Outcomes after elective abdominal aortic aneurysm repair in obese versus nonobese patients

Obesity and the obesity paradox in abdominal aortic aneurysm

Obesity, characterized by its complexity and heterogeneity, has emerged as a significant public health concern. Its association with increased incidence and mortality of cardiovascular diseases stems not only from its complications and comorbidities but also from the endocrine effects of adipose tissue. Abdominal aortic aneurysm (AAA), a chronic inflammatory condition, has been closely linked to obesity. Intriguingly, mild obesity appears to confer a protective effect against AAA mortality, whereas severe obesity and being underweight do not, giving rise to the concept of the "obesity paradox". This review aims to provide an overview of obesity and its paradoxical relationship with AAA, elucidate its underlying mechanisms, and discuss the importance of preoperative weight loss in severely obese patients with AAA.

Open Conversion with Explantation of Stent Grafts After Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm

BACKGROUND

Although endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) is widely used worldwide, the fact that it is associated with increased rates of reintervention has been considered a problem. This study aimed to analyze the outcomes of primary open AAA repair and open conversion with explantation of stent grafts after EVAR.

METHODS

In this retrospective study, we enrolled 1,120 patients (open repair, n = 664; EVAR, n = 456) who underwent AAA repair at Kobe University from 1999 to 2019. Of the 664 patients who underwent open repair, 121 (patients who underwent primary open repair (POR) as a concomitant procedure and patients with ruptured AAA) were excluded from the study. The outcomes of POR were compared with those of open conversion with explantation of stent grafts.

RESULTS

Of the 543 patients who underwent open repair, 513 underwent POR and 30 underwent open conversion with explantation of stent grafts. The operation time for POR was significantly less than that for open conversion with explantation. During surgery, patients who underwent open conversion with explantation required significantly more transfusions of red cell concentrate, fresh frozen plasma, and platelet concentrate than those who underwent POR. Overall, 30 patients who underwent open conversion with explantation required a total of 48 reinterventions before surgery. Hospital mortality rates were 0.7% and 0% in the POR and open conversion with explantation groups, respectively (P = 0.62). Although overall survival at 5 years in the POR group was significantly better than that in the open conversion with explantation group (89.3 ± 1.7% vs. 79.5 ± 9.6%; P = 0.01), there were no significant differences between the 2 groups regarding the freedom from aortic event (hospital death, reintervention, and aortic death). According to the multivariate analysis, open conversion with explantation was not an independent risk factor for late death. There were 20 patients who were hesitant to undergo OCE, although we recommended OCE. In a subgroup analysis, the overall mean cost borne by patients who underwent EVAR was approximately 2.3 times higher compared with that borne by patients who underwent POR.

CONCLUSIONS

Although demanding, both early and long-term outcomes of OCE have been favorable in our present study. OCE is highly recommended in patients with persistent sac enlargement after EVAR.

Impact of Serum Albumin Levels and Body Mass Index on Outcomes of Open Abdominal Aortic Aneurysm Repair in Korean Population

BACKGROUND

Although obese patients seem to be susceptible to chronic diseases, obesity paradox has been observed in the field of vascular surgery, in which many previous studies have reported that overweight patients have good postoperative outcomes and underweight patients have poor postoperative outcomes. The purpose of our study is to evaluate the impact of body mass index (BMI) and serum albumin levels, which are evaluated as indicators of nutritional status, on outcomes of open abdominal aortic aneurysm (AAA) repair.

METHODS

We reviewed the vascular surgery database of a single tertiary referral center for all patients who underwent open AAA repair due to degenerative etiology from 1996 to 2021. To analyze the effect of BMI, patients were classified into 4 groups according to the Asian-Pacific classification of BMI: underweight (UW) (<18.5 kg/m2), normal weight (NW) (18.5-22.9 kg/m2), overweight (OW) (23-24.9 kg/m2), and obese (OB) (≥25 kg/m2). The χ2, Fisher's exact, and Kruskal-Wallis tests were used to compare demographics, comorbidities, radiologic findings, surgical details, and 1-year mortality rates between the 4 groups. We also compared the preoperative serum albumin levels of each group to assess nutritional status indirectly. Cox's proportional hazards model was performed to determine factors associated with mortality. A Kaplan-Meier survival analysis was performed, and the differences were analyzed by a log-rank test. We did not perform an analysis for 30-day mortality because cases of 30-day mortality in UW patients were rare due to the unbalanced distribution of the number of patients in the 4 groups.

RESULTS

Among a total of 678 patients, 22 were classified as UW (3.2%), 200 as NW (29.5%), 183 as OW (27.1%), and 273 as OB (40.1%). The median age was 70 (64-75) years and 577 of 678 (85.1%) patients were male gender. Higher serum albumin level was associated with decreased 1-year mortality (hazard ratio [HR], 0.3; 95% confidence interval [CI], 0.15-0.63; P = 0.001). UW patients had a higher 1-year mortality rate than NW patients (HR, 3.67; 95% CI, 1.02-13.18; P = 0.046). OB patients had a lower overall mortality rate than NW patients (HR, 0.73; 95% CI, 0.53-1; P = 0.05).

CONCLUSIONS

Low BMI (<18.5 kg/m2) and low serum albumin level were associated with poor 1-year survival after elective open AAA repair. These patients also need more careful preoperative intervention, like weight gain or nutritional support, for better outcomes. The obesity paradox existed in our study; high BMI (≥25 kg/m2) was associated with better overall survival after elective open AAA repair.

Body Mass Index Impacts Indication But Not Outcomes of Thoracic Endovascular Aortic Repair

BACKGROUND

There are limited studies looking at thoracic endovascular aortic repair (TEVAR) outcomes in obese and overweight patients. Our objective was to determine the rate of complications, reintervention, and short-term mortality in normal weight, overweight, and obese patients undergoing TEVAR.

METHODS

Patients undergoing TEVAR at a large tertiary hospital from October 2007 to January 2020 were analyzed. Patients were stratified into 3 cohorts based on body mass index (BMI): normal (18.5-25 kg/m2), overweight (25-30 kg/m2), and obese (>30 kg/m2). Primary outcomes were 30-day and 1-year survival. Intraoperative, in-hospital, and postdischarge complications were assessed as secondary outcomes using the Clavian-Dindo classification system. In addition, reinterventions associated with the index TEVAR procedure as a secondary outcome.

RESULTS

Among 204 patients fitting the study criteria, we identified 65 with normal BMI, 78 overweight, and 61 obese patients. Obese patients were younger than the overweight and normal BMI patients (mean age 62.2 vs. 66.7 vs. 70.7, respectively, P = 0.003). In terms of TEVAR indication, the obese cohort had the highest percentage of patients with type B aortic dissection (36.4%), while the normal BMI cohort had the higher proportion of patients undergoing TEVAR for isolated thoracic aortic aneurysm (63.9%). Intraoperative complications did not significantly differ between cohorts. Postoperatively, in-hospital complications, postdischarge complications and 30-day return to the operative room did not differ significantly between study cohorts. Odds of reintervention did not differ significantly between cohorts, both on univariate and multivariate analysis. Log-rank test of Kaplan Meier analysis revealed no difference in reintervention-free survival (P = 0.22). Thirty-day mortality and 1-year overall survival were similar across cohorts. Both univariate and multivariate logarithmic regression revealed no difference in likelihood of 30-day mortality between the obese and normal cohort.

CONCLUSIONS

There were no measurable differences in complications, reinterventions, or mortality, suggesting that vascular surgeons can perform TEVAR across a spectrum of BMI without compromising outcomes.

Improving hospital quality risk-adjustment models using interactions identified by hierarchical group lasso regularisation

BACKGROUND

Risk-adjustment (RA) models are used to account for severity of illness in comparing patient outcomes across hospitals. Researchers specify covariates as main effects, but they often ignore interactions or use stratification to account for effect modification, despite limitations due to rare events and sparse data. Three Agency for Healthcare Research and Quality (AHRQ) hospital-level Quality Indicators currently use stratified models, but their variable performance and limited interpretability motivated the design of better models.

METHODS

We analysed patient discharge de-identified data from 14 State Inpatient Databases, AHRQ Healthcare Cost and Utilization Project, California Department of Health Care Access and Information, and New York State Department of Health. We used hierarchical group lasso regularisation (HGLR) to identify first-order interactions in several AHRQ inpatient quality indicators (IQI) - IQI 09 (Pancreatic Resection Mortality Rate), IQI 11 (Abdominal Aortic Aneurysm Repair Mortality Rate), and Patient Safety Indicator 14 (Postoperative Wound Dehiscence Rate). These models were compared with stratum-specific and composite main effects models with covariates selected by least absolute shrinkage and selection operator (LASSO).

RESULTS

HGLR identified clinically meaningful interactions for all models. Synergistic IQI 11 interactions, such as between hypertension and respiratory failure, suggest patients who merit special attention in perioperative care. Antagonistic IQI 11 interactions, such as between shock and chronic comorbidities, illustrate that naïve main effects models overestimate risk in key subpopulations. Interactions for PSI 14 suggest key subpopulations for whom the risk of wound dehiscence is similar between open and laparoscopic approaches, whereas laparoscopic approach is safer for other groups. Model performance was similar or superior for composite models with HGLR-selected features, compared to those with LASSO-selected features.

CONCLUSIONS

In this application to high-profile, high-stakes risk-adjustment models, HGLR selected interactions that maintained or improved model performance in populations with heterogeneous risk, while identifying clinically important interactions. The HGLR package is scalable to handle a large number of covariates and their interactions and is customisable to use multiple CPU cores to reduce analysis time. The HGLR method will allow scholars to avoid creating stratified models on sparse data, improve model calibration, and reduce bias. Future work involves testing using other combinations of risk factors, such as vital signs and laboratory values. Our study focuses on a real-world problem of considerable importance to hospitals and policy-makers who must use RA models for statutorily mandated public reporting and payment programmes.

Raised BMI is associated with fewer Type I endoleaks in patients treated with the Gore Excluder device: data from the Global Registry for Endovascular Aortic Treatment (GREAT)

BACKGROUND

Obesity is increasing in prevalence globally and within the cohort of vascular surgical patients, leading to poorer outcomes. There are few data on endoleak as a complication of AAA surgery in obese patients. The aim of this study was to use large scale registry data from the Global Registry for Endovascular Aortic Treatment (GREAT) to interrogate any relationship between obesity and endoleak following endovascular aneurysm repair (EVAR) using a Gore Excluder device (W. L. Gore & Associates, Newark, DE, USA), in order to guide treatment recommendations in the future.

METHODS

A retrospective review of the GREAT Registry was carried out and patients who were recorded as having a postoperative endoleak requiring intervention were included. Patient demographics including Body Mass Index (BMI), aneurysm parameters and on- or off-instructions for use (IFU) were recorded. Ruptured AAA were excluded.

RESULTS

Data were obtained for 3326 patients with an operation date between August 25, 2010 and September 22, 2019. Obese patients were significantly less likely to have a Type 1 endoleak (Fisher's Exact P value=0.006), and the association was maintained in a multiple logistic regression model which controlled for age, gender, neck angulation and off IFU device use (OR=0.33, P=0.01).

CONCLUSIONS

Among AAA patients treated with a Gore Excluder device (W. L. Gore & Associates), a higher BMI category was associated with a lower risk of Type 1 endoleak requiring reintervention. Further work needs to be carried out to assess our findings in other patient cohorts.

Japanese single-center experience of abdominal aortic aneurysm repair over 20 years: should open or endovascular aneurysm repair be performed first?

PURPOSE

The present study analyzed the outcomes of our experience with abdominal aortic aneurysm (AAA) repair over 20 years using endovascular aortic repair (EVAR) with commercially available devices or open aortic repair (OAR) and reviewed our surgical strategy for AAA.

METHODS

From 1999 to 2019, 1077 patients (659 OAR, 418 EVAR) underwent AAA repair. The OAR and EVAR groups were compared retrospectively, and a propensity matching analysis was performed.

RESULTS

EVAR was first introduced in 2008. Our strategy was changed to an EVAR-first strategy in 2010. Beginning in 2018, this EVAR-first strategy was changed to an OAR-first strategy. After propensity matching, the overall survival in the OAR group was significantly better than that in the EVAR group at 10 years (p = 0.006). Two late deaths due to AAA rupture were identified in the EVAR group, although there were no significant differences between the OAR and EVAR groups with regard to the freedom from AAA-related death at 10 years. The rate of freedom from aortic events at 10 years was significantly higher in the OAR group than in the EVAR group (p < 0.0001).

CONCLUSION

The rates of freedom from AAA-related death in both the OAR and EVAR groups were favorable, and the rate of freedom from aortic events was significantly lower in the EVAR group than in the OAR group. Close long-term follow-up after EVAR is mandatory.

Obesity is Not Associated with Adverse Perioperative or Poorer Clinical Outcomes following Thoracic and Fenestrated-Branched Endovascular Aortic Repair

BACKGROUND

Obesity is a risk factor for higher morbidity and mortality following open aortic repair but currently there is limited literature on its impact on clinical and procedural outcomes following thoracic endovascular aortic repair (TEVAR) and branched-fenestrated endovascular aortic repair (B-FEVAR).

METHODS

We conducted a retrospective case-control analysis of a prospectively collected nonrandomized database to evaluate the effects of obesity on procedural and clinical outcomes after B-FEVAR/TEVAR in treatment of pararenal/thoracoabdominal aortic aneurysm and dissection at the University hospital of Nantes (France) between January 2016 and December 2021. Patients were divided in 2 groups according to their body mass index (BMI) and the rate of technical success, complications (renal, pulmonary, cardiac, and neurological events), 30-day and long-term survival, freedom from target vessel instability and reintervention were compared.

RESULTS

195 patients were included (mean age 69.6 DS±11.2; n = 135, 69.2% men; mean BMI: 26.6 kg/m2 range 19-41) totalling n = 72 (36.8%) TEVAR, n = 107 (55.4%) FEVAR and n = 14 (7.3%) BEVAR. Patients were divided in 2 groups [obese: BMI≥30 kg/m2n = 52 (26.7%); and nonobese, BMI<30 kg/m2, n = 143 (73.3%) that statistically differed only in terms of coronary artery disease (obese 42.3% vs. 26.6% nonobese, P = 0.035) and diabetes (obese 25% vs. 12.6% nonobese, P = 0.03). No statistical differences were noted in primary technical (94.2% vs. 94.4%, P = 1.00) and clinical (92.3% vs. 95.1%, P = 0.49) success. Overall morbidity (30.8% vs. 21.1%, P = 0.16), visceral vessels instability (1.9% vs. 1.4% P = 1.00), reintervention rate within 30 days (9.6% vs. 5.6% P = 0.33), 90 days (7.7% vs. 9.8%, P = 0.78) and during follow-up (9.8% vs. 20%, P = 0.14) were comparable. No statistical difference were noted in 30-day mortality (3.8% vs. 4.9%, P = 1.00) and the 2-year follow-up survival (86.8% vs. 78.4%, P = 0.180) between the 2 groups.

CONCLUSIONS

In this series, obesity was not associated to worst clinical outcomes or higher mortality rate following TEVAR/B-FEVAR. However, considering our small patient sample, a conclusive analysis on obesity as risk factors for adverse events after endovascular treatment is not possible. A larger sample from the collaboration of multiple centers will be required to obtain definitive conclusions.

The Association Between Body Mass Index and Death Following Elective Endovascular and Open Repair of Abdominal Aortic Aneurysms in the Vascular Quality Initiative

OBJECTIVE

The effect of body mass index (BMI) on post-operative outcomes after abdominal aortic aneurysm (AAA) repair remains poorly defined. The association between BMI and death following elective endovascular aneurysm repair (EVAR) and open aneurysm repair (OAR) of AAA in a large national quality registry is investigated.

METHODS

All elective AAA repairs within the Society for Vascular Surgery Vascular Quality Initiative (VQI; 2010 to September 2021) were reviewed (EVAR, n = 53 426; OAR, n = 9 479). All analyses were conducted separately for EVAR and OAR patients. The primary end points were 30 day mortality and five year survival rates. Study cohorts were divided into World Health Organisation BMI categories (C1 < 18.5, C2 18.5 ≤ BMI < 25, C3 25 ≤ BMI < 30, C4, 30 ≤ BMI < 35, C5 35 ≤ BMI < 40, C6 ≥ 40). BMI was examined as both a categorical and continuous variable. Logistic and Cox proportional hazards regression were used for risk adjustment.

RESULTS

Among EVAR patients, BMI distribution was C1, 1 216 (2%); C2, 14 687 (28%); C3, 20 516 (38%); C4, 11 352 (21%); C5, 3 947 (7%); C6, 1 708 (3%). Class 1, 2, and 6 BMI patients experienced an increased 30 day mortality rate (C1 2.6%; C2 1.3%; C6 1.4% vs. C3 - 5 0.7%; p < .001) and C1 and C2 had correspondingly inferior long term survival (five years: C1 69 ± 3%; C2 79 ± 1% vs. C3 - 6 86 - 88 ± 2%; log rank p < .001). These survival disparities persisted after risk adjustment for multiple confounders. In the OAR cohort, BMI distribution was C1, 280 (3%); C2, 2 862 (30%); C3, 3 587 (38%); C4, 1 940 (21%); C5, 581 (6%); C6, 229 (2%). Crude 30 day mortality rates were increased for both the lowest and highest BMI patients (C1 12%, C6 7% vs. C2 - 5 3 - 4%; p < .001); these differences also persisted in long term survival (five years: C1 71 ± 6%, C6 82 ± 6% vs. C2 - 6 85 - 88 ± 3%; log rank p < .001). In risk adjusted analysis, both low and high BMI OAR patients had an increased 30 day and long term mortality rate.

CONCLUSION

Within the VQI, both the extreme low (< 18.5) and high (≥ 40) BMI groups experienced an increased 30 day mortality rate after both elective EVAR and OAR. By comparison, while the lowest BMI cohort was significantly associated with decreased long term survival after both procedures, the highest BMI group only experienced reduced long term survival after OAR. Based upon this large real world registry analysis of elective AAA repairs, differential metabolic signatures exist within extreme BMI categories, which may inform peri-operative risk stratification and clinical decision making.

The impact of obesity on perioperative and postoperative outcomes after elective endovascular abdominal aortic aneurysm repair

BACKGROUND

Obesity is a common and growing health problem in vascular surgery patients, as it is in all patient groups. Evidence regarding body mass index (BMI) on endovascular aneurysm repair (EVAR) outcomes is not clear in the literature. We aimed to determine the impact of obesity on perioperative and midterm outcomes of elective EVAR between obese and non-obese patients.

METHODS

Under a retrospective study design, a total of 120 patients (109 males, 11 females, mean age: 74.45 ± 8.59 (53-92 years)) undergoing elective EVAR between June 2012 and May 2020 were reviewed. Patients were stratified into two groups: obese (defined as a body mass index (BMI) ≥ 30 kg/m²) and non-obese (mean BMI < 30 kg/m² (32.25 ± 1.07 kg/m² vs 25.85 ± 2.69 kg/m²)).

RESULTS

Of the 120 patients included in the study, 81 (67.5%) were defined as "nonobese," while 39 (32.5%) were obese. The mean BMI of the study group was 27.93 ± 3.78 kg/m². In obese patients, the procedure time, fluoroscopy time, and dose area product (DAP) values were longer than those of non-obese patients: 89.74 ± 20.54 vs 79.69 ± 28.77 min (p = 0.035), 33.23 ± 10.14 vs 38.17 ± 8.61 min (p = 0.01) and 133.69 ± 58.17 vs 232.56 ± 51.87 Gy.cm² (p < 0.001). Although there was no difference in sac shrinkage at 12-month follow-up, there was a significant decrease at 6-month follow-up in both groups (p = 0.017). Endoleak occurred in 17.9% (n = 7) of the obese group versus 11.1% (n = 9) of the non-obese group (p = 0.302). Iliac branch occlusion developed in four patients, 3 (3.7%) in the non-obese group and 1 (2.6%) in the obese group (p = 0.608). The all-cause mortality rate was slightly higher in the obese group; however, it did not differ between the groups (p = 0.463).

CONCLUSION

In addition to the longer procedure times, fluoroscopy times, and DAP values in obese patients, regardless of obesity, significant sac shrinkage in the first 6 months of follow-up was observed in both groups. No difference was documented with regards to mortality or morbidity following EVAR.

Association Between Obesity and Outcomes Following Endovascular Aneurysm Repair

BACKGROUND

Obesity is prevalent in patients with abdominal aortic aneurysms (AAA). There is an association between increasing body mass index (BMI) and increased overall cardiovascular mortality and morbidity. This study aims to assess the difference in mortality and complication rates between normal weight (NW), overweight (OW), and obese patients undergoing endovascular aneurysm repair (EVAR) for infrarenal AAA.

METHODS

This is a retrospective analysis of consecutive patients undergoing EVAR for AAA between January 1998 and December 2019. Weight classes were defined as: BMI<18.5 kg/m², underweight; BMI 18.5-24.9 kg/m², NW; BMI 25.0-29.9 kg/m², OW; BMI 30.0-39.9 kg/m², obese; BMI>39.9 kg/m² morbidly obese. Primary outcomes were long-term all-cause mortality and freedom from reintervention. Secondary outcome was aneurysm sac regression (defined as a reduction in sac diameter of 5 mm or more). Kaplan-Meier survival estimates and mixed model analysis of variance were used.

RESULTS

The study included 515 patients (83% males, mean age 77 ± 8 years) with a mean follow-up of 3.8 ± 2.8 years. In terms of weight class, 2.1% (n = 11) were underweight, 32.4% (167) were NW, 41.6% (n = 214) were OW, 21.2% (n = 109) were obese, and 2.7% (n = 14) were morbidly obese. Obese patients were younger (mean difference -5.0 years) but had a higher prevalence of diabetes mellitus (33.3% vs. 10.6% for NW) and dyslipidemia (82.4% vs. 60.9% for NW). Obese patients had similar freedom from all-cause mortality (88%) compared to OW (78%) and NW (81%) patients. The same findings were evident for freedom from reintervention where obese (79%) was similar to OW (76%) and NW (79%). At a mean follow-up of 5.1 ± 0.4 years, sac regression was observed similarly across weight classes at 49.6%, 50.6%, and 51.8% for NW, OW, and obese, respectively (P = 0.501). There was a significant difference in mean AAA diameter pre- and post-EVAR [F(2,318) = 24.37, P < 0.001] across weight classes. NW [mean reduction 4.8 mm (2.0-7.6 mm, P < 0.001)], OW [mean reduction 3.9 mm (1.5-6.3 mm, P < 0.001)], and obese [mean reduction 5.7 mm (2.3-9.1 mm, P < 0.001)] achieved similar reductions.

CONCLUSIONS

Obesity was not associated with increased mortality or reintervention in patients undergoing EVAR. Obese patients achieved similar rates of sac regression on imaging follow-up.

Effect of Body Mass Index on Early Outcomes of Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

This study compares the presentation, management, and outcomes of patients undergoing endovascular abdominal aortic aneurysm repair (EVAR), based on their weight status as defined by their body mass index (BMI).

METHODS

Patients with primary EVAR for ruptured and intact abdominal aortic aneurysm (AAA) were identified in the National Surgical Quality Improvement Program database (2016-2019). Patients were categorized by weight status (underweight: BMI < 18.5 kg/m², normal weight: 18.5-24.9 kg/m², overweight: 25-29.9 kg/m², Obese I: 30-34.9 kg/m², Obese II: 35-39.9 kg/m², Obese III: > 40 kg/m²). Preoperative characteristics and 30-day outcomes were compared.

RESULTS

Of 3,941 patients, 4.8% were underweight, 24.1% normal weight, 37.6% overweight, and 22.5% with Obese I, 7.8% Obese II, and 3.3% Obese III status. Underweight patients presented with larger (6.0 [5.4-7.2] cm) and more frequently ruptured (25.0%) aneurysms than normal weight patients (5.5 [5.1-6.2] cm and 4.3%, P < 0.001 for both). Pooled 30-day mortality was worse for underweight (8.5%) compared to all other weight status (1.1-3.0%, P < 0.001), but risk-adjusted analysis demonstrated that aneurysm rupture (odds ratio [OR] 15.9, 95% confidence interval [CI] 8.98-28.0) and not underweight status (OR 1.75, 95% CI 0.73-4.18) accounted for increased mortality in this population. Obese III status was associated with prolonged operative time and respiratory complications after ruptured AAA, but not 30-day mortality (OR 0.82, 95% CI 0.25-2.62).

CONCLUSIONS

Patients at either extreme of the BMI range had the worst outcomes after EVAR. Underweight patients represented only 4.8% of all EVARs, but 21% of mortalities, largely attributed to higher incidence of ruptured AAA at presentation. Severe obesity, on the other hand, was associated with prolonged operative time and respiratory complications after EVAR for ruptured AAA. BMI, as an independent factor, was however not predictive of mortality for EVAR.

The Implications of Surgeon Case Volume and Hospital Volume on Outcomes of Aortobifemoral Bypasses in Obese Patients

BACKGROUND

Aortobifemoral (ABF) bypass is the gold standard for treating symptomatic aortoiliac occlusive disease. In the era of heightened interest in the length of stay (LOS) for surgical patients, this study aims to investigate the association of obesity with postoperative outcomes at the patient, hospital, and at surgeon levels.

METHODS

This study utilized the Society of Vascular Surgery (SVS) Vascular Quality Initiative (VQI) suprainguinal bypass database from 2003-2021. The selected study cohort was divided into obese patients (BMI ≥30) (Group I) and non-obese patients (BMI <30) (Group II). Primary outcomes of the study included mortality, operative time, and postoperative LOS. Univariate and multivariate logistic regression analyses were performed to study the outcomes of ABF bypass in Group I. Operative time, and postoperative LOS were transformed into binary values by median split for regression analysis. A p-value of ≤ 0.05 was deemed statistically significant in all the analyses of this study.

RESULTS

The study cohort consisted of 5,392 patients. In this population, 1,093 were obese (Group I), and 4,299 were non-obese (Group II). Group I was found to have more females with higher rates of comorbid conditions, including hypertension, diabetes mellitus, and congestive heart failure. Patients in Group I had increased odds of prolonged operative time (≥ 250 mins) and an increased LOS (≥6 days). Patients in this Group also had a higher chance of intraoperative blood loss, prolonged intubation, and required vasopressors postoperatively. There was also an increased odds of postoperative decline in renal function in the obese population. Patients with prior history of CAD, hypertension, diabetes mellitus, and urgent or emergent procedures were found to be risk factors for LOS>6 days in obese patients. An increase in the surgeons' case volume was associated with lesser odds of operative time ≥ 250 mins; however, no significant impact was found on postoperative LOS. Hospitals where ≥ 25% ABF bypasses were performed on obese patients were also more likely to have LOS <6 days after ABF operations, compared to hospitals where <25% of ABF bypasses were performed on obese patients. Patients undergoing ABF for CLTI or acute limb ischemia had longer LOS and increased operative time.

CONCLUSION

ABF bypass in obese patients is associated with prolonged operative times and longer LOS than in non-obese patients. Obese patients operated by surgeons with more cases of ABF bypasses have shorter operative times. An increasing hospital's obese patient proportion was related to decreased LOS. These findings support the known volume-outcome relationship that with a higher surgeon case volume and increased proportion of obese patients in a hospital, there is an improvement in outcomes of obese patients undergoing ABF bypass.

Open Abdominal Aortic Aneurysm Surgery and Renal Dysfunction; Association of Demographic and Clinical Variables with Proximal Clamp Location

BACKGROUND

While cross-clamp site is a known risk factor for postoperative acute and chronic renal dysfunction following open abdominal aortic aneurysm surgery (AAA), the additive impact of patient demographic and clinical factors is lacking. In this study, we investigated the impact of body mass index (BMI), surgical duration and aneurysm diameter on the association between proximal cross-clamp location and postoperative renal dysfunction.

METHODS

In this study, we conducted a retrospective analysis of 4,197 patients undergoing open AAA surgery between 2011 and 2018 using data housed in the American College of Surgeons National Safety Quality Improvement Program (ACS-NSQIP) database. The primary outcome was renal dysfunction, which was defined as patients requiring dialysis within 30 days or patients with ≥2 mg/dL rise in creatinine from baseline. We assessed the incidence of renal dysfunction with regard to clamp location and subsequently used multivariable logistic regression to assess clinical and demographic factors associated with renal dysfunction. We used a regression model to plot the association of BMI, surgical duration, and aneurysm diameter with an adjusted probability of postoperative acute and chronic renal dysfunction for individual cross-clamp locations.

RESULTS

Of the 4,197 patients analyzed, 405 patients (9.6%) developed renal dysfunction within 30 days with 287 patients requiring dialysis. Patients with supraceliac clamp location had the highest incidence of renal dysfunction (20.4%). Our data showed a significant association of renal dysfunction with higher BMI patients [OR 1.04 (1.02, 1.07), P = 0.001], longer operative times [OR1.01 (1.01, 1.02), P < 0.001], clamp location between the superior mesenteric artery (SMA) and renal artery [OR 1.80 (1.17, 2.78), P = 0.007] and supraceliac clamp location [OR 2.47 (1.62, 3.76), P < 0.001].

CONCLUSIONS

The incidence of renal dysfunction increases with suprarenal clamps. Patients with higher BMI, longer operative times, and increasing aneurysm diameter, and a suprarenal clamp have a significantly increased risk of renal dysfunction compared to those who also had a suprarenal clamp but lower BMI, shorter operative times and smaller aneurysm diameter.

New Measures, Old Conclusions: Obesity Does Not Worsen Outcomes after Elective Abdominal Aortic Aneurysm Repair

Background  The “obesity paradox,” whereby the body mass index (BMI) mortality curve is “U-shaped,” is a well-studied phenomenon in vascular surgery. However, there has been an overreliance on BMI as the measure of obesity, which has shown to poorly correlate with clinical outcomes. Robust measures such as waist-hip ratio (WHR) have been suggested as a more accurate marker reflecting central obesity.

Objectives  The objectives of this study were to evaluate the correlation between BMI and WHR on postoperative morbidity and mortality after elective abdominal aortic aneurysm (AAA) repair.

Methods  Data were collected from the Leeds Vascular Institute between January 2006 and December 2016. The primary outcome was mortality and secondary outcomes included length of stay (LOS) and all-cause readmission. Binary logistic regression, linear regression, and correlation analysis were used to identify associations between BMI and WHR in relation to outcome measures.

Results  After exclusions, 432 elective AAA repairs (281 open surgical repair [OSR] and 151 endovascular aneurysm repairs [EVARs]) were identified to be eligible for the study. The combined 30-day and 4-year mortality was 1.2 and 20.1%, respectively. The 30-day readmission rate was 3.9% and the average LOS was 7.33 (standard deviation 18.5) days. BMI data was recorded for 275 patients (63.7%) and WHR for 355 patients (82.2%). Logistic regression analysis highlighted no association between BMI and WHR with mortality, readmission, or LOS following OSR or EVAR.

Conclusion  The results of this study suggest patients should not be denied treatment for AAA based on obesity alone.

Short-term Mortality and Postoperative Complications of Abdominal Aortic Aneurysm Repair in Obese versus Non-obese Patients

Background

Obesity is a risk factor not only for abdominal aortic aneurysm (AAA) but also for complications after vascular surgery. This study was to determine the effect of obesity on short-term mortality and post-intervention complications after AAA repair.

Methods

A systematic review and meta-analysis were performed. A systematic search was performed in PubMed; the articles describing the differences in post-intervention complications after open or endovascular repair of an AAA between obese and non-obese patients were selected. The primary outcome was short-term mortality defined as in-hospital mortality or mortality within 30 days after AAA repair. The secondary outcomes were cardiac complications, pulmonary failure, renal failure, and wound infections. The meta-analysis was performed using OpenMeta.

Results

Four articles were included in the meta-analysis; these articles included 35,989 patients of which 10,917 (30.3%) were obese. The meta-analysis showed no significant differences for short-term mortality (odds ratio [OR], 0.85; 95% confidence interval [CI], 0.69-1.04). Also, no significant difference was found in pulmonary failure (OR, 1.09; 95% CI, 0.85-1.42). However, obese patients were less likely to suffer from cardiac complications (OR, 0.73; 95% CI, 0.55-0.96). Nevertheless, there was a significantly higher risk of renal failure (OR, 1.16; 95% CI, 1.05-1.30) and wound infections (OR, 1.92; 95% CI, 1.55-2.38) in obese patients.

Conclusion

Obesity is not a risk factor for short-term mortality after AAA repair compared to non-obesity. Moreover, obese patients suffer less from cardiac complications than non-obese patients.

A systematic review and meta-analysis evaluating the impact of obesity on outcomes of abdominal aortic aneurysm treatment

OBJECTIVE

We sought to evaluate the impact of obesity on perioperative mortality and complication rates in patients undergoing endovascular aortic repair (EVAR) and open surgical repair (OSR) for abdominal aortic aneurysms (AAA).

METHODS

A systematic review of all studies reporting AAA treatment perioperative (30 day) outcomes in obese patients (body mass index ≥30 kg/m²). The primary outcome was 30 day mortality. Secondary outcomes included: cardiac complications, respiratory complications, wound complication, renal complications, and neurological complications at 30 days. These outcomes were pooled for meta-analysis. Analysis first compared obese versus nonobese patients undergoing EVAR and OSR then compared EVAR to OSR in obese patients.

RESULTS

We identified 7 observational studies with 14,971 patients (11,743 EVAR, 3228 OSR). Obese patients undergoing EVAR had lower 30 day mortality (1.5%) compared to nonobese patients (2.2%) (OR 0.69; 95% CI 0.50-0.96; p=0.03; I²= 0%; Grade of evidence: low). In OSR, obese patients (5.0%) had similar 30 day mortality to nonobese patients (5.7%) (OR 0.92; 95% CI 0.70-1.20; p=0.54; I²=0%; Grade of evidence: low). Wound complications were higher in obese patients undergoing OSR (OR 2.30; 95% CI 1.74-3.06; p<0.001; I²=0%; Grade of evidence: low). EVAR was associated with a lower 30 day mortality (1.5%) compared to OSR (5.0%) in obese patients (OR 0.23; 95% CI 0.12-0.46; p<0.001; I²= 38%; Grade of evidence: low). Cardiac, respiratory, wound, renal and neurological complications were also reduced in EVAR.

CONCLUSIONS

Obese patients have lower 30 day mortality in EVAR compared to nonobese patients. In OSR, obese patients had similar 30 day mortality but higher wound complications compared to nonobese patients. Obese patients otherwise have similar cardiopulmonary complication rates compared to nonobese patients in both EVAR and OSR. EVAR offers lower 30 day mortality and morbidity compared to OSR in obese patients. This study suggests that EVAR is superior to OSR in obese patients.

Association of body mass index with outcomes after thoracic endovascular aortic repair in the vascular quality initiative

OBJECTIVE

Although several studies have evaluated the impact of obesity on outcomes after abdominal aortic aneurysm repair, literature examining this association in thoracic endovascular aortic repair (TEVAR) is sparse. Here, we use a multi-institutional, international database to assess the role of body mass index (BMI) on adverse outcomes in patients who underwent TEVAR for descending thoracic aortic aneurysms (DTAA) and type B dissections (TBD).

METHODS

A retrospective review of all patients who underwent TEVAR for DTAA or TBD from August 2014 to August 2020 was performed. Patients who were underweight (BMI <18.5 kg/m²) or obese (BMI ≥30 kg/m²) were compared with those of normal weight (≥18.5 to <30 kg/m²). Adjustment for confounding was done with multivariable logistic regression or Cox proportional hazards regression as appropriate for studying postoperative or 1-year outcomes. Primary outcomes were 30-day and 1-year mortality. Other outcomes included any postoperative complication, stroke, and spinal cord ischemia.

RESULTS

A total of 3423 participants were included in the study, of whom 3.3% (n = 113) were underweight, 65.9% (n = 2253) had normal weight, and 30.8% (n = 1053) were obese. Compared with normal weight, there was no significant difference in 30-day mortality in underweight patients (odds ratio [OR], 1.81; 95% confidence interval [CI], 0.80-4.14; P = .156). Obese patients who underwent TEVAR for TBD had a 2.7-fold increase in the odds of 30-day mortality compared with normal weight (OR, 2.67; 95% CI, 1.52-4.68; P = .001). Obese and normal weight patients with DTAA had equivalent odds of 30-day mortality (OR, 1.32; 95% CI, 0.79-2.23; P = .292). The adjusted hazard of 1-year mortality was 2-fold higher in underweight patients compared with normal weight (hazard ratio, 2.15; 95% CI, 1.41-3.29; P < .001), driven by a higher risk of mortality among patients with thoracic aortic aneurysm (OR, 2.62; 95% CI, 1.63-4.21; P < .001). There was no significant difference in 1-year mortality risk between normal weight and obesity in both DTAA (OR, 0.77; 95% CI, 0.54-1.09; P = .146) and TBD (OR, 1.26; 95% CI, 0.85-1.86; P = .248).

CONCLUSIONS

In this study, obese patients who underwent TEVAR for DTAA had comparable 30-day and 1-year mortality risk as normal weight individuals. Obese patients who underwent TEVAR for TBD demonstrated a 2.7-fold increase in the odds of 30-day mortality, but equivalent mortality risk as normal weight patients at 1 year. TEVAR represents a safe minimally invasive option for treatment of DTAA in obese patients. Future work should be directed toward minimizing perioperative mortality among patients with TBD to optimize TEVAR outcomes.

Association Between Body Mass Index and Perioperative Mortality After Repair of Ruptured Abdominal Aortic Aneurysms

OBJECTIVE

The attempt to repair a ruptured abdominal aortic aneurysm carries a significant risk of perioperative mortality. The relationship between body mass index (BMI) and outcomes after repair of ruptured abdominal aortic aneurysms (AAAs) has not been well defined. We report the association of BMI with outcomes after ruptured AAA repair.

METHODS

Patients undergoing ruptured AAA repairs between 2008 and 2017 at 2 tertiary academic centers were included in this retrospective study. Demographics (including BMI), type of repair, length of stay, and admission mortality risk scores were gathered and analyzed using bivariate and multivariate logistic regressions. Adjusted odds ratio (AOR) was reported with 95% CIs and P values from the multivariate analysis. The primary outcome was 30-day mortality. Akaike information criterion (AIC) and c-statistics were used to assess the predictive power of models including physiologic score with or without BMI.

RESULTS

A total of 202 patients underwent repair of ruptured AAA. In bivariate relationship, increased BMI was significantly associated with 30-day mortality. With multivariate analysis, adjusting for demographics, type of procedure, and physiologic score, for each kg/m² increase in BMI, an 8% increase in the likelihood of perioperative mortality (AOR = 1.08, 95% CI: 1.01-1.17; P = .04) was observed.

CONCLUSION

When adjusted for admission risk score, type of procedure, and demographics, obesity was associated with increased 30-day mortality. With BMI as an additional data point, the c-statistics and AIC comparisons indicated that we would have a greater ability to preoperatively estimate mortality after ruptured AAA repair. Consideration could be made to include BMI in future mortality risk scoring systems for ruptured AAA.

Open Abdominal Aortic Aneurysm Repair Is Associated with Higher Mortality Among Nonobese Patients and Higher Risk of Deep Wound Infections Among Obese Patients

BACKGROUND

Prevalence of obesity in the United States is increasing. The impact of obesity on outcomes after endovascular and open abdominal aortic aneurysm (AAA) repair is largely unknown. The purpose of this analysis was to compare the postoperative outcomes between obese and nonobese patients after these operations.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from years 2013-2015 was analyzed. Preoperative, intraoperative, and postoperative variables were compared between obese and nonobese patient groups. Then obese and nonobese patients were divided into 2 groups each, based on the type of surgery (endovascular repair of abdominal aortic aneurysms (EVAR) versus. open AAA repair), and the outcomes were compared. Then multivariant analysis was used to compare impact of operative modality on outcomes for obese and nonobese patients.

RESULTS

A total of 6,859 patients (men 80%, women 20%) underwent surgical procedures for AAA during this time period. Among these patients, 2,218 (32.3%) had body mass index (BMI) ≥30, and 4,641 (67.7%) had BMI <30. Obese patients were less likely to be > 80 years old, women, nonwhites, and smokers. Obese patients had lower mortality and higher risk of deep wound infections after surgery (P < 0.05). Among the obese patients, 83.1% underwent EVAR and 16.9% underwent open AAA repair; patients undergoing EVAR had shorter operative times, shorter length of hospital stays, and mortality (P < 0.05). Among nonobese patients, 81% underwent EVAR and 19% underwent open AAA repair. Patients undergoing EVAR had shorter duration of operation, length of hospital stay, and mortality (P < 0.05). Overall, mortality was the highest among nonobese patients undergoing open AAA repair (odds ratio (OR) 0.66, confidence interval (CI) 0.44-0.99, P < 0.05). Incidence of deep wound infections was the highest among obese patients undergoing open AAA repair (OR 4.3, CI: 1.2-14.6, P < 0.05).

CONCLUSIONS

Nonobese patients have high mortality after open AAA repair, and obese patients have higher incidence of deep wound infections after open AAA repair. For patients deemed appropriate anatomic candidates, EVAR should be preferred for nonobese patients to improve mortality and for obese patients to reduce the incidence of deep wound infections.

Survival, cardiovascular morbidity, and reinterventions after elective endovascular aortic aneurysm repair in patients with and without diabetes: A nationwide propensity-adjusted analysis

Epidemiological data indicate decreased risk for development and growth of abdominal aortic aneurysm (AAA) among patients with diabetes mellitus (DM). On the other hand, DM adds to increased cardiovascular (CV) morbidity and mortality. In a nationwide observational cohort study of patients registered in the Swedish Vascular Register and the Swedish National Diabetes Register, we evaluated potential effects of DM on total mortality, CV morbidity, and the need for reintervention after elective endovascular aneurysm repair (EVAR) for AAA. We compared 748 patients with and 2630 without DM with propensity score-adjusted analysis, during a median 4.22 years of follow-up for patients with DM, and 4.05 years for those without. In adjusted analysis, diabetic patients showed higher rates of acute myocardial infarction (AMI) during follow-up (relative risk (RR) 1.44, 95% CI 1.06-1.95; p = 0.02), but lower need for reintervention (RR 0.12, CI 0.02-0.91; p = 0.04). There were no differences in total (RR 0.88, CI 0.74-1.05; p = 0.15) or CV (RR 1.58, CI 0.87-2.86; p = 0.13) mortality, or stroke (RR 0.95, CI 0.68-1.32; p = 0.75) during follow-up. In conclusion, patients with DM had higher rates of AMI and lower need for reintervention after elective EVAR than those without DM, whereas neither total nor CV mortality differed between groups. The putative protective effects of DM towards further AAA enlargement and late sac rupture may help explain the lower need for reintervention and absence of excess mortality.