Trends of Concomitant Diabetes and Peripheral Artery Disease and Lower Extremity Amputation in US Medicare Patients, 2007 to 2019

BACKGROUND

Previous studies demonstrate geographic and racial/ethnic variation in diagnosis and complications of diabetes and peripheral artery disease (PAD). However, recent trends for patients diagnosed with both PAD and diabetes are lacking. We assessed the period prevalence of concurrent diabetes and PAD across the United States from 2007 to 2019 and regional and racial/ethnic variation in amputations among Medicare patients.

METHODS

Using Medicare claims from 2007 to 2019, we identified patients with both diabetes and PAD. We calculated period prevalence of concomitant diabetes and PAD and incident cases of diabetes and PAD for every year. Patients were followed to identify amputations, and results were stratified by race/ethnicity and hospital referral region.

RESULTS

9 410 785 patients with diabetes and PAD were identified (mean age, 72.8 [SD, 10.94] years; 58.6% women, 74.7% White, 13.2% Black, 7.3% Hispanic, 2.8% Asian/API, and 0.6% Native American). Period prevalence of diabetes and PAD was 23 per 1000 beneficiaries. We observed a 33% relative decrease in annual new diagnoses throughout the study. All racial/ethnic groups experienced a similar decline in new diagnoses. Black and Hispanic patients had on average a 50% greater rate of disease compared with White patients. One- and 5-year amputation rates remained stable at ≈1.5% and 3%, respectively. Native American, Black, and Hispanic patients were at greater risk of amputation compared with White patients at 1- and 5-year time points (5-year rate ratio range, 1.22-3.17). Across US regions, we observed differential amputation rates, with an inverse relationship between the prevalence of concomitant diabetes and PAD and overall amputation rates.

CONCLUSIONS

Significant regional and racial/ethnic variation exists in the incidence of concomitant diabetes and PAD among Medicare patients. Black patients in areas with the lowest rates of PAD and diabetes are at disproportionally higher risk for amputation. Furthermore, areas with higher prevalence of PAD and diabetes have the lowest rates of amputation.

Quality of Life in Patients With Chronic Limb-Threatening Ischemia Treated With Revascularization

BACKGROUND

In the BEST-CLI trial (Best Endovascular Versus Best Surgical Therapy for Patients With Chronic Limb-Threatening Ischemia), a prespecified secondary objective was to assess the effects of revascularization strategy on health-related quality of life (HRQoL).

METHODS

Patients with chronic limb-threatening ischemia were randomized to surgical bypass (Bypass) or endovascular intervention (Endo) in 2 parallel trials. Cohort 1 included patients with single-segment great saphenous vein; cohort 2 included those lacking suitable single-segment great saphenous vein. HRQoL was assessed over the trial duration using Vascular Quality-of-Life (VascuQoL), European Quality-of-Life-5D (EQ-5D), the Short Form-12 (SF-12) Physical Component Summary (SF-12 PCS), SF-12 Mental Component Summary (SF-12 MCS), Utility Index Score (SF-6D R2), and numeric rating scales of pain. HRQoL was summarized by cohort and compared within and between groups using mixed-model linear regression.

RESULTS

A total of 1193 and 335 patients in cohorts 1 and 2 with a mean follow-up of 2.9 and 2.0 years, respectively, were analyzed. In cohort 1, HRQoL significantly improved from baseline to follow-up for both groups across all measures. For example, mean (SD) VascuQoL scores were 3.0 (1.3) and 3.0 (1.2) for Bypass and Endo at baseline and 4.7 (1.4) and 4.8 (1.5) over follow-up. There were significant group differences favoring Endo when assessed with VascuQoL (difference, -0.14 [95% CI, -0.25 to -0.02]; P=0.02), SF-12 MCS (difference, -1.03 [95% CI, -1.89 to -0.18]; P=0.02), SF-6D R2 (difference, -0.01 [95% CI, -0.02 to -0.001]; P=0.03), numeric rating scale pain at present (difference, 0.26 [95% CI, 0.03 to 0.49]; P=0.03), usual level during previous week (difference, 0.26 [95% CI, 0.04 to 0.48]; P=0.02), and worst level during previous week (difference, 0.29 [95% CI, 0.02 to 0.56]; P=0.04). There was no difference between treatment arms on the basis of EQ-5D (difference, -0.01 [95% CI, -0.03 to 0.004]; P=0.12) or SF-12 PCS (difference, -0.41 [95% CI, -1.2 to 0.37]; P=0.31). In cohort 2, HRQoL also significantly improved from baseline to the end of follow-up for both groups based on all measures, but there were no differences between Bypass and Endo on any measure.

CONCLUSIONS

Among patients with chronic limb-threatening ischemia deemed eligible for either Bypass or Endo, revascularization resulted in significant and clinically meaningful improvements in HRQoL. In patients with an available single-segment great saphenous vein for bypass, but not among those without one, Endo was statistically superior on some HRQoL measures; however, these differences were below the threshold of clinically meaningful difference.

Etiology and outcomes of amputation in patients with peripheral artery disease in the EUCLID trial

OBJECTIVE

Amputation remains a frequent and feared outcome in patients with peripheral artery disease (PAD). Although typically characterized as major or minor on the extent of tissue loss, the etiologies and outcomes after amputation by extent are not well-understood. In addition, emerging data suggest that the drivers and outcomes of amputation in patients with PAD may differ in those with and without diabetes mellitus (DM).

METHODS

The EUCLID trial randomized 13,885 patients with symptomatic PAD, including 5345 with concomitant diabetes, to ticagrelor or clopidogrel and followed them for long-term outcomes. Amputations were prospectively reported by trial investigators. Their primary and contributing drivers were adjudicated using safety data, including infection, ischemia, or multifactorial etiologies. Outcomes following major and minor amputations were analyzed, including recurrent amputation, major adverse limb events, adverse cardiovascular events, and mortality. Multivariable logistic regression models were used to identify independent predictors of minor amputations. Analyses were performed overall and stratified by the presence or absence of DM at baseline.

RESULTS

Of the patients randomized, 398 (2.9%) underwent at least one lower extremity nontraumatic amputation, for a total of 511 amputations (255 major and 256 minor) over a median of 30 months. A history of minor amputation was the strongest independent predictor for a subsequent minor amputation (odds ratio, 7.29; 95% confidence interval, 5.17-10.30; P < .001) followed by comorbid DM (odds ratio, 4.60; 95% confidence interval, 3.16-6.69; P < .001). Compared with patients who had a major amputation, those with a minor amputation had similar rates of subsequent major amputation (12.2% vs 13.6%), major adverse limb events (15.1% vs 14.9%), and major adverse cardiovascular events (17.6% vs 16.3%). Ischemia alone was the primary driver of amputation (51%), followed by infection alone (27%), and multifactorial etiologies (22%); however, infection was the most frequent driver in those with DM (58%) but not in those without DM (15%).

CONCLUSIONS

Outcomes after amputation remain poor regardless of whether they are categorized as major or minor. The pattern of amputation drivers in PAD differs by history of DM, with infection being the dominant etiology in those with DM and ischemia in those without DM. Greater focus is needed on the prognostic importance of minor amputation and of the multifactorial etiologies of amputation in PAD. Nomenclature with anatomical description of amputations and eliminating terms "major" or "minor" would seem appropriate.

Trends in patient characteristics and mortality among Medicare patients diagnosed with peripheral artery disease

INTRODUCTION

Peripheral artery disease (PAD) is a well-described risk factor for mortality, but few studies have examined secular trends in mortality over time for patients with PAD. We characterized trends in mortality in patients with PAD in recent years among Medicare patients.

METHODS

We used Medicare claims to identify patients with a new diagnosis code for PAD between January 1, 2006 and December 31, 2018 using International Classification of Diseases (ICD) diagnosis codes. The primary outcome of interest was the 1-year all-cause age-adjusted mortality rate. Our secondary outcome was the 5-year all-cause mortality rate. Multivariable regression was used to identify factors which predict mortality at 1 year.

RESULTS

We identified 4,373,644 patients with a new diagnosis code for PAD during the study period. Between 2006 and 2018, 1-year all-cause age-adjusted mortality declined from 12.6% to 9.9% (p < 0.001). One-year crude all-cause mortality also declined from 14.6% to 9.5% (p < 0.001). Similar results were observed for 5-year age-adjusted mortality rates (40.9% to 35.2%, p < 0.001). Factors associated with increased risk of death at 1 year included age ⩾ 85 years (hazard ratio [HR] 3.030; 95% CI 3.008-3.053) and congestive heart failure (HR 1.86; 95% CI 1.85-1.88). Patients who were regularly dispensed statins, ace-inhibitors, beta-blockers, antithrombotic agents, and anticoagulants all had lower mortality (range OR 0.36; CI 0.35-0.37 for statins to OR 0.60; CI 0.59-0.61 for anticoagulants; all p < 0.001).

CONCLUSION

Among US Medicare patients diagnosed with PAD between 2006 and 2019, 1-year age-adjusted mortality declined by 2.7%. This decline in mortality among patients with PAD occurred in the context of a younger mean age of diagnosis of PAD and improved cardiovascular prevention therapy.

The relationship of regional hemoglobin A1c testing and amputation rate among patients with diabetes

Objective The risk of leg amputation among patients with diabetes has declined over the past decade, while use of preventative measures-such as hemoglobin A1c monitoring-has increased. However, the relationship between hemoglobin A1c testing and amputation risk remains unclear. Methods We examined annual rates of hemoglobin A1c testing and major leg amputation among Medicare patients with diabetes from 2003 to 2012 across 306 hospital referral regions. We created linear regression models to study associations between hemoglobin A1c testing and lower extremity amputation. Results From 2003 to 2012, the proportion of patients who received hemoglobin A1c testing increased 10% (74% to 84%), while their rate of lower extremity amputation decreased 50% (430 to 232/100,000 beneficiaries). Regional hemoglobin A1c testing weakly correlated with crude amputation rate in both years (2003 R = -0.20, 2012 R = -0.21), and further weakened with adjustment for age, sex, and disability status (2003 R = -0.11, 2012 R = -0.17). In a multivariable model of 2012 amputation rates, hemoglobin A1c testing was not a significant predictor. Conclusion Lower extremity amputation among patients with diabetes nearly halved over the past decade but only weakly correlated with hemoglobin A1c testing throughout the study period. Better metrics are needed to understand the relationship between preventative care and amputation.

Therapeutic anticoagulation after index peripheral endovascular intervention in patients with claudication

OBJECTIVE

Antiplatelet agents are commonly used after peripheral endovascular intervention (PVI). However, the effect of full-dose anticoagulation on outcomes after PVI is not well-established. We sought to investigate whether full-dose anticoagulation after PVI is associated with adverse events.

METHODS

We utilized the Vascular Quality Initiative to study patients undergoing index PVI for claudication (2010-2019), stratified by the presence or absence of an anticoagulant on discharge. The primary outcomes were 2-year patency, major adverse limb events (MALE), and mortality. We built a propensity score adjusting for comorbidities and employed inverse probability weighting to estimate the association of anticoagulation with outcomes.

RESULTS

We identified 26,240 patients; 9.1% were discharged on an anticoagulant. Patients receiving any anticoagulation had a significantly higher risk of mortality (adjusted hazard ratio [aHR], 1.61; 95% confidence interval [CI], 1.35-1.92), but not MALE, or patency loss. Patients receiving a vitamin K antagonist had a significantly higher risk of patency loss (aHR, 1.32; 95% CI, 1.09-1.60), MALE (aHR, 1.33; 95% CI, 1.13-1.57), and mortality (aHR, 1.46; 95% CI, 1.27-1.69). Patients on an oral Factor Xa inhibitors had a significantly lower risk of patency loss (aHR, 0.61; 95% CI, 0.41-0.93) but increased mortality (aHR, 1.51; 95% CI, 1.19-1.92).

CONCLUSIONS

Therapeutic anticoagulation after PVI is associated with higher risk of all-cause mortality. Although oral Factor Xa inhibitors are associated with decreased risk of patency loss, vitamin K antagonists are associated with higher risk of patency loss, MALE, and death. Further prospective studies are necessary to study the safety and efficacy of full-dose anticoagulation after PVI.