordable Care Act. JAMA. 2015;314(4):366-374. doi: 10.1001/jama.2015.8421 [DOI] [PubMed] [Google Scholar]
- 21.Miller S, Wherry LR. Health and access to care during the first 2 years of the ACA Medicaid expansions. N Engl J Med. 2017;376(10):947-956. doi: 10.1056/NEJMsa1612890 [DOI] [PubMed] [Google Scholar]
- 22.Health Insurance Coverage of Adults 19-64. The Kaiser Family Foundation. https://www.kff.org/other/state-indicator/adults-19-64/?currentTimeframe=0&sortModel=%7B%22colId%22:%22Location%22,%22sort%22:%22asc%22%7D. Accessed December 3, 2018.
- 23.Akhabue E, Pool LR, Yancy CW, Greenland P, Lloyd-Jones D. Association of state Medicaid expansion with rate of uninsured hospitalizations for major cardiovascular events, 2009-2014. JAMA Netw Open. 2018;1(4):e181296. doi: 10.1001/jamanetworkopen.2018.1296 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Wadhera RK, Joynt Maddox KE. Medicaid expansion and in-hospital cardiovascular mortality: failure or unrealistic expectations? JAMA Netw Open. 2018;1(4):e181303. doi: 10.1001/jamanetworkopen.2018.1303 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Wherry LR, Miller S. Early coverage, access, utilization, and health effects associated with the Affordable Care Act Medicaid expansions: a quasi-experimental study. Ann Intern Med. 2016;164(12):795-803. doi: 10.7326/M15-2234 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Kaufman HW, Chen Z, Fonseca VA, McPhaul MJ. Surge in newly identified diabetes among medicaid patients in 2014 within Medicaid expansion states under the affordable care act. Diabetes Care. 2015;38(5):833-837. doi: 10.2337/dc14-2334 [DOI] [PubMed] [Google Scholar]
- 27.Cole MB, Galárraga O, Wilson IB, Wright B, Trivedi AN. At federally funded health centers, Medicaid expansion was associated with improved quality of care. Health Aff (Millwood). 2017;36(1):40-48. doi: 10.1377/hlthaff.2016.0804 [DOI] [PubMed] [Google Scholar]
- 28.Ghosh A, Simon K, Sommers BD. The effect of state Medicaid expansions on prescription drug use: evidence from the Affordable Care Act. Cambridge, MA: National Bureau of Economic Research; 2017. doi: 10.3386/w23044 [DOI] [Google Scholar]
- 29.Masoudi FA, Ponirakis A, de Lemos JA, et al. Trends in US Cardiovascular Care: 2016 Report From 4 ACC national cardiovascular data registries. J Am Coll Cardiol. 2017;69(11):1427-1450. doi: 10.1016/j.jacc.2016.12.005 [DOI] [PubMed] [Google Scholar]
- 30.Khera R, Hong JC, Saxena A, et al. Burden of Catastrophic Health Expenditures for Acute Myocardial Infarction and Stroke Among Uninsured in the United States. Circulation. 2018;137(4):408-410. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Hu L, Kaestner R, Mazumder B, Miller S, Wong A. The effect of the Patient Protection and Affordable Care Act Medicaid expansions on financial well-being. Cambridge, MA: National Bureau of Economic Research; 2016. doi: 10.3386/w22170 [DOI] [Google Scholar]
- 32.Ayanian JZ, Landrum MB, Guadagnoli E, Gaccione P. Specialty of ambulatory care physicians and mortality among elderly patients after myocardial infarction. N Engl J Med. 2002;347(21):1678-1686. doi: 10.1056/NEJMsa020080 [DOI] [PubMed] [Google Scholar]
- 33.Faridi KF, Peterson ED, McCoy LA, Thomas L, Enriquez J, Wang TY. Timing of first postdischarge follow-up and Medication adherence after acute myocardial infarction. JAMA Cardiol. 2016;1(2):147-155. doi: 10.1001/jamacardio.2016.0001 [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
eFigure. Trends in Number of Uninsured and Medicaid-Insured Patients Hospitalized for Acute Myocardial Infarction in Expansion States (Panel A) and Non-Expansion States (Panel B)
eTable 1. Categorization of Medicaid Expansion vs. Non-Expansion States
eTable 2. Home Medications and Laboratory Values during Hospitalization in the Pre- and Post-Expansion Periods by State Expansion Status
eTable 3. Baseline Patient Characteristics in the Pre- and Post-Expansion Periods by State Expansion Status (Lowest Income Quintile Cohort)
eTable 4. Home Medications and Laboratory Values during Hospitalization in the Pre- and Post-Expansion Periods by State Expansion Status (Lowest Income Quintile Cohort)
eTable 5. Association of Medicaid Expansion with Quality of Care and Diagnostic/Therapeutic Interventions by State Expansion Status (Lowest Income Quintile Cohort)
eTable 6. Association of Medicaid Expansion with In-Hospital Outcomes by State Expansion Status (Lowest Income Quintile Cohort)
