O-016 - ASSOCIATION BETWEEN BODY MASS INDEX AND MORTALITY FOLLOWING ELECTIVE ENDOVASCULAR AND OPEN REPAIR OF ABDOMINAL AORTIC ANEURYSMS IN THE VASCULAR QUALITY INITIATIVE

TOPIC:
Abdominal Aortic Aneurysms
AUTHORS:
D'Oria M. (Division of Vascular and Endovascular Surgery, Cardiovascular Department, University Hospital of Trieste ~ Trieste ~ Italy) , Neal D. (Division of Vascular Surgery & Endovascular Therapy, University of Florida ~ Gainesville, FL ~ United States of America) , Demartino R. (3Division of Vascular and Endovascular Surgery, Gonda Vascular Center, Mayo Clinic ~ Rochester, MN ~ United States of America) , Mani K. (Division of Vascular Surgery, Department of Surgical Sciences, University of Uppsala ~ Uppsala ~ Sweden) , Budtz-Lilly J. (Department of Cardiovascular Surgery, Division of Vascular Surgery, Aarhus University Hospital ~ Aarhus ~ Denmark) , Calvagna C. (Division of Vascular and Endovascular Surgery, Cardiovascular Department, University Hospital of Trieste ~ Trieste ~ Italy) , Lepidi S. (Division of Vascular and Endovascular Surgery, Cardiovascular Department, University Hospital of Trieste ~ Trieste ~ Italy) , Scali S. (Division of Vascular Surgery & Endovascular Therapy, University of Florida ~ Gainesville, FL ~ United States of America)
Introduction:
The World Health Organization has declared food security and nutrition to be global health priorities, which are some of the most blatantly visible yet neglected public health problems. Food security is complex and may lead to both malnutrition, as well as overnutrition, resulting in obesity. Notably, the implications of malnutrition among vascular surgical patients have received limited attention to date. More specifically, the effect of body mass index (BMI), a commonly used measure of nutritional status, on postoperative outcomes after abdominal aortic aneurysm repair (AAA) remains poorly defined. Therefore, we sought to investigate the association between BMI and mortality following elective endovascular (EVAR) and open (OAR) repair of AAA in a large national quality registry.
Methods:
All elective AAA repairs within the Society for Vascular Surgery Vascular Quality Initiative (VQI; 2010-2020) were reviewed (EVAR: n=53,426; OAR: 9,571). All analyses were conducted separately for patients undergoing EVAR and OAR. The primary end-points were 30-day mortality and 5-year survival. Study cohorts were divided into BMI quintiles (Q1:<20.1; Q2:20.138.2). Spline interpolation was used to verify model performance when determining association with mortality. Mixed-effects Cox regression was used to assess the effect of BMI on survival.
Results:
Among EVAR patients, BMI distribution was: Q1: 2,690 (5%); Q2: 5,366 (10%); Q3: 37,356 (70%); Q4: 5,344 (10%), Q5: 2,670 (5%). Low BMI patients (<20.1) were more likely to be older, female, current smokers, and have COPD but less likely to have multiple cardiovascular risk factors compared to higher BMI categories. Lowest BMI quintile patients had higher 30-day mortality (Q1, 2.2% vs. Q2-5, 0.7-1.6%;p<0.001) and correspondingly worse long-term survival (5-years: Q1, 72±3% vs. Q2-5, 77-88±4%; log-rank p<0.0001) (Figure 1). These survival estimates remained significantly different even after risk-adjustment for multiple confounders. For example, elective EVAR patients with low (<20.1) and high (>38.2) BMI had greatest risk of 30-day mortality (Q1, OR 1.9, 95% CI 1.4-2.7, p=0.0001; Q5, OR 2.1, 95%CI 1.4-3.2, p=0.0002) when compared to all other BMI quintiles. Conversely, increased risk of long-term mortality was most evident among lowest BMI patients (Q1, HR 1.5, 95%CI 1.4-1.70, p<0.0001) while more severe obesity was not associated with worse survival (Q5, HR 1.0, 95%CI 0.9-1.2;p= 0.5). In the OAR cohort, BMI distribution was: Q1: 612 (7%); Q2: 1,022 (10%); Q3: 6,664 (70%); Q4: 806 (9%); Q5: 375 (4%). Analogous to EVAR, similar demographic and comorbidity disparities were present. Crude 30-day mortality rates were higher for both low and high BMI quintile patients (Q1: 8%, Q5: 6% vs. Q2-Q4: 3%-5%;p<0.0001); however, inferior unadjusted long-term survival was only observed among low BMI patients (5-years: Q1: 73±4%: vs. Q2-5: 84-87±4%; log-rank p<0.0001) (Figure 2). In risk-adjusted analysis, low and high BMI OAR patients had higher risk of both 30-day mortality and worse long-term survival (30-day mortality, Q1, OR 1.9, 95%CI 1.3-2.9, p=0.002; Q5, OR 2.5, 95%CI 1.5-4.4, p=0.001) (5-year survival, Q1, HR 1.8, 95%CI 1.4-2.3, p<0.0001; Q5, HR 1.7, 95%1.2-2.3, p=0.001).
Conclusion:
Within VQI, both low (<20.1) and high (>38.2) BMI was associated with greater risk of 30-day mortality after both elective EVAR and OAR. However, the effect of BMI extremes on long-term mortality after these two different repair strategies was different. Specifically, only low BMI (<20.1) was predictive of worse overall survival after EVAR. In contrast, patients with undernutrition (BMI<20.1), as well as more severe obesity (BMI>38.2) were at highest risk for poorer long-term survival after OAR. Based upon this large national quality registry analysis of elective AAA repair, distinct patient phenotypes are present within extreme BMI categories and should inform perioperative risk stratification and clinical decision-making.
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