Enrollment Obstacles in a Randomized Controlled Trial: A Performance Survey of Enrollment in BEST-CLI Sites

Below-the-Knee Endovascular Revascularization: A Position Statement

Patients with chronic limb-threatening ischemia, the terminal stage of peripheral artery disease, are frequently afflicted by below-the-knee disease. Although all patients should receive guideline-directed medical therapy, restoration of inline flow is oftentimes necessary to avoid limb loss. Proper patient selection and proficiency in endovascular techniques for below-the-knee revascularization are intended to prevent major amputation and promote wound healing. This review, a consensus among an international panel of experienced operators, provides guidance on these challenges from an endovascular perspective and offers techniques to navigate this complex disease process.

Contextualizing the BEST-CLI Trial Results in Clinical Practice

Background

Chronic limb-threatening ischemia (CLTI) is associated with poor long-term outcomes. Although prompt revascularization is recommended, the optimal revascularization strategy remains uncertain. The BEST-CLI trial compared endovascular and open surgical revascularization for CLTI, but the generalizability of this study to the clinical population with CLTI has not been evaluated.

Methods

We included Medicare beneficiaries aged 65-85 years with CLTI who underwent revascularization and would be eligible for enrollment in BEST-CLI between 2016 and 2019. The primary exposure was type of revascularization (endovascular vs autologous graft [cohort 1] vs nonautologous graft [cohort 2]), and the primary outcome was a composite of major adverse limb events (MALE) and death. MALE included above-ankle amputation and major intervention, which was defined as new bypass of index limb, thrombectomy, or thrombolysis.

Results

A total of 66,153 patients were included in this study (10,125 autologous grafts; 7867 nonautologous grafts; 48,161 endovascular). Compared with those enrolled in BEST-CLI cohort 1, patients in this study were older (mean age, 73.5 ± 5.7 vs 69.9 ± 9.9 years), more likely to be female (38.3% [22,340/58,286] vs 28.5% [408/1434]), and presented with more comorbidities. Endovascular operators for the study population vs BEST-CLI cohort 1 were less likely to be surgeons (55.9% [26,924/48,148] vs 73.0% [520/708]) and more likely to be cardiologists (25.5% [5900/48,148] vs 14.5% [103/78]). When assessing long-term outcomes, the crude risk of death or MALE in this cohort was higher with surgery (56.6% autologous grafts vs 42.6% BEST-CLI cohort 1 at a median of follow-up 2.7 years; 51.6% nonautologous grafts vs 42.8% BEST-CLI cohort 2 at a median follow-up of 1.6 years) but similar with the endovascular cohort (58.7% Medicare vs 57.4% cohort 1 at 2.7 years; 47.0% Medicare vs 47.7% cohort 2 at 1.6 years). Of those who received endovascular treatment, the risk of incident major intervention was less than half in this cohort compared with the trial cohort (10.0% Medicare vs 23.5% cohort 1 at 2.7 years; 8.6% Medicare vs 25.6% cohort 2 at 1.6 years), although technical endovascular failures were not captured.

Conclusions

These results suggest that the findings of the BEST-CLI trial may not be applicable to the entirety of the Medicare population of patients with CLTI undergoing revascularization.

Understanding Study Drug Discontinuation Through EUCLID

Introduction

Disparities in the care and outcomes of peripheral artery disease (PAD) have been well-established. In part this is due to disparities in enrollment of PAD trial cohorts. However, less attention has been paid to non-random protocol non-adherence after enrollment, which may lead to inaccurate estimates of treatment effects and reduce generalizability of study results. We aimed to ascertain characteristics associated with premature study drug discontinuation in a PAD cohort.

Methods

Using data from EUCLID (Examining Use of Ticagrelor in Peripheral Artery Disease), factors associated with study drug discontinuation were assessed using univariable and multivariable Cox proportional hazards models with time to study drug discontinuation as the outcome of interest. Relationships between study drug discontinuation and major adverse cardiovascular events (MACE; cardiovascular death, myocardial infarction, ischemic stroke), major adverse limb events (MALE; acute limb ischemia, major amputation, and lower extremity revascularization), and all-cause hospitalization were assessed.

Results

Of 13,842 eligible EUCLID participants, 3,886 (28.1%) prematurely and permanently discontinued study drug over a maximum follow-up of 42 months (annualized rate of 13.2 discontinuations per 100 patient-years). In a multivariable model, premature study drug discontinuation was associated with older age (aHR 1.16, 95%CI 1.14–1.19), eligibility based on prior lower extremity revascularization rather than ABI/TBI criteria (aHR 1.14, 95%CI 1.06–1.23), CLI status (aHR 1.23, 95%CI 1.06–1.42), COPD (aHR 1.36, 95%CI 1.24–1.49), and geographic region. In a multivariable analysis, study drug discontinuation was significantly associated with MACE (aHR 3.27, 95%CI 2.90–3.67, p < 0.001), MALE (aHR 1.84, 95%CI 1.63–2.07, p < 0.001), and all-cause hospitalization (aHR 2.37, 95%CI 2.21–2.54) following study drug discontinuation.

Conclusions

This analysis of EUCLID demonstrates that premature, permanent discontinuation of study drug is relatively common in more than a quarter of PAD patients, is unevenly distributed based on geography and other baseline characteristics, and is associated with worse outcomes in a clinical trial context. Study teams leading future PAD trials may want to address the possibility of study drug discontinuation prospectively, as a proactive approach may help investigators to maintain study cohort diversity and representativeness without sacrificing power and precision.

A systematic review of patient-reported outcome measures patients with chronic limb-threatening ischemia

Chronic limb-threatening ischemia (CLTI) causes significant morbidity with profound negative effects on health-related quality of life. As the prevalence of peripheral artery disease and diabetes continue to rise in our aging population, the public health impact of CLTI has escalated. Patient-reported outcome measures (PROMs) have become common and important measures for clinical evaluation in both clinical care and research. PROMs are important for the measurement of clinical effectiveness and cost effectiveness and for shared decision-making on treatment options. However, the PROMs used to describe the experience of patients with CLTI are heterogeneous, incomplete, and lack specific applicability to the underlying disease processes and diverse populations. For example, certain PROMs exist for patients with extremity wounds, and other PROMs exist for patients with pain, and still others exist for patients with vascular disease. Despite this multiplicity of tools, no single PROM encompasses all of the components necessary to describe the experiences of patients with CLTI. This significant unmet need is evident from both published reports and contemporary large-scale clinical trials in the field. In this systematic review, we review the current use of PROMs for patients with CLTI in clinical practice and in research trials and highlight the gaps that need to be addressed to develop a unifying PROM instrument for CLTI.

Participation in a Chronic Limb Threatening Ischemia Randomized Trial Is Inversely Correlated With Regional Amputation Rate in Limb Threatening Ischemia Patients

OBJECTIVE

The National Health Service demonstrated that regions of the United Kingdom with the highest number of patients enrolled in research studies had the lowest risk-adjusted mortality when patients were admitted to the hospital. Our goal was to investigate if this correlation was evident for patients with chronic limb threatening ischemia (CLI) treated in the United States (US). Accordingly, we examined correlations among sites participating in the Best Endovascular versus best Surgical Therapy in patients with Critical (BEST-CLI) trial, a multicenter, National Institute of Health-sponsored, international randomized controlled trial (RCT) comparing revascularization strategies in patients with CLI, and regional rates of major amputation from CLI.

METHODS

We measured regional participation in the BEST-CLI trial by evaluating trial participation and enrollment rosters. To determine regional rates of lower limb amputation, we queried the Medicare database (2007-2016) for patients with concurrent peripheral arterial disease (PAD) and diabetes, then assessed how many had lower extremity amputations. Correlation of regional amputation rates with distribution of BEST-CLI sites in four US geographical regions was calculated using Pearson's correlation coefficients. Simple regression equations were used to calculate the significance of these correlation coefficients.

RESULTS

Of 9,231,909 CLI patients, 342,406 underwent amputation in the Medicare dataset. Amputation rates per 1000 CLI patients differed by region (South 40.42, Midwest 40.12, West 34.81, Northeast 31.14). There were 116 US vascular centers, selected by volume and expertise that participated in BEST-CLI with the following distribution: South (n = 30, 26%), Midwest (n = 26, 22%), West (n = 29, 25%), and Northeast (n = 31, 27%). There was a negative correlation between the number of amputations per 1000 for Medicare CLI patients with diabetes and PAD and the number of BEST-CLI sites in the region which trended toward significance (Pearson R= -0.61, P = 0.39).

CONCLUSIONS

Amputation rate among Medicare CLI patients is inversely correlated with US BEST-CLI site distribution. Higher participation in clinical research, especially within large RCTs, may be a marker of optimal PAD management.

Bench-to-Bedside in Vascular Medicine: Optimizing the Translational Pipeline for Patients With Peripheral Artery Disease

Peripheral arterial disease is a growing worldwide problem with a wide spectrum of clinical severity and is projected to consume >$21 billion per year in the United States alone. While vascular researchers have brought several therapies to the clinic in recent years, few of these approaches have leveraged advances in high-throughput discovery screens, novel translational models, or innovative trial designs. In the following review, we discuss recent advances in unbiased genomics and broader omics technology platforms, along with preclinical vascular models designed to enhance our understanding of disease pathobiology and prioritize targets for additional investigation. Furthermore, we summarize novel approaches to clinical studies in subjects with claudication and ischemic ulceration, with an emphasis on streamlining and accelerating bench-to-bedside translation. By providing a framework designed to enhance each aspect of future clinical development programs, we hope to enrich the pipeline of therapies that may prevent loss of life and limb for those with peripheral arterial disease.

BEST Endovascular Versus Best Surgical Therapy in Patients with Critical Limb Ischemia (BEST-CLI) Trial

The Best Endovascular versus Best Surgical Therapy in Patients with Critical Limb Ischemia trial (BEST-CLI) is an international, prospective, multicentre, multidisciplinary and pragmatic, open-label, superiority-based, comparative-effectiveness randomised controlled trial designed to address the knowledge gap in choosing the appropriate therapy for the treatment of critical limb ischaemia (CLI). This study compares the effectiveness of the best available surgical treatment with the best available endovascular treatment in adults with CLI who are eligible for both treatment options. The study has completed its enrolment phase and patients included in the study are currently being followed up to 50 months. Results of the study promise to provide us with answers to several questions regarding treatment options for patients with CLI, more recently referred to as chronic limb-threatening ischaemia.

WITHDRAWN: One-Year Freedom from Amputation, Survival, and Cost of Care following Tibial and Pedal Endovascular Interventions for Critical Limb Ischemia: The Role of Atherectomy and Drug-Eluting Stents

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