Treatment of TASC C and D Aortoiliac Lesions

Background:

The treatment of patients with complex aortoiliac disease (AID), classified as Trans-Atlantic Inter-Society consensus II (TASC) class C and D, presents a dilemma for vascular surgeons. Current guidelines recommend either open surgical reconstruction (OR), hybrid repair (HR) combining iliac stenting with femoral endarterectomy, or total endovascular repair (ER). While traditional OR with aortobifemoral bypass (ABF) is associated with excellent long term patency results (85%-90% at five years and 75%-80% at ten years), it is associated with significant perioperative morbidity with some studies citing mortality rates of up to 4-8%. HR has evolved as an attractive minimally invasive alternative to OR, especially if the disease extends to the femoral bifurcation, with the potential advantages of lower perioperative morbidity and a shorter hospital stay. On the other hand, ER offers an attractive alternative with durable results (five-year primary and secondary patency rates ranging from 60% to 86% and 80% to 98%, respectively), especially in less extensive AID. When combined with low perioperative morbidity it makes ER generally preferable for patients with more severe co-morbid conditions. Thus, surgical approaches for extensive AID have changed considerably over the last years, primarily due to increased ER. The advancement of endovascular techniques has led to many trials suggesting that endovascular management of TASC II C and D lesions is a potential alternative treatment to open strategies mainly in the subset of patients with high surgical risk, given the substantially less perioperative morbidity and mortality compared to OR. However, currently, there are no randomized control trials nor large observational trials comparing these treatment option for complex (TASC C and D) aortoiliac lesions. Vascular surgeons are therefore left with a paucity of data to guide decision-making.

Sample size:

To ensure sufficient statistical power to answer hypothetical questions, approximately 900 subjects will be entered into the database. Major adverse limb event rate is the primary endpoint being used to calculate the sample size. Assuming a difference in terms of MALE, 243 patients would be required in each arm to achieve a statistical power of 85% at p=0.05. With three arms (endovascular versus open), assuming a 20% rate of missing data, a total N of 875 patients is required.

Research Design

This is a retrospective study including patients with peripheral arterial disease (all Rutherford stages) treated for TASC C/D aortoiliac lesion from January 1st 2015 until January 1st 2022 in four European countries: Italy, Portugal, Spain, and Serbia.

Procedures Involved:

The study does not involve any patient contact and will not impact the care that patients receive. Data regarding the patients will be compiled and analyzed to accomplish the proposed study objectives. Data collection will include demographic information, patient-related factors, and comorbidities, diagnostic imaging information (describing the morphology of aortoiliac segment and femoral bifurcation), laboratory data, surgical procedure information, complications of the surgery, short- and long-term clinical outcomes.

Multi-Institutional research:

After the data has been collected at a participating institution, the data will be transmitted to online database which will be available only to a central analytic center located at the Clinic for Vascular and Endovascular Surgery/University Clinical Center of Serbia/Medical Faculty, University of Belgrade.

Risks to Subjects:

As this is a retrospective observational study with prospective character, there is no potential for physical risks to subjects. There is a minimal risk of breach of confidentiality that could occur when patient information is collected and analyzed for the proposed study. However, appropriate measures will be taken to minimize the risk as much as possible. All information recorded will be de-identified. This study will abide by all regulations related to protecting human subjects and protected health information.

Potential Benefits to Subjects:

There is no direct benefit to the subjects. However, future patients treated with complex TASC C/D aortoiliac lesions where every treatment option is feasible may benefit from improved care as a result of this study.

Statistics and Data Analysis:

Continuous variables will be described using the median and interquartile range or mean and standard deviation. Categorical variables will be described using frequencies and percentages. Group comparisons will be performed by using the Student t-test or Mann-Whitney U test, as appropriate. Categorical data will be expressed as percentages and were compared using the chi-square test or Fisher exact test. Propensity score analysis will be performed by matching endovascular to OR, HR, and ER group in a 1:1:1 ratio controlling for demographics, baseline comorbidities, and imagining parameters. Differences will be considered statistically significant at p \< 0.05. The cumulative incidences of all-cause mortality, MALE, and primary patency rates will be estimated using the Kaplan-Meier method. Differences between curves will be tested using the log-rank test. Binary outcomes will be evaluated first by univariable methods, with results reported as odds ratio (OR) with 95% confidence intervals (CI). A multiple logistic regression model will be built including significant co-variables and confounders based on univariable screen (p \< 0.1) or because of clinical significance. A multivariable Cox proportional hazard will be used to assess independent predictors for long-term outcomes with results reported as hazard ratio (HR) with 95% CI. Covariables for these models will be selected based on previously described risk factors and the univariable screen of all available potential confounders. Analyses will be done with SPSS software, version 28.0 (SPSS, Chicago, ILLINOIS, USA).

Conflict of Interest:

The investigators have no conflict of interest to report.

Funding Source:

There are no plans to apply for grants or additional funding. No funding is required for the completion of this study.

Publication Plan:

All research personnel included in this project will be eligible for authorship in any resulting abstracts and publications in accordance with the qualifications outlined by the International Committee of Medical Journal Editors. The order of authors will be determined prior to manuscript development and depend on each individual's contribution to the study.