Rationale and Design of the SAFE-PAD Study

Toward Uniform Case Identification Criteria in Observational Studies on Peripheral Arterial Disease: A Scoping Review

BACKGROUND

The diagnosis of peripheral arterial disease (PAD) is commonly applied for symptoms related to atherosclerotic obstructions in the lower extremity, though its clinical manifestations range from an abnormal ankle-brachial index to critical limb ischemia. Subsequently, management and prognosis of PAD vary widely with the disease stage. A critical aspect is how this variation is addressed in administrative database-based studies that rely on diagnosis codes for case identification. The objective of this scoping review is to inventory the identification strategies used in studies on PAD that rely on administrative databases, to map the pros and cons of the International Classification of Diseases (ICD) codes applied, and to propose a first outline for a consensus framework for case identification in administrative databases.

METHODS

Registry-based reports published between 2010 and 2021 were identified through a systematic PubMed search. Studies were subcategorized on the basis of the expressed study focus: claudication, critical limb ischemia, or general peripheral arterial disease, and the ICD code(s) applied for case identification mapped.

RESULTS

Ninety studies were identified, of which 36 (40%) did not specify the grade of PAD studied. Forty-nine (54%) articles specified PAD grade studied. Five (6%) articles specified different PAD subgroups in methods and baseline demographics, but not in further analyses. Mapping of the ICD codes applied for case identification for studies that specified the PAD grade studied indicated a remarkable heterogeneity, overlap, and inconsistency.

CONCLUSIONS

A large proportion of registry-based studies on PAD fail to define the study focus. In addition, inconsistent strategies are used for PAD case identification in studies that report a focus. These findings challenge study validity and interfere with inter-study comparison. This scoping review provides a first initiative for a consensus framework for standardized case selection in administrative studies on PAD. It is anticipated that more uniform coding will improve study validity and facilitate inter-study comparisons.

Five-Year Independent Patient-Level Mortality Analysis of the Pooled ILLUMENATE Pivotal and EU Randomized Controlled Trials

Background

There is a need to evaluate the latest information regarding a potential late safety signal in patients treated with paclitaxel-coated devices for peripheral artery disease. We evaluated the 5-year all-cause mortality rate of the Stellarex drug-coated balloon (DCB) compared with percutaneous transluminal angioplasty (PTA).

Methods

An independent third-party performed a patient-level meta-analysis of the pooled ILLUMENATE Pivotal and EU randomized controlled trials. The primary outcome was time to death. Kaplan-Meier estimates of all-cause mortality were compared with the log-rank test. Predictors of mortality were assessed with Cox proportional hazard modeling. A blinded clinical events committee adjudicated all serious adverse events (including death). The follow-up was 60 months.

Results

A total of 589 patients were followed for a median of 4.9 years (IQR, 4.8, 5.1 years); 419 were randomized to Stellarex DCB and 170 to PTA. Vital status was obtained for 93.8%. The 5-year Kaplan-Meier estimates of freedom from all-cause death were 80.4% (95% CI, 76.7%-84.3%) in the Stellarex DCB arm versus 80.4% (95% CI, 74.3%-86.5%) in the PTA arm (log-rank, P = .7754). There was no difference in all-cause mortality when stratified by paclitaxel dose terciles. Predictors of mortality included renal insufficiency, reference vessel diameter, age, and lesion length, but not paclitaxel dose nor paclitaxel exposure.

Conclusions

There was no difference in all-cause mortality between the Stellarex DCB and PTA through the final 5-year follow-up window of 2 ILLUMENATE randomized controlled trials. These long-term data build on the previously reported safety of the Stellarex DCB for treating symptomatic femoropopliteal peripheral artery disease.

Association of Clinical Setting With Sociodemographics and Outcomes Following Endovascular Femoropopliteal Artery Revascularization in the United States

BACKGROUND

After the Centers for Medicare and Medicaid Services modified reimbursement rates for outpatient peripheral vascular intervention in 2008 with the intent of improving access to care, providers began to increasingly perform peripheral vascular interventions in privately owned office-based clinics. Little is known about the characteristics of patients treated in this setting and their long-term outcomes as compared with those treated in hospital-based centers.

METHODS

In this retrospective cohort study, Medicare beneficiaries ≥66 years undergoing outpatient femoropopliteal peripheral vascular interventions in office-based clinics and hospital-based centers from 2015 to 2017 were identified. Sociodemographics, comorbidities, and institutional characteristics were compared across sites. Multivariable Cox proportional hazards models were used to estimate the adjusted associations between practice site location and outcomes. The primary outcome was the composite of major amputation or death analyzed through the end of follow-up.

RESULTS

Among 134 869 patients, 29.9% were treated in office-based clinics and 70.1% in hospital-based centers. Patients treated in office-based clinics were more often Black (16.9% versus 11.9%), dually enrolled in Medicaid (26.3% versus 19.6%), and residents of lower-resourced regions (32.6% versus 25.6%). Over a median follow-up time of 800 days (interquartile range, 531-1119 days), patients treated in office-based clinics had reduced risks of major amputation or death compared with outpatients treated in hospital-based centers (hazard ratio, 0.92 [95% CI, 0.89-0.95]). They also had lower adjusted all-cause mortality (hazard ratio, 0.93 [95% CI, 0.90-0.96]), major lower extremity amputation (hazard ratio, 0.84 [95% CI, 0.79-0.89]), and all-cause hospitalization (hazard ratio, 0.86 [95% CI, 0.84-0.88]). These findings persisted after stratification by critical limb ischemia, race, dual enrollment, and regional socioeconomic status, as well as among operators treating patients in both clinical settings.

CONCLUSIONS

In this large nationwide analysis of Medicare beneficiaries, office-based clinics treated a more socioeconomically disadvantaged population compared with hospital-based centers. Long-term outcomes were comparable between locations. As such, these clinics appear to be selecting lower-risk patients for outpatient peripheral vascular interventions, although there remains the possibility of unmeasured confounding.

Outcomes Associated With Peripheral Artery Disease in Myocardial Infarction With Cardiogenic Shock

BACKGROUND

Mortality rates for patients presenting with acute myocardial infarction (AMI) and cardiogenic shock (CS) remain high despite advances in revascularization strategies and mechanical circulatory support (MCS) devices.

OBJECTIVES

This study sought to elucidate the association between comorbid lower extremity peripheral artery disease (PAD) and outcomes in CS and AMI.

METHODS

PAD status was defined in Medicare beneficiaries hospitalized with CS and AMI from October 1, 2015 to June 30, 2018. Primary outcomes ascertained through December 31, 2018 included in- and out-of-hospital mortality. Secondary outcomes included bleeding, amputation, stroke, and lower extremity revascularization. Multivariable regression models with adjustment for confounders were used to estimate risk. Subgroup analyses included patients treated with MCS and those who underwent coronary revascularization.

RESULTS

Among 71,690 patients, 5.9% (N = 4,259) had PAD. Mean age was 77.8 ± 7.9 years, 58.7% were male, and 84.3% were White. Cumulative in-hospital mortality was 47.2%, with greater risk among those with PAD (56.3% vs 46.6% without PAD; adjusted OR: 1.50; 95% CI: 1.40-1.59). PAD patients also had greater risk of in-hospital amputation (1.6% vs 0.2%; adjusted OR: 7.0; 95% CI: 5.26-9.37) and out-of-hospital mortality (67.9% vs 40.7%; adjusted HR: 1.78; 95% CI: 1.67-1.90). MCS was less frequently utilized in PAD patients (21.5% vs 38.6% without PAD; P < 0.001) and was associated with higher mortality, need for lower extremity revascularization, and amputation risk. Findings were consistent in patients who underwent coronary revascularization.

CONCLUSIONS

Among patients presenting with AMI and CS, PAD was associated with worse limb outcomes and survival. In addition to lower MCS utilization rates, those with PAD who received MCS had increased mortality, lower extremity revascularization, and amputation rates.

Longitudinal Assessment of Safety of Femoropopliteal Endovascular Treatment With Paclitaxel-Coated Devices Among Medicare Beneficiaries: The SAFE-PAD Study

IMPORTANCE

Paclitaxel-coated peripheral devices have been associated with increased mortality, yet this harm signal has not been replicated outside of meta-analyses of small trials.

OBJECTIVE

To provide a longitudinal assessment of the safety of femoropopliteal endovascular treatment with peripheral drug-coated devices (DCDs) among Medicare beneficiaries.

DESIGN, SETTING, AND PARTICIPANTS

SAFE-PAD (Safety Assessment of Femoropopliteal Endovascular Treatment With Paclitaxel-Coated Devices) was a retrospective cohort study designed with the US Food and Drug Administration to evaluate the noninferiority of mortality between DCDs and non-drug-coated devices (NDCDs) for femoropopliteal revascularization performed in 2978 inpatient and outpatient facilities in the US from April 1, 2015, through December 31, 2018. Evaluation of the primary outcome was assessed through May 31, 2020. Participants were Medicare fee-for-service beneficiaries 66 years and older with 1 or more years of enrollment prior to femoropopliteal revascularization. Prespecified subgroups included low-risk cohorts, procedure location, disease severity, and device type. Inverse probability weighting was used to account for imbalances of observed characteristics. Sensitivity analyses were used to evaluate the potential influence of unmeasured confounding.

EXPOSURES

Treatment with DCDs vs NDCDs as determined by claims codes during the index procedure.

MAIN OUTCOMES AND MEASURES

The primary outcome was all-cause mortality. Secondary outcomes included repeated hospitalization, repeated lower extremity revascularization, and lower extremity amputation. Falsification end points were acute myocardial infarction, congestive heart failure, and pneumonia.

RESULTS

Of 168 553 patients, 70 584 (41.9%) were treated with a DCD. The mean (SD) age was 77.0 (7.6) years, 75 744 (44.9%) were female, 136 916 of 167 197 (81.9%) were White individuals, 85 880 of 168 553 (51.0%) had diabetes, 82 554 of 168 553 (49.0%) used tobacco, 78 665 of 168 553 (45.7%) had critical limb ischemia (CLI), and 13 296 of 168 553 (7.9%) had a prior amputation. Median follow-up was 2.72 years (interquartile range, 0.87-3.77; longest, 5.16 years). After weighting, the cumulative incidence of all-cause mortality was 53.8% with DCDs and 55.1% with NDCDs (hazard ratio [HR], 0.95; 95% CI, 0.94-0.97; noninferiority P < .001). Cox regression and instrumental variable analyses were consistent with the primary findings. No harm associated with DCDs was observed among subgroups, including those treated with stents (HR, 0.97; 95% CI, 0.95-1.00) or balloons (HR, 0.94; 95% CI, 0.92-0.96), with or without CLI (CLI: HR, 0.95; 95% CI, 0.93-0.97; non-CLI: HR, 0.97; 95% CI, 0.95-0.99), and those within the lowest quartile of total comorbidities (HR, 0.95; 95% CI, 0.92-0.99).

CONCLUSIONS AND RELEVANCE

In this initial report from the SAFE-PAD cohort study, DCDs were found to be noninferior to NCDCs in respect to mortality through a median follow-up of 2.72 years. This finding remained robust in sensitivity analyses and was consistent across prespecified subgroups.

Sex Disparities in Long-Term Mortality after Paclitaxel Exposure in Patients with Peripheral Artery Disease: A Nationwide Claims-Based Cohort Study

BACKGROUND

Randomized controlled trials have reported excess mortality in patients treated with paclitaxel-coated devices versus uncoated devices, while observational studies have reported the opposite. This study aims to determine the underlying factors and cohort differences that may explain these opposite results, with specific focus on sex differences in treatment and outcomes.

METHODS

Multicenter health insurance claims data from a large insurance fund, BARMER, were studied. A homogeneous sample of patients with an index of endovascular revascularization for symptomatic peripheral arterial occlusive disease between 2013 and 2017 was included. Adjusted logistic regression and Cox regression models were used to determine the factors predicting allocation to paclitaxel-coated devices and sex-specific 5-year all-cause mortality, respectively.

RESULTS

In total, 13,204 patients (54% females, mean age 74 ± 11 years) were followed for a median of 3.5 years. Females were older (77 vs. 71 years), and had less frequent coronary artery disease (23% vs. 33%), dyslipidemia (44% vs. 50%), and diabetes (29% vs. 41%), as well as being less likely to have a history of smoking (10% vs. 15%) compared with males. Mortality differences were mostly attributable to the female subgroup who were revascularized above the knee (hazard ratio, HR 0.78, 95% CI: 0.64-0.95), while no statistically significant differences were observed in males.

CONCLUSIONS

This study found that females treated above the knee benefited from paclitaxel-coated devices, while no differences were found in males. Ongoing and future registries and trials should take sex disparities into account.