Relationship Between Age and the Comparative Outcomes of Revascularization Procedures in the BEST-CLI Trial: A Spline Model Analysis

BACKGROUND Age remains an important factor in decision making and operative outcomes in patients with CLTI. Prior studies have used arbitrary age categories. Our aim is to identify an evidence-based age cut-off to differentiate patient outcomes between open and endovascular therapy (ET) in the BEST-CLI trial. METHODS The BEST-CLI trial dataset was queried to include all patients who underwent open surgical bypass or ET. Patients' age on the day of the index revascularization was identified as a continuous variable. Restricted cubic splines were generated to examine the moderating effect of age on the outcomes of procedure type in cohort 1 (bypass with SSGSV vs ET) and cohort 2 (bypass with an alternative conduit vs ET). Four separate spline models for each cohort were generated corresponding to our outcomes of interest: major amputation (above-ankle), all-cause mortality, major adverse limb events (MALE defined as above-ankle amputation or major reintervention), and MALE/Death. RESULTS Our study included 1,780 patients, with mean age of 67.2±9.7 (range 27.9-94.1). In cohort 1, the MALE/death spline model showed lower hazard for SSGSV compared to ET across all ages, however, the upper limit of the HR confidence interval approaches 1.0 at age 72. There was no age inflection point identified with regards to mortality. Amputation risk was lower with SSGSV compared to ET up to around the age of 57, beyond which there was no difference between the two treatment modalities. Furthermore, the risk of MALE was consistently lower with SSGSV for patients up to age 83. On the other hand, in cohort 2, age was not found to be an effect modifier in revascularization outcomes or survival among patients undergoing bypass with an alternative conduit compared to ET. CONCLUSIONS In this study, we confirmed that bypass with SSGSV was associated with superior MALE-free survival compared to ET up to the age of 72, beyond which there was no significant difference in outcomes between the two strategies. MALE was significantly higher for ET for patients up to age 83. Patients' age was not found to favor one revascularization method over the other if the bypass was performed using an alternative conduit. Further studies are needed to compare the effectiveness of revascularization strategies among older patients with CLTI.