Sage Journals: Discover world-class research

Abstract

Background: In 2014, the Affordable Care Act Medicaid Expansion (ME) increased Medicaid eligibility for adults with an income level up to 138% of the federal poverty level. In this study, we examined the impact of ME on mortality and amputation in patients with peripheral artery disease (PAD). Methods: The 100% MedPAR and Part-B Carrier files from 2011 to 2018 were queried to identify all fee-for-service Medicare beneficiaries with PAD using International Classification of Diseases codes. Our primary exposure was whether a state had adopted the ME on January 1, 2014. Our primary outcomes were the change in all-cause 1-year mortality and leg amputation. We used a state-level difference-in-differences (DID) analysis to compare the rates of the primary outcomes among patients who were in states (including the District of Columbia) who adopted ME (n = 25) versus those who were in states that did not (n = 26). We performed a subanalysis stratifying by sex, race, region, and dual-eligibility status. Results: Over the 8-year period, we studied 37,743,929 patients. The average unadjusted 1-year mortality decreased from 2011 to 2018 in both non-ME (9.5% to 8.7%, p < 0.001) and ME (9.1% to 8.3%, p < 0.001) states. The average unadjusted 1-year amputation rate did not improve in either the non-ME (0.86% to 0.87%, p = 0.17) or ME (0.69% to 0.69%, p = 0.65) states. Across the entire cohort, the DID model revealed that ME did not lead to a significant change in mortality (p = 0.15) or amputation (p = 0.34). Conclusion: Medicaid Expansion was not associated with reduced mortality or leg amputation in Medicare beneficiaries with PAD.

Keywords

amputation Medicaid Expansion mortality peripheral artery disease (PAD)population health

Background

Peripheral artery disease (PAD) affects 12–20% of Americans over 60 years of age.¹ The most severe form of PAD, chronic limb-threatening ischemia, has a 20–30% risk of lower-extremity amputation.^2,3 Moreover, individuals who suffer limb loss have up to 50% 1-year mortality,⁴ and the care of patients with major amputations is estimated to cost more than $9 billion (USD) annually.⁵ Patients with PAD face significant socioeconomic barriers to health care, often lack healthcare insurance, and have difficulty accessing the healthcare system – all of which can lead to a higher risk of amputation.^6,7 In particular, Medicare beneficiaries with PAD also face significant socioeconomic barriers due to incomplete or partial coverage.⁸

To improve healthcare coverage for at-risk adults, in 2014 the Affordable Care Act (ACA) was enacted, which expanded Medicaid eligibility and led to an expansion in the number of dual Medicare/Medicaid eligible individuals. As a result, adults with an income level up to 138% of the federal poverty level became eligible for the Medicaid Expansion (ME) coverage, leading to an overall decline in the uninsured population by 46.5% in 2016.⁹ This improved coverage led to an increase in the prescription of evidence-based cardiovascular medications, including statins, antihypertensives, and antihyperglycemic agents.^10,11 Not all states adopted ME, but those states that did saw a significant decline in cardiovascular mortality compared to nonexpansion states, especially those deaths attributable to hypertensive heart disease and congestive heart failure.^12,13

However, it is unclear whether ME has led to concomitant improvements in outcomes for patients with PAD. Published reports on this topic demonstrate conflicting results. ME appears to have improved access to peripheral vascular interventions,¹⁴ but its impact on mortality and lower-extremity amputation is not well described. Elucidating whether ME has led to improved outcomes among patients with PAD would serve to inform resource allocation for targeted health policy interventions for this at-risk group. Therefore, the aim of this study was to measure the impact of ME on mortality and leg amputations among Medicare beneficiaries with PAD.

Methods

Data source and study population

We studied Medicare beneficiaries from 2011 through 2018. We used the 100% sample MedPAR (inpatient) and Part-B (outpatient) Carrier files from 2011 to 2018 and queried them to identify all fee-for-service Medicare beneficiaries during that interval. Next, we applied a list of International Classification of Diseases, Ninth Revision and Tenth Revision codes derived in prior work to identify beneficiaries with a diagnosis of PAD (online supplemental material).^15
–17 We then limited the cohort to fee-for-service beneficiaries who met the following criteria: (a) coverage for at least 1 year during the interval; (b) US residents; (c) age 65 years or older; and (d) no missing data on mortality (online Supplemental Figure 1). The Dartmouth-Hitchcock Institutional Review Board approved the study and waived the need for consent.

Exposure

Our primary exposure was whether or not a state had adopted ME on January 1, 2014 (online Supplemental Table 1). States, including the District of Columbia, that adopted ME after this time were included in the sensitivity analysis listed below.

Primary outcomes

Our primary outcomes were change in 1-year all-cause mortality, and any leg amputation (major and minor) over the course of the study (2011–2018). We determined vital status using the Medicare Master Beneficiary Summary File. We defined leg amputation using a list of Healthcare Common Procedure Coding System codes that have been derived by our group and others (online Supplemental Figure 1).^15
–17

Statistical analysis

We described continuous variables using means and SDs and compared them with t-tests. We described categorical variables as percentages and compared them with the chi-squared test. We calculated the percent of the cohort suffering mortality for each month of the study interval. We then compared these percentages across the exposure groups. We performed a state-level difference-in-differences (DID) analysis to compare the risk of mortality among beneficiaries from states who adopted ME versus those from states that did not adopt it. The estimates were adjusted for age, sex, race, geography (rural vs urban based on rural–urban commuting area codes), and comorbidities (atrial fibrillation, congestive heart failure, ischemic heart disease, hypertension, hyperlipidemia, history of transient ischemic attack or stroke, diabetes, anemia, hip fracture, dementia, chronic obstructive pulmonary disease, chronic kidney disease, malignancy, and obesity). We then repeated these analyses for the outcome of leg amputation. We conducted prespecified subanalyses of patients stratified by sex, race, geographical area (Northeast, Midwest, South, and West), Medicare/Medicaid dual eligibility, and after excluding states who adopted ME after April 1, 2014. We provided two-sided p-values and those below 0.05 were considered statistically significant.

Results

Characteristics of the cohort

We included 37,743,929 patients over the 8-year period, 18,587,572 in ME states and 19,156,357 in non-ME states (Table 1). Patients in ME states were older (mean ± SD age in ME states: 78.7 ± 8.4 vs non-ME states: 78.1 ± 8.2 years, p < 0.0001), more likely to be women (ME states: 55.1% vs non-ME states: 53.8%, p < 0.0001), Hispanic (ME states: 5.4% vs non-ME states: 4.4%, p < 0.0001), residing in an urban area (ME states: 89.1% vs non-ME states: 84.1%, p < 0.0001), and dual eligibile for both Medicare and Medicaid coverage (ME states: 23.3% vs non-ME states: 20.7%, p < 0.0001). Compared to patients in ME states, those in non-ME states were more likely to have a history of congestive heart failure, ischemic heart disease, hypertension, hyperlipidemia, chronic obstructive pulmonary disease, ischemic stroke or transient ischemic attack, and obesity (all p < 0.0001).

Table 1.

Baseline characteristics of patients in states with versus without Medicaid Expansion.

Characteristic	Expansion states(n = 25)	Nonexpansion states(n = 26)	p-value
Characteristic	N = 18,587,572	N = 19,156,357	p-value
Age, years, mean ± SD	78.7 ± 8.4	78.1 ± 8.2	< 0.0001
Female sex, %	55.1	53.8	< 0.0001
Race, %
White	82.3	84.4	< 0.0001
Black	7.2	9.2
Hispanic	5.4	4.4
Asian	3.4	0.8
Other	0.9	0.4
American Indian	0.3	0.4
Unknown	0.6	0.4
Rural, %	10.9	15.9	< 0.0001
Dual eligible, %	23.3	20.7	< 0.0001
Comorbidities, %
Atrial fibrillation	18.8	18.5	< 0.0001
CHF	33.0	33.6	< 0.0001
Ischemic heart disease	55.1	58.3	< 0.0001
Diabetes	39.7	39.8	0.07
Hypertension	81.7	83.7	< 0.0001
Hyperlipidemia	65.8	67.1	< 0.0001
Chronic kidney disease	36.4	38.9	< 0.0001
Ischemic stroke / TIA	9.4	9.7	< 0.0001
COPD	22.3	25.0	< 0.0001
Cancer	13.0	12.7	< 0.0001
Obesity	14.9	16.9	< 0.0001
Anemia	43.5	42.1	< 0.0001
Dementia	25.1	25.8	< 0.0001
Hip fracture	2.1	2.1	< 0.0001

CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; TIA, transient ischemic attack.

Mortality in states with Medicaid Expansion (ME) versus non-ME states

The average unadjusted 1-year mortality decreased both in ME states from 9.10% in 2011 to 8.3% in 2018 (p < 0.001), and in non-ME states from 9.5% in 2011 to 8.7% in 2018 (p < 0.001) (Figure 1). Across the entire cohort, the adjusted DID model revealed that ME was not associated with a change in 1-year mortality (p = 0.15). Similar trends were observed when stratified by sex (Figure 2), race (Figure 3), and region (Figure 4). Trends were similar when stratified by dual-eligibility status or excluding states who adopted ME after April 1, 2014.

Figure 1.

One-year mortality and amputation rates in Medicaid-Expansion versus non-Medicaid Expansion states.

Figure 2.

One-year mortality and amputation rates in Medicaid-Expansion versus non-Medicaid Expansion states stratified by sex.

Figure 3.

One-year mortality and amputation rates in Medicaid-Expansion versus non-Medicaid Expansion states stratified by race.

Figure 4.

One-year mortality and amputation rates in Medicaid-Expansion versus non-Medicaid Expansion states stratified by region.

Amputation rates in ME versus non-ME states

The average unadjusted 1-year amputation rates remained unchanged over the study period in both ME states, from 0.69% in 2011 to 0.69% in 2018 (p = 0.65), and in non-ME states from 0.86% in 2011 to 0.87% in 2018 (p = 0.17) (Figure 1). Across the entire cohort, the adjusted DID model revealed that ME was not associated with a change in 1-year amputation (p = 0.34). Similar trends were observed when stratified by sex (Figure 2), race (Figure 3), region (Figure 4), or type of amputation (major vs minor; online Supplemental Figure 2) or excluding states who adopted ME after April 1, 2014. In patients with dual eligibility, the adjusted DID model revealed that 1-year amputation rates decreased significantly in men whereas the ME was associated with a 0.12% (95% CI: 0.02–0.30) decrease in amputation rates (p = 0.03), but no statistically significant difference was noted among women (p = 0.87).

Discussion

In this study of nearly 38 million Medicare beneficiaries with PAD, we found that the implementation of ME at the state level was not associated with a decrease in 1-year mortality or lower-extremity amputation. We found similar trends in subanalyses after stratifying by sex, race, and region. In patients with dual eligibility, ME was associated with a decrease in amputation rates only in men. Our findings build upon the existing evidence by employing a DID modeling technique, which may reduce unmeasured confounding. These findings indicate that though other studies have documented that the ME is associated with improvements in healthcare delivery,^9
–13 these benefits do not appear to lead to measurable improvements in mortality and amputation rates among beneficiaries with PAD.

Signed into law on March 3, 2010, the ACA, a US federal statute, was designed to improve access to health care in people with low socioeconomic status, establish new health insurance marketplaces, and expand Medicaid eligibility for low-income adults.⁹ States implementing ME saw a significantly greater increase in prescriptions of antihyperglycemic medications, including glucagon-like peptide 1 receptor agonists and sodium-glucose cotransporter 2 inhibitors,¹⁰ with a significant reduction in hospitalizations for diabetic ketoacidosis,¹⁸ and improvement in glucose control.¹⁹ Similar trends were seen with cardiovascular prescriptions, including statins, antihypertensives, and P2Y12 inhibitors,¹¹ and with improved access to smoking-cessation treatments.²⁰ Importantly, although a significant increase in antihyperglycemic and cardio-vascular prescriptions was seen in both ME and non-ME states, the number of prescriptions was significantly higher in ME versus non-ME states, as evaluated with DID analysis.^10,11 Moreover, ME has been associated with improvement in hypertension control,¹⁹ and 4 per 100,000 fewer deaths due to cardiovascular mortality,¹³ especially due to hypertensive heart disease and congestive heart failure.¹² Despite improved access to health care, including a significant decrease in the proportion of uninsured hospitalizations for myocardial infarction, stroke, and heart failure in ME states, ME has not been associated with improved in-hospital all-cause mortality.^21
–23

Conversely, published reports of whether ME has led to improvements among patients with PAD have shown conflicting results. ME has been associated with improved access to vascular procedures, including elective lower-extremity revascularization,²⁴ as well as lower in-hospital mortality and 1-year incidence of repeat procedures or major amputation among patients who underwent surgery.¹⁴ The association with amputation is less clear. Although ME was associated with a decreased rate of amputations in Arkansas,²⁵ ME was not associated with a decrease in amputation rates or increased utilization of vascular procedures in New York or Arizona.²⁶ This is consistent with our nationally representative study of patients with PAD in which ME was not associated with a decrease in all-cause mortality or amputation, even when stratified by sex, race, or region.

We performed a subanalysis of patients who had dual eligibility for Medicare and Medicaid, a high-risk subgroup of Medicare patients. One prior study comparing dual-eligible beneficiaries to the general Medicare population undergoing peripheral vascular intervention for critical limb-threatening ischemia found higher rates of major amputation and death among dual-eligible patients.²⁷ This suggests that these patients continue to suffer from delayed diagnosis and treatment, despite improved access to health insurance. We found that in the subset of dual-eligible patients with PAD, ME was not associated with lower mortality, even when stratifying by sex or race. Although ME was not associated with overall lower rates of amputation, men in states with ME saw a decline in rates of amputation compared to men in non-ME states, although this finding was not seen in women. A reason for this finding may be due to the discrepancy in PAD care for men and women, as women are significantly less likely to receive guideline-directed medical therapy²⁸ or undergo revascularization for PAD.²⁹

We found that ME was not associated with improved survival or decreased amputation when stratified by region or by urban/rural area. In prior studies, individuals in rural areas and with lower socioeconomic status had a significantly higher risk of amputation due to PAD compared to those in urban areas and with higher socioeconomic status,^27,30 despite receiving similar care (imaging and medications) after diagnosis of PAD.²⁷ This effect has been shown to be amplified in non-White patients.³¹ This is thought to be due to delayed access to health care due to lack of insurance coverage. In 2008, Oregon introduced a limited expansion of the Medicaid program by randomly choosing 30,000 eligible individuals, providing an opportunity to evaluate health outcomes of individuals with and without ME.³² This experiment resulted in improved access to healthcare services and reduced financial strain equally among the urban and rural populations.³³ After ME was enacted, insurance coverage improved significantly in the rural population, especially among low-income childless adults.³⁴

Our results showing that ME was not associated with reduced mortality or amputation for Medicare beneficiaries indicate that there is further work to be done to improve outcomes among Medicare beneficiaries with PAD. Despite improvement in their access to health care, patients with PAD, compared to other disease processes (i.e., hypertension, diabetes, coronary artery disease), do not appear to have enjoyed the same benefits of improved outcomes. The etiology of these findings is yet to be elucidated but certainly is influenced by the fact that individuals with PAD are less likely to receive secondary prevention therapies compared to those with cardiac disease.³⁵ Importantly, among Medicare beneficiaries undergoing major amputation for chronic limb-threatening ischemia, more than 60% did not undergo an angiogram or revascularization in a year preceding the amputation.³⁶ This suggests that a multifaceted approach is necessary to improve outcomes in patients in PAD – not only at the policy level but also at the individual health system level. Focus on timely diagnosis of PAD and institution of secondary prevention measures that are known to improve outcomes is paramount.

Limitations

Our study has several limitations. As Medicare data are designed for billing, it can be difficult to identify true clinical events from claims codes. However, we have previously validated claims data directly against patient chart review and telephone interviews in several studies.^15
–17 Therefore, we believe the results obtained in this analysis should be accurate. Next, the DID analysis is limited by the assumptions imposed on the model. For this case, the assumption is that states who adopt ME offer it to all patients with PAD who are eligible. Given that Medicare billing claims data were used in the analysis, it is reasonable to assume that patients who qualify will have been offered ME to improve billing and reimbursement. Furthermore, this type of analysis is specifically designed to evaluate policy changes over time.³⁷ Additionally, we studied 1-year change in outcomes, which may be too short to see a change in rates of mortality and amputation. Finally, our study did not include patients who were not Medicare eligible (i.e., uninsured patients who received Medicaid as part of ME). However, ME provides dual eligibility for individuals with incomes up to 138% of the federal poverty level, who would receive benefits that may not be otherwise covered by Medicare; or that an individual may not afford.

Conclusions

Medicaid Expansion is not associated with reduced mortality or leg amputation in Medicare beneficiari-es with PAD. Although this policy intervention has improved outcomes for other disease processes, patients with PAD do not appear to have derived the same beneficial impact.

Supplemental Material

sj-docx-1-vmj-10.1177_1358863X241237776 – Supplemental material for The impact of the Affordable Care Act Medicaid Expansion in Medicare beneficiaries with peripheral artery disease

Supplemental material, sj-docx-1-vmj-10.1177_1358863X241237776 for The impact of the Affordable Care Act Medicaid Expansion in Medicare beneficiaries with peripheral artery disease by Stanislav Henkin, Stephen A Kearing, Pablo Martinez-Camblor, Nikolaos Zacharias, Mark A Creager, Michael N Young, Philip P Goodney and Jesse A Columbo in Vascular Medicine

Supplemental Material

sj-jpg-1-vmj-10.1177_1358863X241237776 – Supplemental material for The impact of the Affordable Care Act Medicaid Expansion in Medicare beneficiaries with peripheral artery disease

Supplemental material, sj-jpg-1-vmj-10.1177_1358863X241237776 for The impact of the Affordable Care Act Medicaid Expansion in Medicare beneficiaries with peripheral artery disease by Stanislav Henkin, Stephen A Kearing, Pablo Martinez-Camblor, Nikolaos Zacharias, Mark A Creager, Michael N Young, Philip P Goodney and Jesse A Columbo in Vascular Medicine

Supplemental Material

sj-jpg-2-vmj-10.1177_1358863X241237776 – Supplemental material for The impact of the Affordable Care Act Medicaid Expansion in Medicare beneficiaries with peripheral artery disease

Supplemental material, sj-jpg-2-vmj-10.1177_1358863X241237776 for The impact of the Affordable Care Act Medicaid Expansion in Medicare beneficiaries with peripheral artery disease by Stanislav Henkin, Stephen A Kearing, Pablo Martinez-Camblor, Nikolaos Zacharias, Mark A Creager, Michael N Young, Philip P Goodney and Jesse A Columbo in Vascular Medicine

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

This study was supported by the Department of Medicine Scholarship Enhancement in Academic Medicine Award Pro-gram, Dartmouth-Hitchcock Medical Center. Dr Columbo was supported by the NIH/NHLBI (award number: K08HL165087) and the Society for Vascular Surgery.

Supplementary material

The supplementary material is available online with the article.

ORCID iDs

Stanislav Henkin

Mark A Creager

Jesse A Columbo

References

Tsao

Aday

Almarzooq

, et al. Heart disease and stroke statistics–2023 update: A report from the American Heart Association. Circulation 2023; 147: e93–e621.

Marston

Davies

Armstrong

, et al. Natural history of limbs with arterial insufficiency and chronic ulceration treated without revascularization. J Vasc Surg 2006; 44: 108–114.

Nehler

Duval

Diao

, et al. Epidemiology of peripheral arterial disease and critical limb ischemia in an insured national population. J Vasc Surg 2014; 60: 686–695.e2.

Jones

Patel

Dai

, et al. High mortality risks after major lower extremity amputation in Medicare patients with peripheral artery disease. Am Heart J 2013; 165: 809–815.e1.

Chan

Carruthers

. Incidence, prevalence, costs, and impact on disability of common conditions requiring rehabilitation in the United States: Stroke, spinal cord injury, traumatic brain injury, multiple sclerosis, osteoarthritis, rheumatoid arthritis, limb loss, and back pain. Arch Phys Med Rehabil 2014; 95: 986–995.e1.

Eslami

Zayaruzny

Fitzgerald

. The adverse effects of race, insurance status, and low income on the rate of amputation in patients presenting with lower extremity ischemia. J Vasc Surg 2007; 45: 55–59.

Giacovelli

Egorova

Nowygrod

, et al. Insurance status predicts access to care and outcomes of vascular disease. J Vasc Surg 2008; 48: 905–911.

US Department of Health & Human Services (HHS). Beneficiaries Dually Eligible for Medicare & Medicaid, https://www.cms.gov/outreach-and-education/medicare-learning-network-mln/mlnproducts/downloads/medicare_beneficiaries_dual_eligibles_at_a_glance.pdf (2022, accessed Aug 22, 2023).

Uberoi

Finegold

Gee

. Health Insurance Coverage and the Affordable Care Act, 2010–2016, https://aspe.hhs.gov/sites/default/files/private/pdf/187551/ACA2010-2016.pdf (2016, accessed July 10, 2021).

10.

Sumarsono

Buckley

Machado

, et al. Medicaid expansion and utilization of antihyperglycemic therapies. Diabetes Care 2020; 43: 2684–2690.

11.

Sumarsono

Lalani

Segar

, et al. Association of Medicaid expansion with rates of utilization of cardiovascular therapies among Medicaid beneficiaries between 2011 and 2018. Circ Cardiovasc Qual Outcomes 2021; 14: e007492.

12.

Khan

Lloyd-Jones

Carnethon

Pool

. Medicaid expansion and state-level differences in premature cardiovascular mortality by subtype, 2010–2017. Hypertension 2020; 76: e37–e38.

13.

Khatana

SAM

Bhatla

Nathan

, et al. Association of Medicaid Expansion with cardiovascular mortality. JAMA Cardiol 2019; 4: 671–679.

14.

Eslami

Dakour-Aridi

Avgerinos

, et al.; Vascular Quality Initiative. Impact of Medicaid Expansion of the Affordable Care on the outcomes of lower extremity bypass for patients with peripheral artery disease in the Vascular Quality Initiative database. Ann Surg 2019; 270: 647–655.

15.

Barnes

Eid

Creager

Goodney

. Epidemiology and risk of amputation in patients with diabetes mellitus and peripheral artery disease. Arterioscler Thromb Vasc Biol 2020; 40: 1808–1817.

16.

Goodney

Tarulli

Faerber

, et al. Fifteen-year trends in lower limb amputation, revascularization, and preventive measures among Medicare patients. JAMA Surg 2015; 150: 84–86.

17.

Goodney

Travis

Nallamothu

, et al. Variation in the use of lower extremity vascular procedures for critical limb ischemia. Circ Cardiovasc Qual Outcomes 2012; 5: 94–102.

18.

Tekin

Saygili

. The association between Medicaid Expansion and diabetic ketoacidosis hospitalizations. Cureus 2022; 14: e30631.

19.

Cole

Kim

Levengood

Trivedi

. Association of Medicaid Expansion with 5-year changes in hypertension and diabetes outcomes at federally qualified health centers. JAMA Health Forum 2021; 2: e212375.

20.

McMenamin

Yoeun

Halpin

. Affordable Care Act impact on Medicaid coverage of smoking-cessation treatments. Am J Prev Med 2018; 54: 479–485.

21.

Wadhera

Bhatt

Wang

, et al. Association of state Medicaid Expansion with quality of care and outcomes for low-income patients hospitalized with acute myocardial infarction. JAMA Cardiol 2019; 4: 120–127.

22.

Akhabue

Pool

Yancy

, et al. Association of state Medicaid expansion with rate of uninsured hospitalizations for major cardiovascular events, 2009–2014. JAMA Netw Open 2018; 1: e181296.

23.

Wadhera

Joynt Maddox

Fonarow

, et al. Association of the Affordable Care Act’s Medicaid Expansion with care quality and outcomes for low-income patients hospitalized with heart failure. Circ Cardiovasc Qual Outcomes 2018; 11: e004729.

24.

Eguia

Baker

Bechara

, et al. The impact of the Affordable Care Act Medicaid Expansion on vascular surgery. Ann Vasc Surg 2020; 66: 454–461.e1.

25.

Duke

Porter

3rd Karim

, et al. Effects of the Affordable Care Act on vascular patient amputation rates in Arkansas. Ann Vasc Surg 2019; 54: 48–53.

26.

Bennett

Matusko

Waljee

, et al. The impact of Medicaid Expansion on utilization of vascular procedures and rates of amputation. J Surg Res 2019; 243: 531–538.

27.

Austin

Chakraborti

Columbo

, et al. Outcomes after peripheral artery disease intervention among Me-dicare–Medicaid dual-eligible patients compared with the general Medicare population in the Vascular Quality Initiative registry. BMJ Surg Interv Health Technol 2019; 1: e000018.

28.

Pabon

Cheng

Altin

, et al. Sex differences in peripheral artery disease. Circ Res 2022; 130: 496–511.

29.

Egorova

Vouyouka

Quin

, et al. Analysis of gender-related differences in lower extremity peripheral arterial disease. J Vasc Surg 2010; 51: 372–378.e1; discussion 378–379.

30.

Eid

Mehta

Goodney

. Epidemiology of peripheral artery disease. Semin Vasc Surg 2021; 34: 38–46.

31.

Minc

Goodney

Misra

, et al. The effect of rurality on the risk of primary amputation is amplified by race. J Vasc Surg 2020; 72: 1011–1017.

32.

Baicker

Taubman

Allen

, et al. The Oregon experiment—effects of Medicaid on clinical outcomes. N Engl J Med 2013; 368: 1713–1722.

33.

Allen

Wright

Broffman

. The impacts of Medicaid Expansion on rural low-income adults: Lessons from the Oregon Health Insurance Experiment. Med Care Res Rev 2018; 75: 354–383.

34.

Soni

Hendryx

Simon

. Medicaid Expansion under the Affordable Care Act and insurance coverage in rural and urban areas. J Rural Health 2017; 33: 217–226.

35.

Pande

Perlstein

Beckman

Creager

. Secondary prevention and mortality in peripheral artery disease: National Health and Nutrition Examination Study, 1999 to 2004. Circulation 2011; 124: 17–23.

36.

Secemsky

Kirksey

Quiroga

, et al. Impact of intensity of vascular care preceding major amputation among patients with chronic limb-threatening ischemia. Circ Cardiovasc Interv 2024; 17: e012798.

37.

Dimick

Ryan

. Methods for evaluating changes in health care policy: The difference-in-differences approach. JAMA 2014; 312: 2401–2402.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

0.03 MB

0.05 MB

0.07 MB