- Email: [email protected]
Obesity is Not an Independent Factor for Adverse Outcome after Abdominal Aortic Aneurysm Repair
Obesity is Not an Independent Factor for Adverse Outcome after Abdominal Aortic Aneurysm Repair Lucie Salomon du Mont,1,2 Frederic Mauny,2,3 Nicolas Chretien,4 Caroline Kazandjan,4 Caroline Bourgeot,4 Valentin Crespy,4 Nicolas Abello,5 Simon Rinckenbach,1,6 and Eric Steinmetz,4 Besanc¸ on and Dijon, France
Background: The prevalence of obesity is increasing, and its impact on the outcome of open and endovascular abdominal aortic aneurysm (AAA) repair remains unclear, particularly in the European population. We herein assessed the impact of obesity on the postoperative course for both techniques. Methods: From a database that consecutively collects all patients undergoing AAA repair; we selected all patients undergoing elective surgery for open or endovascular AAA repair, between January 2003 and December 2011. We considered obese patients (body mass index >30 kg/ m2), overweight (25.1e30 kg/m2), and normal-weight patients (18.7e25 kg/m2), and compared mortality and/or severe complications at 30 days between obese and nonobese patients (overweight and normal weight) separately for each type of surgery by logistic regression analysis. We analyzed wound complications in the 2 groups. Results: We included 748 patients, 174 obese, and 574 nonobese patients. Obese patients were younger (P < 0.001) and were less likely to have renal failure (P < 0.001) in both techniques. Obese patients in the open repair (OR) group showed a trend toward lower mortality and/or complication rates than in nonobese patients (4.8% vs. 7.5%, P ¼ 0.34). In contrast, in the endovascular aortic aneurysm repair (EVAR) group, obese patients showed a trend toward higher mortality and/or complication rates than nonobese patients (7.1% vs. 3.2%, P ¼ 0.17). In multivariate analysis, obesity was not an independent predictor of outcomes in OR (P ¼ 0.18) or in EVAR (P ¼ 0.20). Wound complications were not higher in obese patients in OR and in EVAR. Conclusions: Obesity should not be considered an independent risk factor of death and severe complications at 30 days in either open or endovascular AAA repair. Therefore, obesity should not systematically lead to the decision to use EVAR.
INTRODUCTION The prevalence of obesity is steadily increasing in Western countries and particularly in North America.1 The impact of obesity on outcomes after vascular surgery has thus mainly been studied in the North American population, with controversial results: some series have suggested that obesity had no 1
Service de chirurgie vasculaire, CHRU Besanc¸ on, Besanc¸ on, France.
2
Universite de Franche-Comte, unite de recherche UMR 6249 ‘‘Chrono-environnement’’, Besanc¸ on, France. 3 Centre de methodologie Clinique, CHRU de BESANCON, Besanc¸ on, France. 4 Service de chirurgie cardio-vasculaire et thoracique, CHU Le Bocage, Dijon, France. 5 Direction de la recherche clinique et de l’innovation, CHU Le Bocage, Dijon, France.
effect,2e5 others showed, on the contrary, that it was associated with increased perioperative morbidity.6 In 2 large American cohorts,7,8 no overall independent effect of obesity on mortality after aortic surgery was found. However, after conducting subgroup analyses, extreme obesity appeared to be a risk factor for mortality and postoperative complications at 30 days, when patients were treated with 6 Universite de Franche-Comte, EA4268 INSERM, Besanc¸ on, France. Correspondence to: Lucie Salomon du Mont, MD, Service de chirurgie vasculaire, CHRU Besanc¸ on, H^opital Jean Minjoz, 2 Boulevard Fleming, Besanc¸ on 25030, France; E-mail: [email protected]
Ann Vasc Surg 2016; 33: 67–74 http://dx.doi.org/10.1016/j.avsg.2015.12.002 Ó 2016 Elsevier Inc. All rights reserved. Manuscript received: August 27, 2015; manuscript accepted: December 25, 2015; published online: January 22, 2016.
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68 Salomon du Mont et al.
open repair (OR). The number of patients treated using endovascular surgery has recently increased, and the impact of endovascular surgery compared with open surgery on outcomes in obese patients has yet to be clarified. In France, from 2001 to 2009, the ad hoc health agency Agence Francaise de Securite Sanitaire des Produits de Sant e9 defined different high-risk criteria, which led to a preference for endovascular aortic aneurysm repair (EVAR). Obesity was not one of these criteria, although some authors believe that it could be a good selection criterion for EVAR. Currently, the only restrictive criterion for EVAR is the anatomic feasibility. There are also more and more obese patients who are young. One recent meta-analysis, which included 4 retrospective registry-based studied comparing EVAR with OR, suggested that in obese patients EVAR was superior to OR with regard to death or major complications.10 But the monitoring and outcomes of OR and EVAR are not the same; so it is important to know the impact of obesity on outcomes of these 2 types of treatment and not to propose systematically EVAR to obese patients. Furthermore, the characteristics of obese populations significantly differ between North America11 and Europe with a lower prevalence of the disease, a lower body mass index (BMI) and lower levels of morbidity in the European population.12 The results of aortic surgery in obese European patients could differ from those in North American obese patients, although no such comparison has ever been published. One case control study in a European population compared outcomes after EVAR in obese and nonobese patients, and no difference was reported.13 The primary outcome in this study was all-cause mortality and obesity had not an independent impact on mortality after EVAR. The aim of the present study was to assess the impact of obesity on the short-term results (death or major complications at 30 days) in open aortic aneurysm surgery and EVAR.
METHODS The database used for this work has already been described in a previous study.14 Briefly, this prospective database includes all abdominal aortic aneurysms (AAA) treated in our department of vascular surgery since 1999 and was approved by our local ethics committee. All patients were operated in the same center. Here, we retrospectively studied a series of consecutive patients who underwent elective surgery for AAA from January 2003
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to December 2011. We excluded AAAs before 2003 because EVAR was less frequently used in our department before 2003. Patients were excluded if they presented ruptured AAA, if they presented a thoracoabdominal aneurysm or if the BMI was not available. Preoperative demographic and comorbidity variables were recorded for each patient. Weight was classified according to BMI (kg/m2) and the World Health Organization15 definitions of underweight (18.6 kg/m2), normal weight (18.7e25 kg/m2), overweight (25.1e30 kg/m2), obese class I (30.1e35 kg/m2), obese class II (35.1e40 kg/m2), and obese class III (>40 kg/m2). Obesity overall included obese classes IeIII. For this study, underweight patients were excluded, they brought heterogeneity because underweight was a risk factor of major complications.6,7 Overweight and normal weight patients were grouped together for the analyses. Hyperlipidemia and hypertension were defined by history. Chronic renal insufficiency was defined as preoperative creatinine clearance <60 mL/min. The demographic characteristics (cardiovascular risk factors and medical history), the BMI, the confounding factors of morbidity and mortality (age, peripheral vascular disease [PVD], heart disease, kidney disease, and gender),16 the medical treatment (statin use, anticoagulation, and antiplatelet), the operative data (operative time, blood loss, and length of stay in the intensive care unit), the period of the surgery (before and after 2010), the length of hospital stay, the postoperative complication rate, and the postoperative death rate were analyzed. The primary end point was a composite end point, defined by Chaikof et al.17 as the occurrence of death and/or severe complications at 30 days. A major complication was defined as a major surgical or medical intervention that may be associated with prolonged convalescence, that is usually accompanied by prolonged or permanent disability, and that may result in death. There were 3 types of complications: deploymentrelated complications (included access site complications: hematoma, false aneurysm, lymphocele, lymphorrhea, lymphedema, and infection), implant-related complications (graft infection, graft ruptured, or obstruction), and systemic complications (cardiac, pulmonary, renal insufficiency, cerebrovascular, deep venous thrombosis, pulmonary embolism, coagulopathy, bowel ischemia, spinal cord ischemia, and erectile dysfunction). Every complication was defined as mild, moderate, and severe complication. We analyzed too every wound complications.
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Influence of obesity on AAA repair 69
Statistical Analysis We analyzed the 2 types of surgery, EVAR or conventional OR, separately. Qualitative variables were expressed as numbers (percentages). Quantitative variables were expressed as means and standard deviations when normally distributed. Student’s t-test and the chi-squared test were used to compare patients’ characteristics in the 2 groups (obese or not) for each type of surgery when appropriate. Stepwise logistic regression was used for the multivariate analysis. Variables with a P value < 0.2 in the univariate analysis were introduced in the multivariate model. In all cases, obesity and confounding factors were included. The significance threshold was set at 0.05. Analyses were performed using SAS 9.03 software (SAS Institute, Cary, NC).
1070 paƟents 244 paƟents
PaƟents before 2003 excluded
826 paƟents PaƟents with BMI missing excluded
63 paƟents 763 paƟents
ATA excluded
6 paƟents
757 paƟents PaƟents with BMI<18.5
9 paƟents 748 paƟents
Open repair 493 paƟents
EVAR 255 paƟents
Fig. 1. Flow chart of the study.
RESULTS Populations For the 9-year period, 826 patients underwent AAA repair and 748 patients were finally included (Fig. 1). Underweight patients were not included in the final analysis, because there were very few (n ¼ 9). Patients’ characteristics are summarized in Table I. Compared with OR, the EVAR group was older (P < 0.001) and had more comorbidity: arrhythmia (P < 0.001), renal failure (P < 0.001), respiratory failure (P < 0.001), and heart failure (P < 0.001). There was a greater proportion of obese patients in the EVAR group (27.4% vs. 21.1%, P ¼ 0.05), but the distributions of the 5 classes of BMI in the OR and EVAR groups were no different (P ¼ 0.25; Fig. 2). General anesthesia was used in all cases. Median operative times (176 min vs. 149 min, P < 0.001) and blood loss (1375 mL vs. 384 mL, P < 0.001) were higher in OR than EVAR. Hospital length of stay was similar for the 2 types of surgery (9.4 days vs. 9.5 days, P ¼ 0.9). OR Comparisons of obese and nonobese patients’ characteristics are summarized in Table II. Obese patients were younger (P < 0.001), were more likely to have diabetes (P < 0.001) and hyperlipidemia (P ¼ 0.01) but less likely to have renal failure (P < 0.001). Obese patients lost more blood (1299 mL for nonobese vs. 1663 mL for obese, P ¼ 0.003). Twelve (16.2%) obese patients were operated by OR since 2010 vs. 92 (22.0%) before 2010 (P ¼ 0.26). Hospital length of stay for the obese
Table I. Demographic characteristics and cardiovascular risk factors of patients undergoing abdominal aneurysm repair
Age, yearsa Female gender BMIa Obesity Hypertension Hyperlipidemia Current smoking Diabetes mellitus Heart failure Coronary artery disease Prior myocardial infarction Arrhythmia Renal failure Respiratory failure PVD Prior surgery for PVD Statin Anticoagulant Antiplatelet a
Open, n ¼ 493, n (%)
EVAR, n ¼ 255, n (%)
P value
70.4 36 27.2 104 380 382 387 112 29 159
76.6 23 27.6 70 197 178 189 62 56 98
<0.001 0.41 0.24 0.05 0.95 0.02 0.18 0.62 <0.001 0.09
(8.1) (7.3) (4.2) (21.1) (77.1) (77.5) (78.5) (22.7) (5.9) (32.2)
62 (12.6) 82 151 56 72 28
(16 .6) (30.6) (11.4) (14.6) (5.7)
150 (30.4) 98 (19.9) 221 (44.8)
(7.9) (9.0) (4.0) (27.4) (77.2) (69.8) (74.1) (24.3) (22.0) (38.4)
39 (15.3) 70 131 58 28 25
(27.4) (51.4) (22.7) (11.0) (9.4)
68 (26.7) 69 (27.1) 109 (42.7)
0.30 <0.001 <0.001 <0.001 0.16 0.04 0.28 0.02 0.59
Expressed as mean (standard deviation).
group was similar to that for the nonobese group (9.3 vs. 10.0 days, P ¼ 0.68). The hospital stay was the same before and after 2010 (9.5 days vs. 7.4, P ¼ 0.06).
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Fig. 2. Body mass index distribution among the population in the (A) open surgery and (B) endovascular aneurysm repair groups (P ¼ 0.25).
The overall incidence of death and/or severe complications at 30 days was 6.9% (n ¼ 34). Mortality and morbidity in obese patients were not statistically different from those in nonobese patients. Death and/or severe complications were 7.5% in nonobese patients and 4.8% in obese patients (P ¼ 0.34). Mortality tended to be lower in obese patients (1% vs. 4.1%, P ¼ 0.07), whereas morbidity in obese patients was similar to that in nonobese patients (3.8% vs.
3.4%, P ¼ 0.31). Among the 34 patients with complications, systemic complications occurred in 23 patients (20 obese and 3 nonobese) and were pulmonary complications (n ¼ 10), bowel ischemia (n ¼ 10), and cardiac complications (n ¼ 3). There were 16 implant-related complications (1 obstruction graft, 14 hemorrhage, and 1 thromboembolic). Ten obese patients (9.62%) had a wound complication vs. 28 (7.20%) nonobese (P ¼ 0.41).
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Influence of obesity on AAA repair 71
Table II. Comparison of overweight and normalweight patients with obese patients undergoing OR for abdominal aneurysm Overweight and normal weight, Obese, n (%) n (%) a
Age, years 71.1 (8.1) Female gender 29 (7.5) Hypertension 297 (76.3) Hyperlipidemia 292 (75.1) Current smoking 301 (77.4) Heart failure 22 (5.7) Coronary artery 124 (31.9) disease Prior myocardial 45 (11.6) infarction Arrhythmia 60 (15.4) Renal failure 137 (35.2) Respiratory failure 40 (10.3) PVD 58 (14.9) a
67.8 7 83 90 86 7 35
22 14 16 14
P value
(7.6) <0.001 (6.7) 0.80 (79.8) 0.46 (86.5) 0.01 (82.7) 0.24 (6.7) 0.68 (33.6) 0.73
17 (16.3)
(21.1) 0.16 (13.5) <0.001 (15.4) 0.14 (13.5) 0.71
Table III. Risk factors of death and/or severe complications at 30 days in the open surgery group (n ¼ 493) bivariate analyses
Age, yearsa 70.2 (8.1) Female gender 31 (6.75) Obesity 99 (21.6) Hypertension 349 (76.0) Hyperlipidemia 357 (77.8) Current smoking 89 (19.4) Diabetes mellitus 103 (22.4) Coronary artery 142 (30.9) disease Prior myocardial 59 (12.8) infarction Arrhythmia 77 (16.8) Renal failure 137 (29.8) Respiratory failure 51 (11.1) PVD 61 (13.3) a
Death or severe complications n ¼ 34, n (%) P value
72.7 5 5 31 25 6 9 17
(7.5) (14.7) (14.7) (91.9) (73.5) (17.6) (26.5) (50.0)
3 (8.8) 5 14 5 11
(14.7) (41.2) (14.7) (32.3)
PVD Coronary artery disease Obesity
0.08 0.08 0.34 0.04 0.56 0.80 0.59 0.02 0.19 0.75 0.17 0.52 0.002
Expressed as mean (standard deviation).
Factors associated with death or severe complications are summarized in Table III. Multivariate analysis adjusted for age, sex, hypertension, heart failure, and renal failure (Table IV) demonstrated that coronary heart disease, and PVD were factors associated with severe complications after open surgery, whereas obesity was not a risk factor (P ¼ 0.18).
P value
OR (95% CI)
0.004 0.02 0.18
0.32 (0.15; 0.70) 0.43 (0.21; 0.88) 0.44 (1.13; 1.48)
Table V. Comparison of obese and nonobese patients undergoing EVAR
0.19
Expressed as mean (standard deviation).
Neither death nor severe complications n ¼ 459, n (%)
Table IV. Risk factors of death and/or severe complications at 30 days in the open surgery group (n ¼ 493) multivariate analyses adjusted by age, gender, hypertension, heart failure, and renal failure
Age, yearsa Female gender Hypertension Hyperlipidemia Current smoking Heart failure Coronary artery disease Prior myocardial infarction Arrhythmia Renal failure Respiratory failure PVD a
Nonobese, n (%)
Obese, n (%)
77.3 17 139 127 136 39 75
74.8 6 58 51 53 17 23
(8.0) (9.2) (75.1) (68.6) (73.5) (21.1) (40.5)
32 (17.3) 50 112 40 23
(27.0) (60.6) (21.6) (12.4)
P value
(7.5) (8.6) (82.9) (72.9) (75.7) (24.3) (32.9)
0.03 0.88 0.19 0.51 0.72 0.58 0.26
7 (10.0)
0.15
20 19 18 5
(28.6) (27.1) (25.7) (7.1)
0.80 <0.001 0.49 0.23
Expressed as mean (standard deviation).
EVAR The characteristics of obese and nonobese patients are summarized in Table V. Obese patients were younger (P ¼ 0.03) and were less likely to have renal failure (P < 0.001). Twenty-two (36.1%) obese patients were operated by EVAR since 2010 vs. 48 (24.7%) before 2010 (P ¼ 0.08). Median operative times, blood loss, and hospital length of stay were similar in obese and nonobese patients (hospital stay 9.6 vs. 9.0, P ¼ 0.57). The hospital stay was higher before 2010 versus after (9.8 days vs. 5.8 days, P ¼ 0.0004). Death and/or severe complications at 30 days occurred in 4.3% (n ¼ 11) of patients. Death and/ or severe complications occurred in 3.2% of nonobese patients and in 7.1% of obese patients (P ¼ 0.17). The mortality rate was 2.2% vs. 2.8% (P ¼ 0.31) and morbidity 1% vs. 4.3% (P ¼ 0.1) in the nonobese and obese group, respectively. The major complications were because of implantrelated complications in 6 cases and systemic
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Table VI. Risk factors of death and/or severe complication at 30 days in the EVAR population (n ¼ 155) bivariate analysis Neither death nor severe Death or severe complications complications P n ¼ 244, n (%) n ¼ 11, n (%) value
Age, yearsa 76.8 (8.0) Female gender 21 (8.6) Obese 65 (26.6) Hypertension 188 (73.7) Hyperlipidemia 172 (70.5) Current smoking 35 (14.3) Diabetes mellitus 60 (24.6) Coronary artery 95 (38.9) disease Arrhythmia 67 (27.5) Renal failure 126 (51.6) Respiratory failure 55 (22.5) PVD 27 (11.1) a
78.8 2 5 9 6 0 2 3
(5.0) (18.2) (45.4) (81.8) (54.6) (0) (18.2) (27.3)
0.34 0.19 0.17 0.29 0.26 0.19 0.27 0.19
3 5 3 1
(27.3) (45.4) (27.3) (9.1)
0.27 0.69 0.25 0.38
Expressed as mean (standard deviation).
complications in 5 cases (1 bowel ischemia, 2 cardiac and 2 pulmonary diseases). Three obese patients (4.3%) had a wound complication vs. 22 (11.9%) nonobese (P ¼ 0.06). Factors associated with death or severe complications are summarized in Table VI. There were no risk factors in the bivariate analysis. The multivariate analysis was adjusted for confounding factors: current smoking, coronary artery disease, and obesity. There were no multivariate factors of death or severe complications in EVAR. Obesity was not an independent predictor of outcomes (P ¼ 0.20) in the multivariate analysis. Obese versus Nonobese Table VII presents comparisons of postoperative events in obese and nonobese patients. In nonobese patients, postoperative complication rates were higher in OR than EVAR (7.5% vs. 3.2%, P ¼ 0.04), whereas for obese patients, complication rates tended to be lower in OR (4.8% vs. 7.1%, P ¼ 0.52).
DISCUSSION EVAR conferred a benefit over OR of cardiovascular morbidity18e21; then EVAR was often prefer to OR for AAA in obese patients, who more to suffer from such morbidity. But this choice was not supported by scientific evidence. The main result of our study was that obese patients are no more likely than nonobese patients to suffer severe
complications in the short-term after OR or EVAR. In obese patients, the occurrence of death and severe complications tended to be higher in the EVAR group than the OR group, but the difference was not statistically significant. Opposite results were observed in overweight and normal-weight patients, which is consistent with previous studies.22,23 The choice to analyze the 2 types of surgery separately was made for several reasons. First, the characteristics of the 2 surgery groups were supposed to be different, given the active selection process conducted by the surgeon himself, who preferred EVAR for high-risk patients. As a result, the 2 populations of patients could not be considered homogeneous because until 2009 EVAR was privilege for high-risk patients,9 and the anatomy had to be suitable for EVAR. Second, the results of aortic surgery significantly differ depending the technique used: EVAR or OR,22,23 which could influence the analysis of the postoperative period. And we wanted to avoid making a second-step subgroup analysis. Although EVAR has been available in our department since 1999, few EVAR procedures were done between 1999 and 2003, and this technique was considered usual only after 2003. Thus, to avoid bias because of the learning curve for EVAR, only patients included after 2003 were considered in the present study. Underweight patients were not included in the final analysis because underweight has been identified as a risk factor for postoperative complications in aortic surgery6,7 and could have impacted the statistical link between obesity and postoperative prognosis. The prevalence of obesity was higher in our cohort than that usually observed in the overall French population: 10%.24 This observation could be explained by the well-documented impact of obesity on the occurrence of cardiovascular diseases. On this point, our study differs from previous studies in the North American population, which did not describe a higher prevalence of obesity in patients undergoing surgical aortic aneurysm repair than in the general population. Not surprisingly, there was a lower proportion of morbidly obese patients in our cohort than in American studies.11,12,25 In our cohort, the impact of obesity on the perioperative prognosis in the EVAR group seemed to be different from that in the OR group. The occurrence of death and severe complications tended to be higher in overweight and normal-weight patients than in obese patients in the OR group, but the difference was not statistically significant. This observation could be explained by the impact of age and chronic kidney disease on the prognosis
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Influence of obesity on AAA repair 73
Table VII. Comparison of postoperative death and severe complications between OR and EVAR for obese and nonobese patients Morbimortality
Obese Open (n ¼ 104) EVAR (n ¼ 70) Nonobese Open (n ¼ 393) EVAR (n ¼ 190)
Mortality
Morbidity
%
P value
%
P value
%
P value
4.8 7.1
0.52
1.0 2.8
0.29
3.8 4.3
0.30
7.5 3.2
0.04
4.1 2.2
0.23
3.4 1.0
0.06
of patients who underwent OR. In our study, obese patients were younger and less likely to have chronic renal insufficiency than were nonobese patients. Hyperlipidemia and diabetes mellitus were more frequent in obese patients in the OR group. The hyperlipidemia treatment could have played a protective role.26 Moreover, diabetes mellitus is not a recognized risk factor after OR.27 There was a trend to have more patients obese in EVAR group after 2010, this patient had less morbidity (age and chronic kidney disease) than nonobese patients. Therefore, our results do not, unfortunately, help surgeons to identify the type of surgical procedure that might be chosen in obese patients. However, our work does suggest that obesity should not systematically lead to the decision to use EVAR. Surprisingly, the mean operative time in OR was no higher in the obese group, but blood loss was greater. The hospital stay in OR seemed similar to that in EVAR; this is probably because there was a learning curve and until 2009 EVAR was used in high-risk patients,9 who could not be discharged quickly after the intervention. This could be explained because the hospital stay was higher before 2010 in EVAR group unlike OR group. Wound complications were not higher in obese patient. The main limit of our study was the lack of power concerning the impact of obesity on the prognosis. This was probably due the separate analyses in 2 groups, despite the large number of patients studied. It was a monocentric retrospective study. Populations of obese and nonobese patients were heterogen. But we have conducted a multivariable analysis to study the independent impact of obesity compared with known confounding factors.
CONCLUSIONS There was a trend to treat obese patients more and more by EVAR. But the main result of our study
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(EVAR trial 1), 30-day operative mortality results: randomised controlled trial. Lancet 2004;364:843e8. Cuypers PW, Gardien M, Buth J, et al. Randomized study comparing cardiac response in endovascular and open abdominal aortic aneurysm repair. Br J Surg 2001;88:1059e65. Becquemin J-P, Pillet J-C, Lescalie F, et al. A randomized controlled trial of endovascular aneurysm repair versus open surgery for abdominal aortic aneurysms in low- to moderate-risk patients. J Vasc Surg 2011;53:1167e73. Brown LC, Thompson SG, Greenhalgh RM, Endovascular Aneurysm Repair trial participants. Incidence of cardiovascular events and death after open or endovascular repair of abdominal aortic aneurysm in the randomized EVAR trial 1. Br J Surg 2011;98:935e42. Chambers D, Epstein D, Walker S, et al. Endovascular stents for abdominal aortic aneurysms: a systematic review and economic model. Health Technol Assess Winch Engl 2009;13:1e189. EVAR trial participants. Endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (EVAR trial 1): randomised controlled trial. Lancet 2005;365:2179e86. Maillard GC, Thibult N, Forhan A. Evolution des prevalences du surpods et de l’obesite entre 1980 et 1991 dans deux echantillons representatitfs des menages franc¸ais. INSEE, 1997. Kuczmarski RJ. Prevalence of overweight and weight gain in the United States. Am J Clin Nutr 1992;55:495Se502S. Schouten O, Boersma E, Hoeks SE, et al. Fluvastatin and perioperative events in patients undergoing vascular surgery. N Engl J Med 2009;361:980e9. Moll FL, Powell JT, Fraedrich G, et al. Management of abdominal aortic aneurysms clinical practice guidelines of the European society for vascular surgery. Eur J Vasc Endovasc Surg 2011;41:S1e58.
Background: The prevalence of obesity is increasing, and its impact on the outcome of open and endovascular abdominal aortic aneurysm (AAA) repair remains unclear, particularly in the European population. We herein assessed the impact of obesity on the postoperative course for both techniques. Methods: From a database that consecutively collects all patients undergoing AAA repair; we selected all patients undergoing elective surgery for open or endovascular AAA repair, between January 2003 and December 2011. We considered obese patients (body mass index >30 kg/ m2), overweight (25.1e30 kg/m2), and normal-weight patients (18.7e25 kg/m2), and compared mortality and/or severe complications at 30 days between obese and nonobese patients (overweight and normal weight) separately for each type of surgery by logistic regression analysis. We analyzed wound complications in the 2 groups. Results: We included 748 patients, 174 obese, and 574 nonobese patients. Obese patients were younger (P < 0.001) and were less likely to have renal failure (P < 0.001) in both techniques. Obese patients in the open repair (OR) group showed a trend toward lower mortality and/or complication rates than in nonobese patients (4.8% vs. 7.5%, P ¼ 0.34). In contrast, in the endovascular aortic aneurysm repair (EVAR) group, obese patients showed a trend toward higher mortality and/or complication rates than nonobese patients (7.1% vs. 3.2%, P ¼ 0.17). In multivariate analysis, obesity was not an independent predictor of outcomes in OR (P ¼ 0.18) or in EVAR (P ¼ 0.20). Wound complications were not higher in obese patients in OR and in EVAR. Conclusions: Obesity should not be considered an independent risk factor of death and severe complications at 30 days in either open or endovascular AAA repair. Therefore, obesity should not systematically lead to the decision to use EVAR.
INTRODUCTION The prevalence of obesity is steadily increasing in Western countries and particularly in North America.1 The impact of obesity on outcomes after vascular surgery has thus mainly been studied in the North American population, with controversial results: some series have suggested that obesity had no 1
Service de chirurgie vasculaire, CHRU Besanc¸ on, Besanc¸ on, France.
2
Universite de Franche-Comte, unite de recherche UMR 6249 ‘‘Chrono-environnement’’, Besanc¸ on, France. 3 Centre de methodologie Clinique, CHRU de BESANCON, Besanc¸ on, France. 4 Service de chirurgie cardio-vasculaire et thoracique, CHU Le Bocage, Dijon, France. 5 Direction de la recherche clinique et de l’innovation, CHU Le Bocage, Dijon, France.
effect,2e5 others showed, on the contrary, that it was associated with increased perioperative morbidity.6 In 2 large American cohorts,7,8 no overall independent effect of obesity on mortality after aortic surgery was found. However, after conducting subgroup analyses, extreme obesity appeared to be a risk factor for mortality and postoperative complications at 30 days, when patients were treated with 6 Universite de Franche-Comte, EA4268 INSERM, Besanc¸ on, France. Correspondence to: Lucie Salomon du Mont, MD, Service de chirurgie vasculaire, CHRU Besanc¸ on, H^opital Jean Minjoz, 2 Boulevard Fleming, Besanc¸ on 25030, France; E-mail: [email protected]
Ann Vasc Surg 2016; 33: 67–74 http://dx.doi.org/10.1016/j.avsg.2015.12.002 Ó 2016 Elsevier Inc. All rights reserved. Manuscript received: August 27, 2015; manuscript accepted: December 25, 2015; published online: January 22, 2016.
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68 Salomon du Mont et al.
open repair (OR). The number of patients treated using endovascular surgery has recently increased, and the impact of endovascular surgery compared with open surgery on outcomes in obese patients has yet to be clarified. In France, from 2001 to 2009, the ad hoc health agency Agence Francaise de Securite Sanitaire des Produits de Sant e9 defined different high-risk criteria, which led to a preference for endovascular aortic aneurysm repair (EVAR). Obesity was not one of these criteria, although some authors believe that it could be a good selection criterion for EVAR. Currently, the only restrictive criterion for EVAR is the anatomic feasibility. There are also more and more obese patients who are young. One recent meta-analysis, which included 4 retrospective registry-based studied comparing EVAR with OR, suggested that in obese patients EVAR was superior to OR with regard to death or major complications.10 But the monitoring and outcomes of OR and EVAR are not the same; so it is important to know the impact of obesity on outcomes of these 2 types of treatment and not to propose systematically EVAR to obese patients. Furthermore, the characteristics of obese populations significantly differ between North America11 and Europe with a lower prevalence of the disease, a lower body mass index (BMI) and lower levels of morbidity in the European population.12 The results of aortic surgery in obese European patients could differ from those in North American obese patients, although no such comparison has ever been published. One case control study in a European population compared outcomes after EVAR in obese and nonobese patients, and no difference was reported.13 The primary outcome in this study was all-cause mortality and obesity had not an independent impact on mortality after EVAR. The aim of the present study was to assess the impact of obesity on the short-term results (death or major complications at 30 days) in open aortic aneurysm surgery and EVAR.
METHODS The database used for this work has already been described in a previous study.14 Briefly, this prospective database includes all abdominal aortic aneurysms (AAA) treated in our department of vascular surgery since 1999 and was approved by our local ethics committee. All patients were operated in the same center. Here, we retrospectively studied a series of consecutive patients who underwent elective surgery for AAA from January 2003
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to December 2011. We excluded AAAs before 2003 because EVAR was less frequently used in our department before 2003. Patients were excluded if they presented ruptured AAA, if they presented a thoracoabdominal aneurysm or if the BMI was not available. Preoperative demographic and comorbidity variables were recorded for each patient. Weight was classified according to BMI (kg/m2) and the World Health Organization15 definitions of underweight (18.6 kg/m2), normal weight (18.7e25 kg/m2), overweight (25.1e30 kg/m2), obese class I (30.1e35 kg/m2), obese class II (35.1e40 kg/m2), and obese class III (>40 kg/m2). Obesity overall included obese classes IeIII. For this study, underweight patients were excluded, they brought heterogeneity because underweight was a risk factor of major complications.6,7 Overweight and normal weight patients were grouped together for the analyses. Hyperlipidemia and hypertension were defined by history. Chronic renal insufficiency was defined as preoperative creatinine clearance <60 mL/min. The demographic characteristics (cardiovascular risk factors and medical history), the BMI, the confounding factors of morbidity and mortality (age, peripheral vascular disease [PVD], heart disease, kidney disease, and gender),16 the medical treatment (statin use, anticoagulation, and antiplatelet), the operative data (operative time, blood loss, and length of stay in the intensive care unit), the period of the surgery (before and after 2010), the length of hospital stay, the postoperative complication rate, and the postoperative death rate were analyzed. The primary end point was a composite end point, defined by Chaikof et al.17 as the occurrence of death and/or severe complications at 30 days. A major complication was defined as a major surgical or medical intervention that may be associated with prolonged convalescence, that is usually accompanied by prolonged or permanent disability, and that may result in death. There were 3 types of complications: deploymentrelated complications (included access site complications: hematoma, false aneurysm, lymphocele, lymphorrhea, lymphedema, and infection), implant-related complications (graft infection, graft ruptured, or obstruction), and systemic complications (cardiac, pulmonary, renal insufficiency, cerebrovascular, deep venous thrombosis, pulmonary embolism, coagulopathy, bowel ischemia, spinal cord ischemia, and erectile dysfunction). Every complication was defined as mild, moderate, and severe complication. We analyzed too every wound complications.
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Influence of obesity on AAA repair 69
Statistical Analysis We analyzed the 2 types of surgery, EVAR or conventional OR, separately. Qualitative variables were expressed as numbers (percentages). Quantitative variables were expressed as means and standard deviations when normally distributed. Student’s t-test and the chi-squared test were used to compare patients’ characteristics in the 2 groups (obese or not) for each type of surgery when appropriate. Stepwise logistic regression was used for the multivariate analysis. Variables with a P value < 0.2 in the univariate analysis were introduced in the multivariate model. In all cases, obesity and confounding factors were included. The significance threshold was set at 0.05. Analyses were performed using SAS 9.03 software (SAS Institute, Cary, NC).
1070 paƟents 244 paƟents
PaƟents before 2003 excluded
826 paƟents PaƟents with BMI missing excluded
63 paƟents 763 paƟents
ATA excluded
6 paƟents
757 paƟents PaƟents with BMI<18.5
9 paƟents 748 paƟents
Open repair 493 paƟents
EVAR 255 paƟents
Fig. 1. Flow chart of the study.
RESULTS Populations For the 9-year period, 826 patients underwent AAA repair and 748 patients were finally included (Fig. 1). Underweight patients were not included in the final analysis, because there were very few (n ¼ 9). Patients’ characteristics are summarized in Table I. Compared with OR, the EVAR group was older (P < 0.001) and had more comorbidity: arrhythmia (P < 0.001), renal failure (P < 0.001), respiratory failure (P < 0.001), and heart failure (P < 0.001). There was a greater proportion of obese patients in the EVAR group (27.4% vs. 21.1%, P ¼ 0.05), but the distributions of the 5 classes of BMI in the OR and EVAR groups were no different (P ¼ 0.25; Fig. 2). General anesthesia was used in all cases. Median operative times (176 min vs. 149 min, P < 0.001) and blood loss (1375 mL vs. 384 mL, P < 0.001) were higher in OR than EVAR. Hospital length of stay was similar for the 2 types of surgery (9.4 days vs. 9.5 days, P ¼ 0.9). OR Comparisons of obese and nonobese patients’ characteristics are summarized in Table II. Obese patients were younger (P < 0.001), were more likely to have diabetes (P < 0.001) and hyperlipidemia (P ¼ 0.01) but less likely to have renal failure (P < 0.001). Obese patients lost more blood (1299 mL for nonobese vs. 1663 mL for obese, P ¼ 0.003). Twelve (16.2%) obese patients were operated by OR since 2010 vs. 92 (22.0%) before 2010 (P ¼ 0.26). Hospital length of stay for the obese
Table I. Demographic characteristics and cardiovascular risk factors of patients undergoing abdominal aneurysm repair
Age, yearsa Female gender BMIa Obesity Hypertension Hyperlipidemia Current smoking Diabetes mellitus Heart failure Coronary artery disease Prior myocardial infarction Arrhythmia Renal failure Respiratory failure PVD Prior surgery for PVD Statin Anticoagulant Antiplatelet a
Open, n ¼ 493, n (%)
EVAR, n ¼ 255, n (%)
P value
70.4 36 27.2 104 380 382 387 112 29 159
76.6 23 27.6 70 197 178 189 62 56 98
<0.001 0.41 0.24 0.05 0.95 0.02 0.18 0.62 <0.001 0.09
(8.1) (7.3) (4.2) (21.1) (77.1) (77.5) (78.5) (22.7) (5.9) (32.2)
62 (12.6) 82 151 56 72 28
(16 .6) (30.6) (11.4) (14.6) (5.7)
150 (30.4) 98 (19.9) 221 (44.8)
(7.9) (9.0) (4.0) (27.4) (77.2) (69.8) (74.1) (24.3) (22.0) (38.4)
39 (15.3) 70 131 58 28 25
(27.4) (51.4) (22.7) (11.0) (9.4)
68 (26.7) 69 (27.1) 109 (42.7)
0.30 <0.001 <0.001 <0.001 0.16 0.04 0.28 0.02 0.59
Expressed as mean (standard deviation).
group was similar to that for the nonobese group (9.3 vs. 10.0 days, P ¼ 0.68). The hospital stay was the same before and after 2010 (9.5 days vs. 7.4, P ¼ 0.06).
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Fig. 2. Body mass index distribution among the population in the (A) open surgery and (B) endovascular aneurysm repair groups (P ¼ 0.25).
The overall incidence of death and/or severe complications at 30 days was 6.9% (n ¼ 34). Mortality and morbidity in obese patients were not statistically different from those in nonobese patients. Death and/or severe complications were 7.5% in nonobese patients and 4.8% in obese patients (P ¼ 0.34). Mortality tended to be lower in obese patients (1% vs. 4.1%, P ¼ 0.07), whereas morbidity in obese patients was similar to that in nonobese patients (3.8% vs.
3.4%, P ¼ 0.31). Among the 34 patients with complications, systemic complications occurred in 23 patients (20 obese and 3 nonobese) and were pulmonary complications (n ¼ 10), bowel ischemia (n ¼ 10), and cardiac complications (n ¼ 3). There were 16 implant-related complications (1 obstruction graft, 14 hemorrhage, and 1 thromboembolic). Ten obese patients (9.62%) had a wound complication vs. 28 (7.20%) nonobese (P ¼ 0.41).
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Influence of obesity on AAA repair 71
Table II. Comparison of overweight and normalweight patients with obese patients undergoing OR for abdominal aneurysm Overweight and normal weight, Obese, n (%) n (%) a
Age, years 71.1 (8.1) Female gender 29 (7.5) Hypertension 297 (76.3) Hyperlipidemia 292 (75.1) Current smoking 301 (77.4) Heart failure 22 (5.7) Coronary artery 124 (31.9) disease Prior myocardial 45 (11.6) infarction Arrhythmia 60 (15.4) Renal failure 137 (35.2) Respiratory failure 40 (10.3) PVD 58 (14.9) a
67.8 7 83 90 86 7 35
22 14 16 14
P value
(7.6) <0.001 (6.7) 0.80 (79.8) 0.46 (86.5) 0.01 (82.7) 0.24 (6.7) 0.68 (33.6) 0.73
17 (16.3)
(21.1) 0.16 (13.5) <0.001 (15.4) 0.14 (13.5) 0.71
Table III. Risk factors of death and/or severe complications at 30 days in the open surgery group (n ¼ 493) bivariate analyses
Age, yearsa 70.2 (8.1) Female gender 31 (6.75) Obesity 99 (21.6) Hypertension 349 (76.0) Hyperlipidemia 357 (77.8) Current smoking 89 (19.4) Diabetes mellitus 103 (22.4) Coronary artery 142 (30.9) disease Prior myocardial 59 (12.8) infarction Arrhythmia 77 (16.8) Renal failure 137 (29.8) Respiratory failure 51 (11.1) PVD 61 (13.3) a
Death or severe complications n ¼ 34, n (%) P value
72.7 5 5 31 25 6 9 17
(7.5) (14.7) (14.7) (91.9) (73.5) (17.6) (26.5) (50.0)
3 (8.8) 5 14 5 11
(14.7) (41.2) (14.7) (32.3)
PVD Coronary artery disease Obesity
0.08 0.08 0.34 0.04 0.56 0.80 0.59 0.02 0.19 0.75 0.17 0.52 0.002
Expressed as mean (standard deviation).
Factors associated with death or severe complications are summarized in Table III. Multivariate analysis adjusted for age, sex, hypertension, heart failure, and renal failure (Table IV) demonstrated that coronary heart disease, and PVD were factors associated with severe complications after open surgery, whereas obesity was not a risk factor (P ¼ 0.18).
P value
OR (95% CI)
0.004 0.02 0.18
0.32 (0.15; 0.70) 0.43 (0.21; 0.88) 0.44 (1.13; 1.48)
Table V. Comparison of obese and nonobese patients undergoing EVAR
0.19
Expressed as mean (standard deviation).
Neither death nor severe complications n ¼ 459, n (%)
Table IV. Risk factors of death and/or severe complications at 30 days in the open surgery group (n ¼ 493) multivariate analyses adjusted by age, gender, hypertension, heart failure, and renal failure
Age, yearsa Female gender Hypertension Hyperlipidemia Current smoking Heart failure Coronary artery disease Prior myocardial infarction Arrhythmia Renal failure Respiratory failure PVD a
Nonobese, n (%)
Obese, n (%)
77.3 17 139 127 136 39 75
74.8 6 58 51 53 17 23
(8.0) (9.2) (75.1) (68.6) (73.5) (21.1) (40.5)
32 (17.3) 50 112 40 23
(27.0) (60.6) (21.6) (12.4)
P value
(7.5) (8.6) (82.9) (72.9) (75.7) (24.3) (32.9)
0.03 0.88 0.19 0.51 0.72 0.58 0.26
7 (10.0)
0.15
20 19 18 5
(28.6) (27.1) (25.7) (7.1)
0.80 <0.001 0.49 0.23
Expressed as mean (standard deviation).
EVAR The characteristics of obese and nonobese patients are summarized in Table V. Obese patients were younger (P ¼ 0.03) and were less likely to have renal failure (P < 0.001). Twenty-two (36.1%) obese patients were operated by EVAR since 2010 vs. 48 (24.7%) before 2010 (P ¼ 0.08). Median operative times, blood loss, and hospital length of stay were similar in obese and nonobese patients (hospital stay 9.6 vs. 9.0, P ¼ 0.57). The hospital stay was higher before 2010 versus after (9.8 days vs. 5.8 days, P ¼ 0.0004). Death and/or severe complications at 30 days occurred in 4.3% (n ¼ 11) of patients. Death and/ or severe complications occurred in 3.2% of nonobese patients and in 7.1% of obese patients (P ¼ 0.17). The mortality rate was 2.2% vs. 2.8% (P ¼ 0.31) and morbidity 1% vs. 4.3% (P ¼ 0.1) in the nonobese and obese group, respectively. The major complications were because of implantrelated complications in 6 cases and systemic
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Table VI. Risk factors of death and/or severe complication at 30 days in the EVAR population (n ¼ 155) bivariate analysis Neither death nor severe Death or severe complications complications P n ¼ 244, n (%) n ¼ 11, n (%) value
Age, yearsa 76.8 (8.0) Female gender 21 (8.6) Obese 65 (26.6) Hypertension 188 (73.7) Hyperlipidemia 172 (70.5) Current smoking 35 (14.3) Diabetes mellitus 60 (24.6) Coronary artery 95 (38.9) disease Arrhythmia 67 (27.5) Renal failure 126 (51.6) Respiratory failure 55 (22.5) PVD 27 (11.1) a
78.8 2 5 9 6 0 2 3
(5.0) (18.2) (45.4) (81.8) (54.6) (0) (18.2) (27.3)
0.34 0.19 0.17 0.29 0.26 0.19 0.27 0.19
3 5 3 1
(27.3) (45.4) (27.3) (9.1)
0.27 0.69 0.25 0.38
Expressed as mean (standard deviation).
complications in 5 cases (1 bowel ischemia, 2 cardiac and 2 pulmonary diseases). Three obese patients (4.3%) had a wound complication vs. 22 (11.9%) nonobese (P ¼ 0.06). Factors associated with death or severe complications are summarized in Table VI. There were no risk factors in the bivariate analysis. The multivariate analysis was adjusted for confounding factors: current smoking, coronary artery disease, and obesity. There were no multivariate factors of death or severe complications in EVAR. Obesity was not an independent predictor of outcomes (P ¼ 0.20) in the multivariate analysis. Obese versus Nonobese Table VII presents comparisons of postoperative events in obese and nonobese patients. In nonobese patients, postoperative complication rates were higher in OR than EVAR (7.5% vs. 3.2%, P ¼ 0.04), whereas for obese patients, complication rates tended to be lower in OR (4.8% vs. 7.1%, P ¼ 0.52).
DISCUSSION EVAR conferred a benefit over OR of cardiovascular morbidity18e21; then EVAR was often prefer to OR for AAA in obese patients, who more to suffer from such morbidity. But this choice was not supported by scientific evidence. The main result of our study was that obese patients are no more likely than nonobese patients to suffer severe
complications in the short-term after OR or EVAR. In obese patients, the occurrence of death and severe complications tended to be higher in the EVAR group than the OR group, but the difference was not statistically significant. Opposite results were observed in overweight and normal-weight patients, which is consistent with previous studies.22,23 The choice to analyze the 2 types of surgery separately was made for several reasons. First, the characteristics of the 2 surgery groups were supposed to be different, given the active selection process conducted by the surgeon himself, who preferred EVAR for high-risk patients. As a result, the 2 populations of patients could not be considered homogeneous because until 2009 EVAR was privilege for high-risk patients,9 and the anatomy had to be suitable for EVAR. Second, the results of aortic surgery significantly differ depending the technique used: EVAR or OR,22,23 which could influence the analysis of the postoperative period. And we wanted to avoid making a second-step subgroup analysis. Although EVAR has been available in our department since 1999, few EVAR procedures were done between 1999 and 2003, and this technique was considered usual only after 2003. Thus, to avoid bias because of the learning curve for EVAR, only patients included after 2003 were considered in the present study. Underweight patients were not included in the final analysis because underweight has been identified as a risk factor for postoperative complications in aortic surgery6,7 and could have impacted the statistical link between obesity and postoperative prognosis. The prevalence of obesity was higher in our cohort than that usually observed in the overall French population: 10%.24 This observation could be explained by the well-documented impact of obesity on the occurrence of cardiovascular diseases. On this point, our study differs from previous studies in the North American population, which did not describe a higher prevalence of obesity in patients undergoing surgical aortic aneurysm repair than in the general population. Not surprisingly, there was a lower proportion of morbidly obese patients in our cohort than in American studies.11,12,25 In our cohort, the impact of obesity on the perioperative prognosis in the EVAR group seemed to be different from that in the OR group. The occurrence of death and severe complications tended to be higher in overweight and normal-weight patients than in obese patients in the OR group, but the difference was not statistically significant. This observation could be explained by the impact of age and chronic kidney disease on the prognosis
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Influence of obesity on AAA repair 73
Table VII. Comparison of postoperative death and severe complications between OR and EVAR for obese and nonobese patients Morbimortality
Obese Open (n ¼ 104) EVAR (n ¼ 70) Nonobese Open (n ¼ 393) EVAR (n ¼ 190)
Mortality
Morbidity
%
P value
%
P value
%
P value
4.8 7.1
0.52
1.0 2.8
0.29
3.8 4.3
0.30
7.5 3.2
0.04
4.1 2.2
0.23
3.4 1.0
0.06
of patients who underwent OR. In our study, obese patients were younger and less likely to have chronic renal insufficiency than were nonobese patients. Hyperlipidemia and diabetes mellitus were more frequent in obese patients in the OR group. The hyperlipidemia treatment could have played a protective role.26 Moreover, diabetes mellitus is not a recognized risk factor after OR.27 There was a trend to have more patients obese in EVAR group after 2010, this patient had less morbidity (age and chronic kidney disease) than nonobese patients. Therefore, our results do not, unfortunately, help surgeons to identify the type of surgical procedure that might be chosen in obese patients. However, our work does suggest that obesity should not systematically lead to the decision to use EVAR. Surprisingly, the mean operative time in OR was no higher in the obese group, but blood loss was greater. The hospital stay in OR seemed similar to that in EVAR; this is probably because there was a learning curve and until 2009 EVAR was used in high-risk patients,9 who could not be discharged quickly after the intervention. This could be explained because the hospital stay was higher before 2010 in EVAR group unlike OR group. Wound complications were not higher in obese patient. The main limit of our study was the lack of power concerning the impact of obesity on the prognosis. This was probably due the separate analyses in 2 groups, despite the large number of patients studied. It was a monocentric retrospective study. Populations of obese and nonobese patients were heterogen. But we have conducted a multivariable analysis to study the independent impact of obesity compared with known confounding factors.
CONCLUSIONS There was a trend to treat obese patients more and more by EVAR. But the main result of our study
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