Study Evaluates Outcomes of Surgery and EVAR in Obese Versus Nonobese AAA Patients
December 12, 2018—The Society for Vascular Surgery (SVS) announced that new research suggests a significant increase in morbidities in obese patients treated for abdominal aortic aneurysm (AAA) after open aneurysm repair (OAR) but not after endovascular aneurysm repair (EVAR). The study was published by Satinderjit Locham, MD, et al in the Journal of Vascular Surgery (JVS; 2018;68:1696-1705).
The investigators from Johns Hopkins University in Baltimore, Maryland, led by Mahmoud Malas, MD, found that obese patients compared with nonobese patients were more likely to have longer procedures, lose more blood during the procedure, and have postoperative problems such as renal failure or wound infections.
In the SVS announcement, Dr. Malas commented, “Wound infection is a common complication seen among obese patients undergoing all surgical procedures. Even after adjusting for comorbid conditions, the obese had 75% higher odds of wound infection following open repair, with the highest rates observed in the more severely obese patients. In this study, open repair showed an increased risk of all in-hospital complications compared with endovascular therapy for AAA, corroborating the known superiority of endovascular repair over open repair seen in the literature.”
According to SVS, the investigators performed a retrospective analysis of prospectively collected data by the Vascular Quality Initiative from 2003 to 2017 with the aim of comparing in-hospital outcomes in obese (body mass index [BMI] ≥ 30 kg/m2) versus nonobese patients undergoing AAA repair.
Dr. Malas noted, “In this large national sample of an elective AAA cohort, obese patients had similar in-hospital mortality compared with nonobese patients in both open and endovascular repairs. The results remained unchanged even after looking at different subclasses of obesity, including those with BMI > 40 kg/m2.”
As summarized by SVS, the study evaluated 33,082 procedures including OAR (obese, n = 1,754; nonobese, n = 4,604) and EVAR (obese, n = 8,385; nonobese, n = 18,338). The majority of both obese and nonobese patients were men (OAR, 76% vs 73%; EVAR, 82% vs 81%). Obese patients compared with nonobese patients were younger (67.6 vs 70.3 years) and more likely to have significant comorbid conditions (ie, diabetes, hypertension, coronary artery disease, and congestive heart disease).
The investigators implemented univariable (Student t-test and χ2 test) and multivariable (logistic regression) analyses to compare in-hospital mortality and any major complications (eg, wound infection, renal failure, and cardiopulmonary failure) in obese versus nonobese patients.
In the procedures, obese versus nonobese patients experienced higher blood loss (OAR, 2,030 vs 1,617 ml; EVAR, 228 vs 207 ml) and longer operations (open, 259 vs 239 mins; EVAR, 138 vs 134 mins). There was no difference in mortality between the groups for either repair method (OAR, 3% vs 3%; EVAR, 0.5% vs 0.6%).
The investigators reported in JVS, "On multivariable analysis, obese patients undergoing OAR had 33% higher odds of renal failure (adjusted odds ratio [OR], 1.33; 95% confidence interval [CI], 1.09–1.63; P = .006) and 75% higher odds of wound infections (adjusted OR, 1.75; 95% CI, 1.11–2.76; P = .02) compared with nonobese patients. However, in patients undergoing EVAR, no association was seen between obesity and any major complications. A significant interaction was found between obesity and surgical approach in the event of renal failure, in which obese patients undergoing OAR had significantly higher odds of renal failure compared with those in the EVAR group (OR, 1.36; 95% CI, 1.05–1.75; P = .02)."
As noted in the SVS press release, previous studies defining early outcomes after AAA in the obese have yielded conflicting results. A recent meta-analysis suggested the superiority of EVAR over OAR, but only four studies with relatively small numbers were included. Single-center studies have either corroborated this conclusion or failed to demonstrate a difference.
"Further long-term prospective studies are needed to verify the effects of obesity after AAA repair and the implications of these findings in clinical decision-making," advised the investigators in JVS.