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Predictors of renal dysfunction after endovascular and open repair of abdominal aortic aneurysms
From the Society for Clinical Vascular Surgery
Predictors of renal dysfunction after endovascular and open repair of abdominal aortic aneurysms Sara L. Zettervall, MD, MPH, Klaas H. J. Ultee, MD, Peter A. Soden, MD, Sarah E. Deery, MD, Katie E. Shean, MD, Alexander B. Pothof, MD, Mark Wyers, MD, and Marc L. Schermerhorn, MD, Boston, Mass
ABSTRACT Objective: Renal complications after repair of abdominal aortic aneurysms (AAAs) have been associated with increased morbidity and mortality. However, limited data have assessed risk factors for renal complications in the endovascular era. This study aimed to identify predictors of renal complications after endovascular AAA repair (EVAR) and open repair. Methods: Patients who underwent EVAR or open repair of a nonruptured infrarenal AAA between 2011 and 2013 were identified in the National Surgical Quality Improvement Project Targeted Vascular module. Patients on hemodialysis preoperatively were excluded. Renal complications were defined as new postoperative dialysis or creatinine increase >2 mg/dL. Patient demographics, comorbidities, glomerular filtration rate (GFR), operative details, and outcomes were compared using univariate analysis between those with and without renal complications. Multivariable logistic regression was used to identify independent predictors of renal complications. Results: We identified 4503 patients who underwent elective repair of an infrarenal AAA (EVAR: 3869, open repair: 634). Renal complication occurred in 1% of patients after EVAR and in 5% of patients after open repair. There were no differences in comorbidities between patients with and without renal complications. A preoperative GFR <60 mL/min/ 1.73m2 occurred more frequently among patients with renal complications (EVAR: 81% vs 37%, P < .01; open: 60% vs 34%, P < .01). The 30-day mortality was also significantly increased (EVAR: 55% vs 1%, P < .01; open: 30% vs 4%, P < .01). After adjustment, renal complications were strongly associated with 30-day mortality (odds ratio [OR], 38.3; 95% confidence interval [CI], 20.4-71.9). Independent predictors of renal complications included GFR <60 mL/min/1.73m2 (OR, 4.6; 95% CI, 2.4-8.7), open repair (OR, 2.6; 95% CI, 1.3-5.3), transfusion (OR, 6.1; 95% CI, 3.0-12.6), and prolonged operative time (OR, 3.0; 95% CI, 1.6-5.6). Conclusions: Predictors of renal complications include elevated baseline GFR, open approach, transfusion, and prolonged operative time. Given the dramatic increase in mortality associated with renal complications, care should be taken to use renal protective strategies, achieve meticulous hemostasis to limit transfusions, and to use an endovascular approach when technically feasible. (J Vasc Surg 2016;-:1-6.)
Renal complications after surgery are associated with increased mortality, prolonged hospital length of stay, and higher health care costs.1-3 After open repair of abdominal aortic aneurysms (AAA), 30-day and longterm mortality have both been strongly associated with postoperative renal complications.4 Prior work has shown predictors of renal complications after AAA repair From the Division of Vascular and Endovascular Surgery, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School. This work was completed with support from the National Institutes of Health Harvard-Longwood Research Training in Vascular Surgery grant T32-HL007734 to S.L.Z., P.A.S. K.E.S., and S.E.D. Author conflict of interest: M.L.S. is a paid consultant for Endologix, Medtronic, Gore, and Cook. Presented at the Forty-fourth Annual Symposium of the Society for Clinical Vascular Surgery Meeting, Las Vegas Nev, March 12-16, 2016. Correspondence: Marc L. Schermerhorn, MD, 110 Francis St. Ste 5B, Boston, MA 02215 (e-mail: [email protected]).
include preoperative kidney dysfunction and chronic obstructive pulmonary disease.4 Additional operative factors, such as urgency of presentation, suprarenal clamping, and operative time, have also been associated with renal complications.2,4 Despite these findings, previous studies have included predominantly open aneurysm repairs with varying proximal extent of aneurysms and operative urgency. The effects of renal dysfunction on mortality in the endovascular era and the predictors of such complications after endovascular AAA repair (EVAR) remain unclear. Therefore, this study aimed to identify the rate of postoperative renal complications and subsequent mortality associated with this adverse event among patients undergoing EVAR and open repair of intact infrarenal aneurysms in the endovascular era and to identify predictors of renal dysfunction among patients.
The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2016 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jvs.2016.06.113
METHODS Patients. The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) Targeted Vascular Module was used to identify all patients undergoing elective repairs for intact infrarenal 1
2
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Table I. Baseline demographics and comorbidities EVAR No renal complication (n ¼ 3836)
Outcome Age, median (SD) years
75 (8.6)
Open
Renal complication (n ¼ 33)
P value
No renal complication (n ¼ 604)
Renal complication (n ¼ 30)
P value
80 (9.3)
.01
70 (9.3)
69 (10.3)
.46
Male gender, No. (%)
3121 (81)
22 (67)
.03
451 (75)
24 (80)
.51
White race, No. (%)
3318 (87)
27 (82)
.43
484 (80.1)
25 (83)
.67 <.01
GFR <60 mL/min/1.73m , No. (%)
1435 (37)
27 (81)
<.01
203 (34)
18 (60)
Diabetes, No. (%)
616 (16)
6 (18)
.74
693 (16)
8 (13)
.53
COPD, No. (%)
106 (18)
6 (20)
.81
796 (18)
15 (24)
.23
9 (2)
1 (3)
.39
67 (2)
1 (2)
.96
Hypertension, No. (%)
493 (82)
25 (83)
.81
3590 (81)
55 (87)
.20
Smoking, No. (%)
259 (43)
14 (47)
.71
1410 (32)
26 (41)
.11
2
CHF, No. (%)
CHF, Congestive heart failure; COPD, chronic obstructive pulmonary disease; GFR, glomerular filtration rate; SD, standard deviation.
AAAs from 2011 to 2014. The Beth Israel Deaconess Medical Center Institutional Review Board approved this study, and consent was waived owing to the deidentified nature of the NSQIP database. Patients with juxtarenal, pararenal, and suprarenal AAAs were excluded to minimize the effect of clamp time. The analysis also excluded those on dialysis preoperatively (n ¼ 88). The targeted NSQIP is a national clinical registry developed in 2011, which collects patient demographics, operative details, and 30-day outcomes from patients undergoing surgical procedures at > 65 self-selected hospitals. Further information is available at www.facs.org/quality-programs/acs-nsqip. Variables. Patient demographics, age, and comorbid conditions were compared between those with and without renal complications and are listed in Table I. Smoking was defined as current tobacco use. The glomerular filtration rate (GFR) was calculated in accordance with the Modification of Diet in Renal Disease (MDRD) equation, and chronic kidney disease was identified according the Kidney Disease: Improving Global Outcomes (KDIGO) and Acute Kidney Injury Network Clinical Practice Guidelines.5-7 The operative variables compared are listed in Table II and include aneurysm diameter, transfusion, renal revascularization, and lower extremity revascularization, as defined by NSQIP. Transfusion was defined as any transfusion #72 hours of the initial operation. Prolonged operative time was defined as >2 standard deviations from the mean (>180 minutes for EVAR and >360 minutes for open repair). All outcomes measured occurred #30 days of operation. A renal complication was defined as a creatinine increase >2 mg/dL from baseline or new dialysis in the 30-day postoperative period, as defined by NSQIP. A pulmonary complication was defined as pneumonia, failure to wean from mechanical ventilation #48 hours,
reintubation, or pulmonary embolism. Prolonged length of stay was defined as >2 days after EVAR and >7 days after open repair. Statistics. Statistical analyses were performed using SPSS 21.0 software (IBM Corp, Armonk, NY). Univariate analysis was stratified by EVAR or open repair, and patients with and without renal complications were compared using c2 and Fisher exact tests for categoric variables, as appropriate. The Student t-test and MannWhitney U test were used to assess continuous variables, as appropriate. All preoperative variables and outcomes compared had <2% missing data, with the exception of lower extremity revascularization (10.9% missing data). Independent predictors of renal complications, mortality, and prolonged length of stay were established using multivariable logistic regression. Purposeful selection was used to select variables for inclusion.8 This included all variables with P < .1 on univariate analysis and those variables shown to be predictive of the outcome of interest in previous studies. The Hosmer-Lemeshow goodness of fit test was used to evaluate each model. A P value of <.05 was considered significant.
RESULTS We identified 4503 patients, 3869 of whom underwent EVAR and 634 had open repair. Renal complications, as defined by NSQIP, occurred in 33 patients (1%) after EVAR and in 30 patients (5%) after open repair. Dialysis was initiated in 22 patients (0.6%) after EVAR and in 26 patients (4%) after open repair. Baseline characteristics. Among those treated with EVAR, patients with renal complications were older (80 vs 75 years, P ¼ .01), less commonly male (67% vs 81%; P ¼ .03), and more commonly had a GFR <60 mL/min/1.73m2 (81% vs 37%; P < .01). Among
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Table II. Operative characteristics EVAR
Outcomea
No renal complication (n ¼ 3836)
Renal complication (n ¼ 33)
Open
P valueb
No renal complication (n ¼ 604)
Renal complication (n ¼ 30)
<.01
221 (168-285)
374 (220-457)
<.01
.15
5.8 (5.2-6.7)
6.6 (5.8-8.6)
<.01
417 (69)
23 (77)
.38
Operative time, min
132 (103-171)
183 (130-275)
Diameter, cm
5.5 (5.1-6.0)
5.8 (5.1-7.7)
Transfusion
373 (10)
24 (72)
<.01
P valueb
Revascularization Renal
170 (4)
4 (12)
.06
25 (4)
2 (7)
.50
Lower extremity
138 (4)
4 (13)
.04
39 (7)
5 (17)
.04
a
Continuous data are presented as the median (interquartile range) and categoric data as number (%). b Bold values indicate statistical significance (P < .05).
patients undergoing open repair, only GFR <60 mL/min/ 1.73m2 differed between patients with and without renal complications (60% vs 34%; P < .01; Table I). Operative characteristics. Patients with renal complications after EVAR had longer operative times (183 minutes vs 132 minutes; P < .01) and more lower extremity revascularizations (13% vs 4%; P < .01) and transfusions (70% vs 10%; P < .01). There were no significant differences in AAA diameter or proportion of patients undergoing renal revascularization. After open repair, patients with renal complications had longer operative times (374 minutes vs 221 minutes; P < .01), larger AAA diameters (6.6 cm vs 5.8 cm; P < .01), and more lower extremity revascularizations (15% vs 5%; P ¼ .03). There were no differences in transfusions or the proportion with concurrent renal revascularization (Table II). Outcomes. Morbidity and mortality both increased among patients with renal complications. Among EVAR patients, 30-day mortality was 55% in patients with renal complications compared with 1% without renal complications (P < .01). Major complications, including myocardial infarction (21% vs 1%; P < .01), pulmonary complications (49% vs 2%; P < .01), ischemic colitis (15% vs 0.3%; P < .01), and lower extremity ischemia (15% vs 1%; P < .01), were also more common among patients with renal complications. Median hospital stay was 8 days among patients with renal complications and 2 days among those without (P < .01). After open repair, 30-day mortality was 30% among those with renal complications and 4% among those without (P < .01). Similar to EVAR, pulmonary complications (80% vs 13%; P < .01), ischemic colitis (23% vs 2%; P < .01), and lower extremity ischemia (17% vs 2%; P < .01) were increased among patients with renal complications. The median hospital stay was 19 days among patients with renal complications compared with 7 days among patients without (P < .01; Table III).
Multivariable analysis, adjusting for patient demographics, comorbidities, and operative approach, showed renal complications were predictive of 30-day mortality (odds ratio [OR], 38.3; 95% confidence interval [CI], 20.4-71.9) and prolonged length of stay (OR, 8.3; 95% CI, 4.2-16.4). Predictors of renal complications. After multivariable adjustment for only those characteristics available to surgeons preoperatively, GFR <60 mL/min/1.73m2 (OR, 5.7; 95% CI, 3.0-10.6), AAA diameter (OR, 1.1; 95% CI, 1.02-1.2), and open repair (OR, 6.0; 95% CI, 3.5-10.3) were predictive of renal complications. When intraoperative characteristics were added to the same model, GFR <60 mL/min/1.73m2 (OR, 4.6; 95% CI, 2.4-8.7), open repair (OR, 2.6; 95% CI, 1.3-5.3), transfusion (OR, 6.1; 95% CI, 3.0-12.6), and prolonged operative time (OR, 3.0; 95% CI, 1.6-5.6) were independently predictive of renal complications (Table IV).
DISCUSSION This study found that postoperative renal complications, defined as an increase in creatinine of 2.0 mg/dL from baseline or new dialysis, occur in 1% of elective infrarenal EVARs and in 5% of open repairs and are associated with a significant increase in mortality, morbidity, and prolonged length of stay compared with those patients without renal complications. Moreover, a baseline GFR <60 mL/min/1.73m2, open operative approach, transfusion, and prolonged operative time are independently predictive of renal complications. The reported rates of renal complications vary in current literature. Reported rates after open repair have ranged from 5% to 11%.2,4,9 Lower rates of 2% to 7% have been reported in patients after EVAR.9-11 Our study found a rate of renal complications after open repair similar to the 6% reported by Grant et al2 in a study of 2347 consecutive repairs but was lower than other prior studies. This variation was likely because of differences in the study population and the definition of renal
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Table III. Univariate outcomes EVAR
Outcomea
No renal complication (n ¼ 3836)
Renal complication (n ¼ 33)
Open
P valueb
No renal complication (n ¼ 604)
Renal complication (n ¼ 30)
P valueb
30-day mortality
38 (1)
18 (55)
<.01
23 (4)
9 (30)
<.01
Pulmonary complication
73 (2)
16 (49)
<.01
81 (13)
24 (80)
<.01
Ischemic colitis
13 (0.3)
5 (15)
<.01
10 (2)
7 (23)
<.01 <.01
Lower extremity ischemia
45 (1)
5 (15)
<.01
11 (2)
5 (17)
Myocardial infarction
46 (1)
7 (21)
<.01
12 (2)
1 (3)
.47
Reoperation
22 (1)
1 (3)
.18
12 (2)
1 (3)
.47
Hospital stay, days
2 (1-3)
8 (4-20)
<.01
7 (5-9)
19 (12-29)
<.01
a
Categoric data are shown as number (%) and continuous data as median (interquartile range). Bold values are statistically significant (P < .05).
b
dysfunction. Our study evaluated infrarenal aneurysms only, with a renal complication defined by NSQIP as an increase in creatinine of >2.0 mg/dL from baseline or new-onset dialysis. This differs from previous work by Patel et al4 and Ellenberg et al,12 who had a less stringent definition of renal complications, defined as all those with a creatinine increase >0.5 mg/dL, and included all elective open repairs, including those using a suprarenal clamp, which is known to be independently associated with increased renal complications. Fewer studies have directly addressed renal function after EVAR; however, Mehta et al10 reported rates of 3% to 7% after EVAR among patients treated in the first years of EVAR use (1996-2000) and also included physician-made grafts for patients with complex anatomy, both of which likely explain the increased renal complication rate compared with our study. In a more recent study, Saratzis et al13 found a rate of renal complications of 19%. This rate was likely higher than our work and previous studies, owing to their use of the highly sensitive KDIGO definition of renal dysfunction which included an increase in creatinine of >0.3 mg/dL as well as low urine output.13 Given the infrequency of renal complications, large databases are necessary to adequately power studies on acute kidney injury. However, a common definition of renal complications has not been widely used by any major databases, including Vascular Quality Initiative, NSQIP, Medicare, or National Inpatient Sample (NIS), leading to variable reports of such complications. The 2012 KDIGO and Acute Kidney Injury Network guidelines define acute kidney injury as an increase in creatinine of >0.3 mg/dL, a 50% increase in creatinine from baseline, or a reduction in urine output to <0.5 mL/kg per hour for >6 hours, are the most widely used guidelines for acute kidney injury.7,14 However, like many alternative definitions, the utility of this definition is challenged by the difficulty and reliability or urine collection at many institutions and the potential for fluid shifts among
Table IV. Multivariable predictors of renal complications OR
Open repair
2.6
1.3-5.3
<.01
GFR <60 mL/min/1.73m2
4.6
2.4-8.7
<.01
Transfusion
6.1
3.0-12.6
<.01
Prolonged operative time
3.0
1.6-5.6
<.01
Age (decade)
0.9
0.7-1.3
.63
1.0
0.5-1.9
.93
0.7
0.1-5.3
.71
1.4
0.7-2.7
.33
Diabetes
0.9
0.4-2.0
.73
Diameter
1.0
0.9-1.1
.23
Female gender Congestive heart failure COPD
95% CI
P valuea
Predictor
Revascularization Renal
1.4
0.5-3.9
.48
Lower extremity
1.2
0.5-3.0
.73
CI, Confidence interval; COPD, chronic obstructive pulmonary disease; GFR, glomerular filtration rate; OR, odds ratio. a Bold values are statistically significant (P < .05).
surgical patients. Nonetheless, NSQIP and other large databases would be improved by reporting of postoperative creatinine and GFR levels to more uniformly evaluate postoperative renal dysfunction. Increased mortality among patients with renal complications after open AAA repair was also demonstrated in prior work.2,4,13,15,16 Our study found 30-day mortality rates of 30% after open repair and 55% after EVAR among patients with renal complications. These rates are similar to those reported by Grant et al,2 who found a 30-day mortality rate of 35% in their study of 2378 open repairs. However, mortality rates among patients with renal complications vary tremendously in the literature and range from 9% to 58% after open repair. Much of this variation is likely due to differing definitions of renal dysfunction, with lower mortality rates seen in those studies that used the lower cutoff of a 0.5 mg/dL increase from baseline as their definition of a renal complication. Few
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studies have evaluated the mortality rates after EVAR among patients with renal complications, and additional research is warranted to confirm our findings. Saratzis et al5 found a mortality rate of 32% after EVAR; however, their study used more sensitive definition of acute kidney injury, including a significantly lower increase of serum creatinine. Despite differing rates of renal complications, we found similar predictors of this adverse outcome compared with prior work in patients undergoing open repair.2,4,12,16,17 Only one previous study, from Wald et al,16 identified predictors after EVAR and open repair using the NIS and found open repair, chronic kidney disease, and congestive heart failure were associated with postoperative renal complications. However, owing to limitations of the NIS database, the authors were unable to account for operative and anatomic characteristics, including transfusion, operative time, and aneurysm extent.16 In addition, the NIS is considered a suboptimal data set for evaluation of postoperative morbidity because it is an administrative data set that relies on coding, rather than record review, and cannot identify events occurring after discharge. Finally, previous work has shown administrative databases are inferior to the NSQIP and record review in identifying perioperative complications.18,19 After open repair, other authors have identified baseline kidney dysfunction, transfusion, urgency, clamp location, and renal ischemia as other predictors of renal complications. These studies, however, included suprarenal and ruptured aneurysms, which have significantly different risks compared with elective infrarenal aneurysms, and as such, we elected to exclude them for this study.2,4,12,16,17 The results of this study have some important clinical implications. Chronic kidney disease and operative approach are both characteristics known to the surgeon in the preoperative period and should be used for patient education and preoperative risk assessment. Furthermore, given the risk of open repair in those with chronic kidney disease, surgeons should use an EVARfirst approach for patients with suitable anatomy. In addition, in all patients, but particularly those with a GFR <60 mL/min/1.73m2, surgeons should take care to limit the volume of contrast used to avoid further renal deterioration and contrast nephropathy. Transfusion and operative time are characteristics reflective of challenging cases and may not be avoidable; however, given their strong association with renal complications, particular care to minimize blood loss and to ensure complete hemostasis at the closure of the case should be taken. This study has multiple limitations that must be noted. First, it is subject to the generic limitations of a clinical registry, including errors in coding, missing data, and limited variable definitions. Therefore, other confounders, including blood loss, clamp time, neck length,
angulation, and thrombus, may have affected this study and cannot be accounted for. In the current era, open repairs are often more technically challenging owing to poor anatomy for EVAR; however, in this analysis, we excluded those patients with short necks (suprarenal, pararenal, and juxtarenal clamps). As a result the rates of renal dysfunction after open repair may not be reflective of all open AAA repairs. In addition, this study was unable to assess the longterm effects of renal complications. This study was also unable to account for the volume of contrast used; however, contrast volume is often not known in the preoperative period and as such does not assist with preoperative risk stratification. Finally, renal dysfunction was restricted to the VSGNE definition of renal dysfunction and characterized by a large increase in creatinine of >2 mg/dL, which neglects to include patients with less severe renal dysfunction; therefore, the effects of mild kidney injury and the exact cause of dysfunction could not be evaluated.
CONCLUSIONS Predictors of renal complications include elevated baseline GFR, open approach, transfusion, and prolonged operative time. Given the dramatic increase in mortality associated with renal complications, care should be taken to use renal protective strategies, achieve meticulous hemostasis to limit transfusions, and to use an endovascular approach when technically feasible.
AUTHOR CONTRIBUTIONS Conception and design: SZ, KU, PS, MS Analysis and interpretation: SZ, KU, PS, SD, KS, AP, MW, MS Data collection: SZ, MS Writing the article: SZ Critical revision of the article: SZ, KU, PS, SD, KS, AP, MW, MS Final approval of the article: SZ, KU, PS, SD, KS, AP, MW, MS Statistical analysis: SZ, KU, PS, SD, KS, MS Obtained funding: SZ, PS, SD, KS Overall responsibility: MS
REFERENCES 1. Hobson C, Ozrazgat-Baslanti T, Kuxhausen A, Thottakkara P, Efron PA, Moore FA, et al. Cost and mortality associated with postoperative acute kidney injury. Ann Surg 2015;261:1207-14. 2. Grant SW, Grayson AD, Grant MJ, Purkayastha D, McCollum CN. What are the risk factors for renal failure following open elective abdominal aortic aneurysm repair? Eur J Vasc Endovasc Surg 2012;43:182-7. 3. Loef BG, Epema AH, Smilde TD, Henning RH, Ebels T, Navis G, et al. Immediate postoperative renal function deterioration in cardiac surgical patients predicts in-hospital mortality and long-term survival. J Am Soc Nephrol 2005;16:195-200. 4. Patel VI, Lancaster RT, Ergul E, Conrad MF, Bertges D, Schermerhorn M, et al. Postoperative renal dysfunction independently predicts late mortality in patients undergoing aortic reconstruction. J Vasc Surg 2015;62:1405-12.
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5. KDIGO 2012 clinical practice guidelines for the evaluation and management of chronic kidney disease. Kidney Int Suppl 2013;3:1-163. 6. Levey AS, Coresh J, Greene T, Stevens LA, Zhang YL, Hendriksen S, et al. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med 2006;145:247-54. 7. Mehta RL, Kellum JA, Shah SV, Molitoris BA, Ronco C, Warnock DG, et al. Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury. Crit Care 2007;11:R31. 8. Bursac Z, Gauss CH, Williams DK, Hosmer DW. Purposeful selection of variables in logistic regression. Source Code Biol Med 2008;3:1-8. 9. Schermerhorn ML, Buck DB, O’Malley AJ, Curran T, McCallum JC, Darling J, et al. Long-term outcomes of abdominal aortic aneurysm in the Medicare population. N Engl J Med 2015;373:328-38. 10. Mehta M, Byrne J, Darling RC, Paty PS, Roddy SP, Kreienberg PB, et al. Endovascular repair of ruptured infrarenal abdominal aortic aneurysm is associated with lower 30-day mortality and better 5-year survival rates than open surgical repair. J Vasc Surg 2013;57:368-75. 11. Becquemin JP, Pillet JC, Lescalie F, Sapoval M, Goueffic Y, Lermusiaux P, 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;53:1167-73.e1. 12. Ellenberger C, Schweizer A, Diaper J, Kalangos A, Murith N, Katchatourian G, et al. Incidence, risk factors and prognosis
13.
14. 15.
16.
17.
18.
19.
2016
of changes in serum creatinine early after aortic abdominal surgery. Intensive Care Med 2006;32:1808-16. Saratzis A, Melas N, Mahmood A, Sarafidis P. Incidence of acute kidney injury (AKI) after endovascular abdominal aortic aneurysm repair (EVAR) and impact on outcome. Eur J Vasc Endovasc Surg 2015;49:534-40. KDIGO clinical practice guideline for acute kidney injury. Kidney Int Suppl 2012;2:1-138. Olsen PS, Schroeder T, Perko M, Roder OC, Agerskov K, Sorensen S, et al. Renal failure after operation for abdominal aortic aneurysm. Ann Vasc Surg 1990;4:580-3. Wald R, Waikar SS, Liangos O, Pereira BJ, Chertow GM, Jaber BL. Acute renal failure after endovascular vs open repair of abdominal aortic aneurysm. J Vasc Surg 2006;43: 460-6; discussion: 466. Ambler GK, Coughlin PA, Hayes PD, Varty K, Gohel MS, Boyle JR. Incidence and outcomes of severe renal impairment following ruptured abdominal aortic aneurysm repair. Eur J Vasc Endovasc Surg 2015;50:443-9. Bensley RP, Yoshida S, Lo RC, Fokkema M, Hamdan AD, Wyers MC, et al. Accuracy of administrative data versus clinical data to evaluate carotid endarterectomy and carotid stenting. J Vasc Surg 2013;58:412-9. Fokkema M, Hurks R, Curran T, Bensley RP, Hamdan AD, Wyers MC, et al. The impact of the present on admission indicator on the accuracy of administrative data for carotid endarterectomy and stenting. J Vasc Surg 2014;59: 32-8.e1.
Submitted May 6, 2016; accepted Jun 25, 2016.
Predictors of renal dysfunction after endovascular and open repair of abdominal aortic aneurysms Sara L. Zettervall, MD, MPH, Klaas H. J. Ultee, MD, Peter A. Soden, MD, Sarah E. Deery, MD, Katie E. Shean, MD, Alexander B. Pothof, MD, Mark Wyers, MD, and Marc L. Schermerhorn, MD, Boston, Mass
ABSTRACT Objective: Renal complications after repair of abdominal aortic aneurysms (AAAs) have been associated with increased morbidity and mortality. However, limited data have assessed risk factors for renal complications in the endovascular era. This study aimed to identify predictors of renal complications after endovascular AAA repair (EVAR) and open repair. Methods: Patients who underwent EVAR or open repair of a nonruptured infrarenal AAA between 2011 and 2013 were identified in the National Surgical Quality Improvement Project Targeted Vascular module. Patients on hemodialysis preoperatively were excluded. Renal complications were defined as new postoperative dialysis or creatinine increase >2 mg/dL. Patient demographics, comorbidities, glomerular filtration rate (GFR), operative details, and outcomes were compared using univariate analysis between those with and without renal complications. Multivariable logistic regression was used to identify independent predictors of renal complications. Results: We identified 4503 patients who underwent elective repair of an infrarenal AAA (EVAR: 3869, open repair: 634). Renal complication occurred in 1% of patients after EVAR and in 5% of patients after open repair. There were no differences in comorbidities between patients with and without renal complications. A preoperative GFR <60 mL/min/ 1.73m2 occurred more frequently among patients with renal complications (EVAR: 81% vs 37%, P < .01; open: 60% vs 34%, P < .01). The 30-day mortality was also significantly increased (EVAR: 55% vs 1%, P < .01; open: 30% vs 4%, P < .01). After adjustment, renal complications were strongly associated with 30-day mortality (odds ratio [OR], 38.3; 95% confidence interval [CI], 20.4-71.9). Independent predictors of renal complications included GFR <60 mL/min/1.73m2 (OR, 4.6; 95% CI, 2.4-8.7), open repair (OR, 2.6; 95% CI, 1.3-5.3), transfusion (OR, 6.1; 95% CI, 3.0-12.6), and prolonged operative time (OR, 3.0; 95% CI, 1.6-5.6). Conclusions: Predictors of renal complications include elevated baseline GFR, open approach, transfusion, and prolonged operative time. Given the dramatic increase in mortality associated with renal complications, care should be taken to use renal protective strategies, achieve meticulous hemostasis to limit transfusions, and to use an endovascular approach when technically feasible. (J Vasc Surg 2016;-:1-6.)
Renal complications after surgery are associated with increased mortality, prolonged hospital length of stay, and higher health care costs.1-3 After open repair of abdominal aortic aneurysms (AAA), 30-day and longterm mortality have both been strongly associated with postoperative renal complications.4 Prior work has shown predictors of renal complications after AAA repair From the Division of Vascular and Endovascular Surgery, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School. This work was completed with support from the National Institutes of Health Harvard-Longwood Research Training in Vascular Surgery grant T32-HL007734 to S.L.Z., P.A.S. K.E.S., and S.E.D. Author conflict of interest: M.L.S. is a paid consultant for Endologix, Medtronic, Gore, and Cook. Presented at the Forty-fourth Annual Symposium of the Society for Clinical Vascular Surgery Meeting, Las Vegas Nev, March 12-16, 2016. Correspondence: Marc L. Schermerhorn, MD, 110 Francis St. Ste 5B, Boston, MA 02215 (e-mail: [email protected]).
include preoperative kidney dysfunction and chronic obstructive pulmonary disease.4 Additional operative factors, such as urgency of presentation, suprarenal clamping, and operative time, have also been associated with renal complications.2,4 Despite these findings, previous studies have included predominantly open aneurysm repairs with varying proximal extent of aneurysms and operative urgency. The effects of renal dysfunction on mortality in the endovascular era and the predictors of such complications after endovascular AAA repair (EVAR) remain unclear. Therefore, this study aimed to identify the rate of postoperative renal complications and subsequent mortality associated with this adverse event among patients undergoing EVAR and open repair of intact infrarenal aneurysms in the endovascular era and to identify predictors of renal dysfunction among patients.
The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2016 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jvs.2016.06.113
METHODS Patients. The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) Targeted Vascular Module was used to identify all patients undergoing elective repairs for intact infrarenal 1
2
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Table I. Baseline demographics and comorbidities EVAR No renal complication (n ¼ 3836)
Outcome Age, median (SD) years
75 (8.6)
Open
Renal complication (n ¼ 33)
P value
No renal complication (n ¼ 604)
Renal complication (n ¼ 30)
P value
80 (9.3)
.01
70 (9.3)
69 (10.3)
.46
Male gender, No. (%)
3121 (81)
22 (67)
.03
451 (75)
24 (80)
.51
White race, No. (%)
3318 (87)
27 (82)
.43
484 (80.1)
25 (83)
.67 <.01
GFR <60 mL/min/1.73m , No. (%)
1435 (37)
27 (81)
<.01
203 (34)
18 (60)
Diabetes, No. (%)
616 (16)
6 (18)
.74
693 (16)
8 (13)
.53
COPD, No. (%)
106 (18)
6 (20)
.81
796 (18)
15 (24)
.23
9 (2)
1 (3)
.39
67 (2)
1 (2)
.96
Hypertension, No. (%)
493 (82)
25 (83)
.81
3590 (81)
55 (87)
.20
Smoking, No. (%)
259 (43)
14 (47)
.71
1410 (32)
26 (41)
.11
2
CHF, No. (%)
CHF, Congestive heart failure; COPD, chronic obstructive pulmonary disease; GFR, glomerular filtration rate; SD, standard deviation.
AAAs from 2011 to 2014. The Beth Israel Deaconess Medical Center Institutional Review Board approved this study, and consent was waived owing to the deidentified nature of the NSQIP database. Patients with juxtarenal, pararenal, and suprarenal AAAs were excluded to minimize the effect of clamp time. The analysis also excluded those on dialysis preoperatively (n ¼ 88). The targeted NSQIP is a national clinical registry developed in 2011, which collects patient demographics, operative details, and 30-day outcomes from patients undergoing surgical procedures at > 65 self-selected hospitals. Further information is available at www.facs.org/quality-programs/acs-nsqip. Variables. Patient demographics, age, and comorbid conditions were compared between those with and without renal complications and are listed in Table I. Smoking was defined as current tobacco use. The glomerular filtration rate (GFR) was calculated in accordance with the Modification of Diet in Renal Disease (MDRD) equation, and chronic kidney disease was identified according the Kidney Disease: Improving Global Outcomes (KDIGO) and Acute Kidney Injury Network Clinical Practice Guidelines.5-7 The operative variables compared are listed in Table II and include aneurysm diameter, transfusion, renal revascularization, and lower extremity revascularization, as defined by NSQIP. Transfusion was defined as any transfusion #72 hours of the initial operation. Prolonged operative time was defined as >2 standard deviations from the mean (>180 minutes for EVAR and >360 minutes for open repair). All outcomes measured occurred #30 days of operation. A renal complication was defined as a creatinine increase >2 mg/dL from baseline or new dialysis in the 30-day postoperative period, as defined by NSQIP. A pulmonary complication was defined as pneumonia, failure to wean from mechanical ventilation #48 hours,
reintubation, or pulmonary embolism. Prolonged length of stay was defined as >2 days after EVAR and >7 days after open repair. Statistics. Statistical analyses were performed using SPSS 21.0 software (IBM Corp, Armonk, NY). Univariate analysis was stratified by EVAR or open repair, and patients with and without renal complications were compared using c2 and Fisher exact tests for categoric variables, as appropriate. The Student t-test and MannWhitney U test were used to assess continuous variables, as appropriate. All preoperative variables and outcomes compared had <2% missing data, with the exception of lower extremity revascularization (10.9% missing data). Independent predictors of renal complications, mortality, and prolonged length of stay were established using multivariable logistic regression. Purposeful selection was used to select variables for inclusion.8 This included all variables with P < .1 on univariate analysis and those variables shown to be predictive of the outcome of interest in previous studies. The Hosmer-Lemeshow goodness of fit test was used to evaluate each model. A P value of <.05 was considered significant.
RESULTS We identified 4503 patients, 3869 of whom underwent EVAR and 634 had open repair. Renal complications, as defined by NSQIP, occurred in 33 patients (1%) after EVAR and in 30 patients (5%) after open repair. Dialysis was initiated in 22 patients (0.6%) after EVAR and in 26 patients (4%) after open repair. Baseline characteristics. Among those treated with EVAR, patients with renal complications were older (80 vs 75 years, P ¼ .01), less commonly male (67% vs 81%; P ¼ .03), and more commonly had a GFR <60 mL/min/1.73m2 (81% vs 37%; P < .01). Among
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Table II. Operative characteristics EVAR
Outcomea
No renal complication (n ¼ 3836)
Renal complication (n ¼ 33)
Open
P valueb
No renal complication (n ¼ 604)
Renal complication (n ¼ 30)
<.01
221 (168-285)
374 (220-457)
<.01
.15
5.8 (5.2-6.7)
6.6 (5.8-8.6)
<.01
417 (69)
23 (77)
.38
Operative time, min
132 (103-171)
183 (130-275)
Diameter, cm
5.5 (5.1-6.0)
5.8 (5.1-7.7)
Transfusion
373 (10)
24 (72)
<.01
P valueb
Revascularization Renal
170 (4)
4 (12)
.06
25 (4)
2 (7)
.50
Lower extremity
138 (4)
4 (13)
.04
39 (7)
5 (17)
.04
a
Continuous data are presented as the median (interquartile range) and categoric data as number (%). b Bold values indicate statistical significance (P < .05).
patients undergoing open repair, only GFR <60 mL/min/ 1.73m2 differed between patients with and without renal complications (60% vs 34%; P < .01; Table I). Operative characteristics. Patients with renal complications after EVAR had longer operative times (183 minutes vs 132 minutes; P < .01) and more lower extremity revascularizations (13% vs 4%; P < .01) and transfusions (70% vs 10%; P < .01). There were no significant differences in AAA diameter or proportion of patients undergoing renal revascularization. After open repair, patients with renal complications had longer operative times (374 minutes vs 221 minutes; P < .01), larger AAA diameters (6.6 cm vs 5.8 cm; P < .01), and more lower extremity revascularizations (15% vs 5%; P ¼ .03). There were no differences in transfusions or the proportion with concurrent renal revascularization (Table II). Outcomes. Morbidity and mortality both increased among patients with renal complications. Among EVAR patients, 30-day mortality was 55% in patients with renal complications compared with 1% without renal complications (P < .01). Major complications, including myocardial infarction (21% vs 1%; P < .01), pulmonary complications (49% vs 2%; P < .01), ischemic colitis (15% vs 0.3%; P < .01), and lower extremity ischemia (15% vs 1%; P < .01), were also more common among patients with renal complications. Median hospital stay was 8 days among patients with renal complications and 2 days among those without (P < .01). After open repair, 30-day mortality was 30% among those with renal complications and 4% among those without (P < .01). Similar to EVAR, pulmonary complications (80% vs 13%; P < .01), ischemic colitis (23% vs 2%; P < .01), and lower extremity ischemia (17% vs 2%; P < .01) were increased among patients with renal complications. The median hospital stay was 19 days among patients with renal complications compared with 7 days among patients without (P < .01; Table III).
Multivariable analysis, adjusting for patient demographics, comorbidities, and operative approach, showed renal complications were predictive of 30-day mortality (odds ratio [OR], 38.3; 95% confidence interval [CI], 20.4-71.9) and prolonged length of stay (OR, 8.3; 95% CI, 4.2-16.4). Predictors of renal complications. After multivariable adjustment for only those characteristics available to surgeons preoperatively, GFR <60 mL/min/1.73m2 (OR, 5.7; 95% CI, 3.0-10.6), AAA diameter (OR, 1.1; 95% CI, 1.02-1.2), and open repair (OR, 6.0; 95% CI, 3.5-10.3) were predictive of renal complications. When intraoperative characteristics were added to the same model, GFR <60 mL/min/1.73m2 (OR, 4.6; 95% CI, 2.4-8.7), open repair (OR, 2.6; 95% CI, 1.3-5.3), transfusion (OR, 6.1; 95% CI, 3.0-12.6), and prolonged operative time (OR, 3.0; 95% CI, 1.6-5.6) were independently predictive of renal complications (Table IV).
DISCUSSION This study found that postoperative renal complications, defined as an increase in creatinine of 2.0 mg/dL from baseline or new dialysis, occur in 1% of elective infrarenal EVARs and in 5% of open repairs and are associated with a significant increase in mortality, morbidity, and prolonged length of stay compared with those patients without renal complications. Moreover, a baseline GFR <60 mL/min/1.73m2, open operative approach, transfusion, and prolonged operative time are independently predictive of renal complications. The reported rates of renal complications vary in current literature. Reported rates after open repair have ranged from 5% to 11%.2,4,9 Lower rates of 2% to 7% have been reported in patients after EVAR.9-11 Our study found a rate of renal complications after open repair similar to the 6% reported by Grant et al2 in a study of 2347 consecutive repairs but was lower than other prior studies. This variation was likely because of differences in the study population and the definition of renal
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Table III. Univariate outcomes EVAR
Outcomea
No renal complication (n ¼ 3836)
Renal complication (n ¼ 33)
Open
P valueb
No renal complication (n ¼ 604)
Renal complication (n ¼ 30)
P valueb
30-day mortality
38 (1)
18 (55)
<.01
23 (4)
9 (30)
<.01
Pulmonary complication
73 (2)
16 (49)
<.01
81 (13)
24 (80)
<.01
Ischemic colitis
13 (0.3)
5 (15)
<.01
10 (2)
7 (23)
<.01 <.01
Lower extremity ischemia
45 (1)
5 (15)
<.01
11 (2)
5 (17)
Myocardial infarction
46 (1)
7 (21)
<.01
12 (2)
1 (3)
.47
Reoperation
22 (1)
1 (3)
.18
12 (2)
1 (3)
.47
Hospital stay, days
2 (1-3)
8 (4-20)
<.01
7 (5-9)
19 (12-29)
<.01
a
Categoric data are shown as number (%) and continuous data as median (interquartile range). Bold values are statistically significant (P < .05).
b
dysfunction. Our study evaluated infrarenal aneurysms only, with a renal complication defined by NSQIP as an increase in creatinine of >2.0 mg/dL from baseline or new-onset dialysis. This differs from previous work by Patel et al4 and Ellenberg et al,12 who had a less stringent definition of renal complications, defined as all those with a creatinine increase >0.5 mg/dL, and included all elective open repairs, including those using a suprarenal clamp, which is known to be independently associated with increased renal complications. Fewer studies have directly addressed renal function after EVAR; however, Mehta et al10 reported rates of 3% to 7% after EVAR among patients treated in the first years of EVAR use (1996-2000) and also included physician-made grafts for patients with complex anatomy, both of which likely explain the increased renal complication rate compared with our study. In a more recent study, Saratzis et al13 found a rate of renal complications of 19%. This rate was likely higher than our work and previous studies, owing to their use of the highly sensitive KDIGO definition of renal dysfunction which included an increase in creatinine of >0.3 mg/dL as well as low urine output.13 Given the infrequency of renal complications, large databases are necessary to adequately power studies on acute kidney injury. However, a common definition of renal complications has not been widely used by any major databases, including Vascular Quality Initiative, NSQIP, Medicare, or National Inpatient Sample (NIS), leading to variable reports of such complications. The 2012 KDIGO and Acute Kidney Injury Network guidelines define acute kidney injury as an increase in creatinine of >0.3 mg/dL, a 50% increase in creatinine from baseline, or a reduction in urine output to <0.5 mL/kg per hour for >6 hours, are the most widely used guidelines for acute kidney injury.7,14 However, like many alternative definitions, the utility of this definition is challenged by the difficulty and reliability or urine collection at many institutions and the potential for fluid shifts among
Table IV. Multivariable predictors of renal complications OR
Open repair
2.6
1.3-5.3
<.01
GFR <60 mL/min/1.73m2
4.6
2.4-8.7
<.01
Transfusion
6.1
3.0-12.6
<.01
Prolonged operative time
3.0
1.6-5.6
<.01
Age (decade)
0.9
0.7-1.3
.63
1.0
0.5-1.9
.93
0.7
0.1-5.3
.71
1.4
0.7-2.7
.33
Diabetes
0.9
0.4-2.0
.73
Diameter
1.0
0.9-1.1
.23
Female gender Congestive heart failure COPD
95% CI
P valuea
Predictor
Revascularization Renal
1.4
0.5-3.9
.48
Lower extremity
1.2
0.5-3.0
.73
CI, Confidence interval; COPD, chronic obstructive pulmonary disease; GFR, glomerular filtration rate; OR, odds ratio. a Bold values are statistically significant (P < .05).
surgical patients. Nonetheless, NSQIP and other large databases would be improved by reporting of postoperative creatinine and GFR levels to more uniformly evaluate postoperative renal dysfunction. Increased mortality among patients with renal complications after open AAA repair was also demonstrated in prior work.2,4,13,15,16 Our study found 30-day mortality rates of 30% after open repair and 55% after EVAR among patients with renal complications. These rates are similar to those reported by Grant et al,2 who found a 30-day mortality rate of 35% in their study of 2378 open repairs. However, mortality rates among patients with renal complications vary tremendously in the literature and range from 9% to 58% after open repair. Much of this variation is likely due to differing definitions of renal dysfunction, with lower mortality rates seen in those studies that used the lower cutoff of a 0.5 mg/dL increase from baseline as their definition of a renal complication. Few
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studies have evaluated the mortality rates after EVAR among patients with renal complications, and additional research is warranted to confirm our findings. Saratzis et al5 found a mortality rate of 32% after EVAR; however, their study used more sensitive definition of acute kidney injury, including a significantly lower increase of serum creatinine. Despite differing rates of renal complications, we found similar predictors of this adverse outcome compared with prior work in patients undergoing open repair.2,4,12,16,17 Only one previous study, from Wald et al,16 identified predictors after EVAR and open repair using the NIS and found open repair, chronic kidney disease, and congestive heart failure were associated with postoperative renal complications. However, owing to limitations of the NIS database, the authors were unable to account for operative and anatomic characteristics, including transfusion, operative time, and aneurysm extent.16 In addition, the NIS is considered a suboptimal data set for evaluation of postoperative morbidity because it is an administrative data set that relies on coding, rather than record review, and cannot identify events occurring after discharge. Finally, previous work has shown administrative databases are inferior to the NSQIP and record review in identifying perioperative complications.18,19 After open repair, other authors have identified baseline kidney dysfunction, transfusion, urgency, clamp location, and renal ischemia as other predictors of renal complications. These studies, however, included suprarenal and ruptured aneurysms, which have significantly different risks compared with elective infrarenal aneurysms, and as such, we elected to exclude them for this study.2,4,12,16,17 The results of this study have some important clinical implications. Chronic kidney disease and operative approach are both characteristics known to the surgeon in the preoperative period and should be used for patient education and preoperative risk assessment. Furthermore, given the risk of open repair in those with chronic kidney disease, surgeons should use an EVARfirst approach for patients with suitable anatomy. In addition, in all patients, but particularly those with a GFR <60 mL/min/1.73m2, surgeons should take care to limit the volume of contrast used to avoid further renal deterioration and contrast nephropathy. Transfusion and operative time are characteristics reflective of challenging cases and may not be avoidable; however, given their strong association with renal complications, particular care to minimize blood loss and to ensure complete hemostasis at the closure of the case should be taken. This study has multiple limitations that must be noted. First, it is subject to the generic limitations of a clinical registry, including errors in coding, missing data, and limited variable definitions. Therefore, other confounders, including blood loss, clamp time, neck length,
angulation, and thrombus, may have affected this study and cannot be accounted for. In the current era, open repairs are often more technically challenging owing to poor anatomy for EVAR; however, in this analysis, we excluded those patients with short necks (suprarenal, pararenal, and juxtarenal clamps). As a result the rates of renal dysfunction after open repair may not be reflective of all open AAA repairs. In addition, this study was unable to assess the longterm effects of renal complications. This study was also unable to account for the volume of contrast used; however, contrast volume is often not known in the preoperative period and as such does not assist with preoperative risk stratification. Finally, renal dysfunction was restricted to the VSGNE definition of renal dysfunction and characterized by a large increase in creatinine of >2 mg/dL, which neglects to include patients with less severe renal dysfunction; therefore, the effects of mild kidney injury and the exact cause of dysfunction could not be evaluated.
CONCLUSIONS Predictors of renal complications include elevated baseline GFR, open approach, transfusion, and prolonged operative time. Given the dramatic increase in mortality associated with renal complications, care should be taken to use renal protective strategies, achieve meticulous hemostasis to limit transfusions, and to use an endovascular approach when technically feasible.
AUTHOR CONTRIBUTIONS Conception and design: SZ, KU, PS, MS Analysis and interpretation: SZ, KU, PS, SD, KS, AP, MW, MS Data collection: SZ, MS Writing the article: SZ Critical revision of the article: SZ, KU, PS, SD, KS, AP, MW, MS Final approval of the article: SZ, KU, PS, SD, KS, AP, MW, MS Statistical analysis: SZ, KU, PS, SD, KS, MS Obtained funding: SZ, PS, SD, KS Overall responsibility: MS
REFERENCES 1. Hobson C, Ozrazgat-Baslanti T, Kuxhausen A, Thottakkara P, Efron PA, Moore FA, et al. Cost and mortality associated with postoperative acute kidney injury. Ann Surg 2015;261:1207-14. 2. Grant SW, Grayson AD, Grant MJ, Purkayastha D, McCollum CN. What are the risk factors for renal failure following open elective abdominal aortic aneurysm repair? Eur J Vasc Endovasc Surg 2012;43:182-7. 3. Loef BG, Epema AH, Smilde TD, Henning RH, Ebels T, Navis G, et al. Immediate postoperative renal function deterioration in cardiac surgical patients predicts in-hospital mortality and long-term survival. J Am Soc Nephrol 2005;16:195-200. 4. Patel VI, Lancaster RT, Ergul E, Conrad MF, Bertges D, Schermerhorn M, et al. Postoperative renal dysfunction independently predicts late mortality in patients undergoing aortic reconstruction. J Vasc Surg 2015;62:1405-12.
6
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5. KDIGO 2012 clinical practice guidelines for the evaluation and management of chronic kidney disease. Kidney Int Suppl 2013;3:1-163. 6. Levey AS, Coresh J, Greene T, Stevens LA, Zhang YL, Hendriksen S, et al. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med 2006;145:247-54. 7. Mehta RL, Kellum JA, Shah SV, Molitoris BA, Ronco C, Warnock DG, et al. Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury. Crit Care 2007;11:R31. 8. Bursac Z, Gauss CH, Williams DK, Hosmer DW. Purposeful selection of variables in logistic regression. Source Code Biol Med 2008;3:1-8. 9. Schermerhorn ML, Buck DB, O’Malley AJ, Curran T, McCallum JC, Darling J, et al. Long-term outcomes of abdominal aortic aneurysm in the Medicare population. N Engl J Med 2015;373:328-38. 10. Mehta M, Byrne J, Darling RC, Paty PS, Roddy SP, Kreienberg PB, et al. Endovascular repair of ruptured infrarenal abdominal aortic aneurysm is associated with lower 30-day mortality and better 5-year survival rates than open surgical repair. J Vasc Surg 2013;57:368-75. 11. Becquemin JP, Pillet JC, Lescalie F, Sapoval M, Goueffic Y, Lermusiaux P, 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;53:1167-73.e1. 12. Ellenberger C, Schweizer A, Diaper J, Kalangos A, Murith N, Katchatourian G, et al. Incidence, risk factors and prognosis
13.
14. 15.
16.
17.
18.
19.
2016
of changes in serum creatinine early after aortic abdominal surgery. Intensive Care Med 2006;32:1808-16. Saratzis A, Melas N, Mahmood A, Sarafidis P. Incidence of acute kidney injury (AKI) after endovascular abdominal aortic aneurysm repair (EVAR) and impact on outcome. Eur J Vasc Endovasc Surg 2015;49:534-40. KDIGO clinical practice guideline for acute kidney injury. Kidney Int Suppl 2012;2:1-138. Olsen PS, Schroeder T, Perko M, Roder OC, Agerskov K, Sorensen S, et al. Renal failure after operation for abdominal aortic aneurysm. Ann Vasc Surg 1990;4:580-3. Wald R, Waikar SS, Liangos O, Pereira BJ, Chertow GM, Jaber BL. Acute renal failure after endovascular vs open repair of abdominal aortic aneurysm. J Vasc Surg 2006;43: 460-6; discussion: 466. Ambler GK, Coughlin PA, Hayes PD, Varty K, Gohel MS, Boyle JR. Incidence and outcomes of severe renal impairment following ruptured abdominal aortic aneurysm repair. Eur J Vasc Endovasc Surg 2015;50:443-9. Bensley RP, Yoshida S, Lo RC, Fokkema M, Hamdan AD, Wyers MC, et al. Accuracy of administrative data versus clinical data to evaluate carotid endarterectomy and carotid stenting. J Vasc Surg 2013;58:412-9. Fokkema M, Hurks R, Curran T, Bensley RP, Hamdan AD, Wyers MC, et al. The impact of the present on admission indicator on the accuracy of administrative data for carotid endarterectomy and stenting. J Vasc Surg 2014;59: 32-8.e1.
Submitted May 6, 2016; accepted Jun 25, 2016.