Disparities in amputation in patients with peripheral arterial disease

Background:

To describe peripheral arterial disease-related amputation as a marker for health disparities.

Introduction

Peripheral arterial disease (PAD) is a common and debilitating manifestation of cardiovascular disease that impairs blood flow to the lower extremities. Chronic limb-threatening ischemia (CLTI), formerly known as critical limb ischemia, is the most severe manifestation of PAD and encompasses all patients with arterial insufficiency and symptoms of ischemic pain at rest or tissue loss (ie, ulcerations, wounds, or gangrene).^1-3 Diabetes mellitus (DM) is also an important risk factor to consider when discussing lower extremity amputation and can often be difficult to separate from PAD as a cause. Patients with poorly controlled DM develop muscular, sensory, immunologic, and varying degrees of ischemic changes that make them high risk for developing foot complications such as ulcers, and subsequently, amputation (Fig 1). Although patients with DM alone are also at risk for amputation, patients with PAD and DM combined are at highest risk, and are also included in the umbrella term CLTI.⁴ CLTI leads to major (above the ankle) lower extremity amputation in more than 20% of patients and affects more than 2 million people in the United States.^5-6

Fig 1.

The “stairway to amputation” details the cascade of events that occur in the setting of uncontrolled diabetes that lead to amputation. From Armstrong DG, Wrobel J, Robbins JM. Guest editorial: are diabetes-related wounds and amputations worse than cancer? Int Wound J. 2007;4:286–287. (Image reproduced with the permission of David G. Armstrong, DPM, MD, PhD).

Amputation as a marker for health disparities

Amputation is a devastating, but preventable complication of CLTI and DM. A foot ulcer precedes 85% of amputations⁷ and can be treated with timely podiatric and vascular intervention.⁸ Unfortunately, up to 50% of CLTI patients do not even have an attempt at revascularization before undergoing limb amputation.^9,10 Amputation also serves as a marker for severe and poorly managed cardiovascular disease. For instance, 50% to 74% of CLTI patients who undergo amputation die in 5 years owing to cardiac or cerebrovascular complications,^11,12 a prognosis worse than most forms of cancer. As an indicator for barriers related to access to, and quality of health care, amputation rates have been used increasingly as a metric for quality of care and health care disparities by agencies at multiple levels. Healthy People, the federal framework for developing national objectives to improve the health of all Americans, has been tracking disparities in DM-related amputation for decades and has focused on reducing amputations as one of its objectives for the 2020 and 2030 cycle.¹³

Race, ethnicity, sex, and positionality in research

The authors acknowledge that race and ethnicity are not biologic categories, but rather a powerful social construct that has often been arbitrarily assigned to certain individuals throughout history.^14,15 It is the luxury of those in a position of power to define and classify the identities of others and this is a reality that researchers must understand when engaging in disparities work. With this understanding, the authors have chosen to use the standards set by the US Office of Management and Budget’s categorization system for race¹⁶ as a guideline for the nomenclature used in this article, however we have also introduced additional terms related to Hispanic/Latino/a/x ethnicity.¹⁷ This is not meant to be the final word on these categories, but is rather meant to explain the rationale behind our choices, and to welcome continued discussion on this ever-evolving topic.

The authors would also like to emphasize the importance of positionality in all aspects of research. Positionality, the understanding that one’s own race/ethnicity, cultural background, skin color, sexual orientation, ability, and sex, affects the relationships to systems of power and the perspective on the world,¹⁸ is a reality that should be reflected upon as an integral component of the methodology and interpretation of all areas of research, including clinical and basic science. Reflexivity, or the awareness and examination of one’s own positionality and its effects on research is critical,¹⁹ and we believe that this should be declared in the methodology section of health disparities research as a matter of course. As such, the authors of this article identify as cis-gendered White women.

Amputation Disparities

Multiple studies have identified variation in amputation risk based on socioeconomic, racial, ethnic, and geographic (rural/urban) status.^20-26 Although the risk for amputation is highest in communities with higher levels of DM, cardiovascular disease, and tobacco use, it is also disproportionately higher in communities affected by high economic hardship and chronic external stressors.²⁷ These findings further illustrate the role of amputation as a marker for health disparities and social inequities in this country.

Race and ethnicity related disparities

There is a significant body of literature describing racial and ethnic disparities in amputation rates for CLTI and DM,^20,28-40 and although it is often argued that the increased risk of race/ethnicity cannot be separated from confounders such as socioeconomic status, numerous studies have identified that even after controlling for risk factors such as socioeconomic status, co-morbidities and advanced disease, Black and Latino/a/x patients are more likely to undergo major amputation for CLTI/DM than Whites.^{20,26,28,31,34-36,39} Similar findings have been reported in Native American populations.^41,42 More troubling, there is ample evidence to support that race/ethnicity is also an independent predictor for primary amputation (ie, amputation without attempt at revascularization),^{28,31,33,34,36,39,43,44} suggesting that there are other factors at play that have yet to be measured in a meaningful way. These factors may include biologic differences^45,46 (although the authors strongly caution against focusing on race/ethnicity as a biologic variable, as discussed in the previous section), other sources of structural inequities^45,47 and implicit bias.⁴⁸

Geographic disparities and intersectionality

Rural populations have been increasingly identified as an at-risk group for health disparities. Studies suggest that rural patients undergo amputation at rates 51.3% higher than do nonrural patients⁴⁹ and there is data to support that heavily rural areas have higher amputation rates compared with the rest of the country.^24,25,50 A potential explanation for these findings is that rural patients tend to be medically underserved and deal with significant physical and cultural barriers to accessing quality care. In addition, rural populations tend to be older, more economically depressed, and have higher levels of chronic disease and riskier health behaviors than their urban counterparts.⁵¹ It is interesting to note, however, that even when controlling for comorbidities and other risk factors, studies have demonstrated that geographic variation in amputation risk continues to exist (Fig 2),²⁴ further reinforcing the hypothesis that there are other variables at play that we have yet to understand.

Fig 2.

County and ZIP code-level model-fitted relative risk estimates for major and minor amputation in the state of West Virginia, adjusting for covariates. From Minc SD, Hendricks B, Misra R, et al. Geographic variation in amputation rates among patients with diabetes and/or peripheral arterial disease in the rural state of West Virginia identifies areas for improved care. J Vasc Surg. 2020;71:1708–1717.e5.

Finally, there is literature that points to the effect of intersectionality in amplifying risk for amputation. Intersectionality is the theory that individuals’ multiple identities within social systems compound and exacerbate experiences of ill health.^52,53 Examples of the effect of intersectionality in amputation disparities include findings that rural Black patients have a higher risk for primary amputation than their urban Black counterparts⁴⁴ and that Black women are at significantly higher risk for amputation than Black men.⁵⁴

Approaches to Addressing CLTI-Related Amputation Disparities

Although surgeons tend to treat patients after they have developed limb-threatening complications from poorly controlled cardiovascular diseases and DM, it is necessary to act more aggressively earlier in the disease process to reduce the rate of amputations. PAD and CLTI remain frequently underdiagnosed, owing to lack of physician⁵⁵ and patient⁵⁶ awareness. Recognizing the importance of primary prevention, the Society for Vascular Surgery has established a Population Health Task Force with the mission to “explore the strategic role of vascular surgery in achieving patient-focused, value-based multidisciplinary delivery systems that address vascular population health with a focus on vascular health disparities.” The American College of Surgeons and the National Institutes of Health have also reinforced the imperative for surgeons to act as leaders in comprehensive population health conversations with the intent to dismantle disparities and to improve healthcare quality and equity for surgical patients.⁵⁷

Even if participating in these initiatives or performing disparities research, it can be challenging to know how to effect change and address disparities locally. Some ideas to address local disparities include, but are not limited to: (1) working with local researchers, public health experts and community members to gain an accurate understanding of the patterns of disease and disparities in your community and disseminating that information to your community at all levels; (2) getting involved in focused screening and education for PAD, diabetic foot care, and smoking cessation; (3) building a culturally diverse, multispecialty limb salvage team that is reflective of the community it treats; (4) starting an outreach clinic in an underserved area near your practice in order to position vascular surgical care closer to those in the greatest need; (5) actively working to improve rates of women, non-Whites and other underrepresented groups recruited to clinical trials; and (6) advocating for the needs of your community and patient population at the hospital, local, state and federal levels, with the understanding that underserved communities require greater resource allocation and attention than others in order to achieve true health equity.

In conclusion, disparities in amputation in patients with CLTI/DM have persisted for decades and there is no sign of abatement. Currently, more than 500,000 people in the United States live with a major limb amputation owing to CLTI, and this number is projected to double by 2050.⁹ Surgeons play a key role in addressing disparities in vascular care, particularly as it pertains to limb salvage. Surgeons should commit to working with other physicians and their communities to improve comprehensive vascular care to reduce the rate of limb amputation for all.