Multivariate Analysis of 319 Iliac Stents Reveals the Strong Impact of Demographic Factors and Lesion Severity on Stent Patency
Amy Roach, Sebastian Larion, Chad Ammar, Colin Brandt, S. Sadie Ahanchi, Jean Panneton, David Dexter
Eastern Virginia Medical School, Norfolk, VA
BACKGROUND: The aim of our study was to perform a large scale multivariate analysis to identify the demographic, anatomic, or procedural factors that impact primary iliac stent patency.
METHODS: A retrospective chart review of iliac stenting from 2011- 2013 was conducted. Index iliac stenting patients were identified by CPT codes 37220, 37221, 37222, and 37223. Differences in demographic, anatomical, and procedural characteristics were analyzed by univariate analysis between groups based on primary patency. Variables that were considered significant (p<0.05) were brought forward in the cox regression multivariate analysis.
RESULTS: 224 patients underwent primary iliac artery stenting and a total of 319 limbs were analyzed. Average age was 66 years (range 38 to 93), 53% were male, and 57% were Caucasian. Indication for procedure was 64% claudication, 23% rest pain, and 13% ulcer/gangrene. The cohort included all TASC classifications: 50% TASC A, 25% TASC B, 12% TASC C, and 13% TASC D. The treated anatomic location was isolated EIA 27%, isolated CIA 55%, and combined CIA/EIA 18%. Intervention distal to the iliac arteries was performed in 37% of the cohort. There were no procedural related mortalities.
Kaplan Meier analysis at 1 and 3 years revealed a primary patency of 86%/51%, primary assisted patency 98%/89%, and secondary patency of 99%/90%. For those patients with critical limb ischemia preprocedurally, limb salvage was 88% at one year.
Based on Kaplan Meier analysis, primary patency at 1 year for Caucasian patients was 93% versus non Caucasian 79%, P=.001. One year Kaplan Meier primary patency was 76% in patients <60 years of age, 86% in patients 60-70 years of age, and 97% in patients >70 years of age, with a significant difference between all groups, P<.001. Primary patency was significantly different for those with and without EIA occlusion (P<.001), with one year primary patency by Kaplan Meier analysis 71% and 86%, respectively. Primary patency was also significantly different for those with and without aortic occlusion, (P=.008), with one year patency of 84% and 87%, respectively. Reentry device differed significantly between groups (P=.028), with one year patency rates of 79% for reentry device use and 87% for those who did have reentry device.
We evaluated five factors on multivariate analysis and three factors were identified to impact primary patency: Caucasian race (HR, .517; 95% confidence interval [CI], .313-.852; P=.01) and older age at the time of procedure (HR, .945; 95% CI, .920-.971; P<.001) positively impacted patency. EIA occlusion (HR, 2.352; 95% CI, 1.294-4.275; P=.005) negatively impacted primary patency. Aortic occlusion and reentry device were no longer significant in our multivariate model.
In our institution’s experience with a large number of iliac interventions (CIA and EIA), race, age, and EIA occlusion all impacted primary patency. This study emphasizes the underappreciated impact of patient demographics and lesion severity on stenting outcomes.
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