A comparison of renal function between open and endovascular aneurysm repair in patients with baseline chronic renal insufficiency

Chronic kidney disease impacts outcomes after abdominal aortic aneurysm repair

OBJECTIVE

Chronic kidney disease (CKD) and end-stage renal disease are traditionally associated with worse outcomes after endovascular and open repair of abdominal aortic aneurysm (AAA). This study stratifies outcomes of AAA repair by approach, CKD severity, and dialysis dependence.

METHODS

All patients undergoing elective infrarenal open aneurysm repair (OAR) and endovascular aortic repair (EVAR) with preoperative renal function data captured by the Vascular Quality Initiative between January 2003 and September 2020 were analyzed. Patients were stratified by CKD class as follows: CKD stages 1 and 2, CKD stage 3a, CKD stage 3b, CKD stages 4 and 5, and dialysis. Primary outcomes were perioperative and 1-year mortality. Predictors of survival were identified by Cox multivariate regression models.

RESULTS

In total, 53,867 elective AAA repairs were identified: 5396 (10%) OARs and 48,471 (90%) EVARs. Most patients were White (90%) and male (81%), with a mean age of 73 ± 9 years. Patients who underwent EVAR were older and had more comorbidities. The use of elective EVAR for AAA increased from 52% in 2003 to 91% in 2020 (P < .001). The OAR cohort had more perioperative complications and short-term mortality. The CKD 1 and 2 group had the highest 1-year survival compared with the other groups after both OAR and EVAR. On Cox regression analysis, after EVAR, compared with CKD 1 and 2, worsening CKD stage (CKD 3a: hazard ratio [HR], 1.25; 95% confidence interval [CI], 0.93-1.68; P = .13; CKD 3b: HR, 1.74; 95% CI, 1.23-2.45; P < .050; CKD 4-5: HR, 3.23; 95% CI, 2.13-4.88; P < .001), and dialysis (HR, 4.48; 95% CI, 1.90-10.6; P < .001) were independently associated with worse 1-year survival rates. After OAR, compared with CKD 1 and 2, worsening CKD stage (CKD 3a: HR, 1.08; 95% CI, 0.96-1.20; P = .20; CKD 3b: HR, 1.60; 95% CI, 1.41-1.81; P < .001; CKD 4-5: HR, 2.85; 95% CI, 2.39-3.41; P < .001), and dialysis (HR, 3.79; 95% CI, 3.01-4.76; P < .001) were independently associated with worse 1-year survival rates.

CONCLUSIONS

Regardless of the treatment approach, CKD severity is an important predictor of perioperative and 1-year mortality rates after infrarenal AAA repair and may reflect the natural history of CKD. Open repair is associated with high perioperative mortality risk in patients with CKD stages 4 and 5, as well as end-stage renal disease. Individualization of patient decision-making is especially important in patients with a glomerular filtration rate of less than 45 and perhaps consideration should be given to raising the threshold for elective AAA repair in these patients. Further studies focusing on appropriate size threshold for repair in these patients may be warranted.

The effect of suprarenal graft fixation during EVAR on short- and long-term renal function

OBJECTIVE

The effect of suprarenal fixation (SR) compared to infrarenal fixation (IR) on renal function during endovascular aneurysm repair (EVAR) remains controversial. This study aims to compare the renal outcomes between fixation types in short- and long-term follow-up.

METHODS

Patients undergoing EVAR for infrarenal abdominal aortic aneurysm between 2005 and 2013 were included. Estimated glomerular filtration rate (eGFR) was measured at baseline and during a follow-up of 5 years. A decline in renal function was defined as a ≥ 20% decrease in eGFR. Changes in eGFR were compared between SR and IR groups at 1-7 days, 30 days, and 1-5 years postoperatively. Preoperative renal insufficiency was defined as eGFR < 60mL/min/1.73m², and those patients were included in the subanalyses.

RESULTS

A total of 358 patients were included. Among these, 267 (74.6%) had SR and 91 (25.4%) had IR fixation. A decline in renal function occurred more commonly after SR than after IR in 1-7 days postoperatively (p = .009), but no difference was noticed at 30 days and 1-5 years. Regardless of the fixation method, renal function steadily decreased steadily over time after EVAR (estimate -3.13 per a year, 95% confidence interval -3.40- -2.85, p < .001). Patients with pre-existing renal insufficiency were included in subgroup analyses, and those with SR were more often found to have a decline in eGFR 5 years postoperatively than their counterparts with IR (59.5% vs 20.0%, p = .036).

CONCLUSION

An immediate postoperative decline in renal function was seen more often after SR fixation than IR fixation but this difference was transient. SR fixation is a safe method for patients with normal renal function. Long-term results seems to favor IR over SR in patients with pre-existing renal insufficiency.

Time-to-Event Analysis of the Impact of Endovascular Aortic Aneurysm Repair on Chronic Renal Decline

BACKGROUND

Although randomized studies have revealed the long-term outcomes of the endovascular repair (ER) of abdominal aortic aneurysm (AAA) compared to open repair (OR), there is controversy surrounding chronic renal decline (CRD) after ER. This study reviewed our propensity-matched cohorts of ER and OR to compare CRD rates using a time-to-event analysis. The ER groups undergoing suprarenal (SR) or infrarenal (IR) proximal fixation were also compared with the OR group.

METHODS

This retrospective review of infrarenal AAA repair was conducted from June 2007-December 2017. Patients with ≥1 year of follow-up were included. Cases of supra/pararenal AAAs, infectious AAAs, rupture, or severe chronic kidney disease (CKD) (estimated glomerular filtration rate (eGFR) <15 mL/min/1.73 m² or dependence on renal replacement therapy) were excluded. CRD was defined as eGFR decline of >20% or de novo hemodialysis during follow-up. Patients treated with ER (ER group) and OR (OR group) were propensity-score matched for age, sex, comorbidities, ejection fraction, respiratory function, and baseline eGFR. Kaplan-Meier analysis compared the freedom from CRD rates of the matched cohorts (mER and mOR groups). Patients treated with SR and IR fixation devices (SR and IR groups) were also separately matched to the OR group, followed by analysis.

RESULTS

In total, 1087 patients underwent elective AAA repair. Among them, 944 (512 ER and 432 OR) were enrolled. The ER group was older than the OR group (median age 79 vs 71; P<0.001). The ER group had significantly lower baseline eGFR and more comorbidities than the OR group. Among 187 propensity-score matched pairs (187 mER and 187 mOS patients), background characteristics, including age and baseline eGFR, were comparable, but median renal function follow-up was significantly longer in the mER group than in the mOR group (48 vs 26 months; P<0.001). CRD was observed in 57 patients in the mER group and 30 patients in the mOR group. Kaplan-Meier analysis of the freedom from CRD showed no significant difference between the matched groups (P=0.268); however, in the later follow-up of >4 years, CRD was more common in the mER group. The matched analyses between the OR group and specific fixation groups, comprising 102 OR-SR and 73 OR-IR pairs, demonstrated no significant differences in CRD.

CONCLUSIONS

Compared to OR, there was no significant impact of ER on CRD at up to 4 years, supporting the safety of ER in terms of the mid-term renal outcome of our present clinical practice.

The effect of Endovascular Aneurysm Repair on Renal Function in Patients Treated for Abdominal Aortic Aneurysm

Aim:

The effect of endovascular aneurysm repair in patients treated for abdominal aortic aneurysm has not been clearly defined. The objective of the present article was to provide a contemporary literature review and perform an analysis to determine the effect of EVAR on renal function in the early post-operative period and during follow-up.

Methods:

A systematic review of the literature was undertaken to identify all studies reporting the effect of EVAR on renal function. Outcome data were pooled and combined overall effect sizes were calculated using fixed or random-effects models.

Results:

Thirty-two studies reporting on 24846 patients were included. Acute renal failure after EVAR occurred with an estimated frequency of 9% (95%CI: 5-16%; I2=97%). Median follow-up period was 19.5 months (range 1-60 months). The estimated frequency of chronic renal failure during follow-up was 7% (95%CI: 3-17%; I2=98%). Hemodialysis was required in 2% (1-3%; I2=97%) of the cases.

Conclusion:

High-level evidence demonstrating the effect of EVAR on the incidence of acute and chronic renal failure is lacking. Based on the current available data, nearly 10% of patients undergoing EVAR for AAA have an increased risk for renal dysfunction after the procedure. Whether this deterioration may lead to a worse outcome has not been adequately proved.

Renal function after abdominal aortic aneurysm repair in patients with baseline chronic renal insufficiency: open vs. endovascular repair

BACKGROUND

The aim of this study is to analyze renal function impairment (RFI) after abdominal aortic aneurysm (AAA) repair in patients with preoperative chronic kidney disease (CKD).

METHODS

Retrospective cohort study of patients with CKD undergoing elective AAA repair between 2008-2015, dividing the sample into two groups: open repair (OR) and endovascular repair (EVAR). The primary outcome was RFI defined by the RIFLE scale, studying Risk (1.5-fold increase in Cr or GFR decline >25% compared to baseline) and kidney injury (doubling of Cr or GFR decline >50%).

RESULTS

Seventy-five patients (OR=29, EVAR=46). Baseline characteristics for OR and EVAR were similar except for age (70.4 vs. 77.2 years; P<0.001), coronary artery disease (31% vs. 56.5%; P=0.04), neck length (12.3 vs. 22.7 mm; P=0.001) and baseline GFR (40.6 vs. 36.9 mL/min; P=0.03). There were no inter-group differences in postoperative RFI: Risk of RFI 13.8% OR vs. 13% EVAR and kidney Injury 6.9% vs. 0% (P=0.19). There were also no differences in RFI at one year. Comparing GFR and Cr after surgery and at 12 months to baseline values, the OR group presented a significant postoperative decline in GFR compared to EVAR group (-3.8% vs. 11.1%; P=0.03), which had recovered at one-year follow-up (16.6% vs. 9.5%; P=0.43), while EVAR group presented with a tendency toward increased Cr during follow-up (-9.2% vs. 2.2%; P=0.08). Multivariate analysis did not identify independent RFI prognostic factors.

CONCLUSIONS

Both techniques can be used safely in patients with CKD and baseline CKD is not a limiting factor for either technique. RFI is rare and transient in both groups.

Theoretical mechanism of temporary renal function improvement after abdominal aortic aneurysm surgery: Applications for clinical imaging and laboratory data

We evaluated the effects of changes in blood flow due to abdominal aortic aneurysm (AAA) surgery by using a simple zero-dimension model and applied theoretical values to clinical data.The zero-dimension electronic circuit model and diagram of blood flow distribution were created by setting the resistance of the aorta, bilateral iliac arteries, renal arteries, and aneurysm. Resistance of the aneurysm and resistance of the aorta before surgery were compared with that of the aorta after surgery. We set the radius length of each anatomical parameter to calculate theoretical values.Renal flow increased 13.4% after surgery. Next, we analyzed contrast-enhanced computed tomography data of 59 patients who underwent AAA surgery. A total of 19 patients were treated with a Y graft and 7 patients were treated with a straight graft during open surgery. However, 33 patients were treated with a bifurcated stent graft. A significant linear relationship between the increased estimated glomerular filtration rate (eGFR) ratio and the decreased aneurysm ratio was found only for the straight graft group.Using a circuit model, renal blood flow theoretically increased after AAA surgery. Clinically, there was a correlation between volume regression and eGFR improvement only in the limited AAA group.

Prospective comparison of dual-energy CT aortography using 70% reduced iodine dose versus single-energy CT aortography using standard iodine dose in the same patient

PURPOSE

To compare dual-energy computed tomography (DECT) aortography using a 70% reduced iodine dose to single-energy CT (SECT) aortography using a standard iodine dose in the same patient.

METHODS

Twenty-one patients with a prior SECT aortography using standard iodine dose had DECT aortography using 70% reduced iodine dose. Section 120 kVp images were compared to DECT images reconstructed at both 50 and 77 keV. Reviewers measured image noise and attenuation in the aorta at eight locations from proximal to distal and subjectively scored vascular enhancement on a four-point scale. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The volume CT dose index (CTDI_vol) for each exam was recorded.

RESULTS

Mean iodine dose was 50 g for SECT and 15 g for DECT (70% reduction). Mean aortic attenuation was similar for section 120 kVp (350 ± 67 HU) and DECT 50 keV (338 ± 57 HU, p = 0.547) but was lower at 77 keV (152 ± 23 HU). Measured image noise was greatest at 50 keV (12 ± 5 HU) and was lowest at 77 keV (7 ± 2 HU, p > 0.001). There was no difference in SNR or CNR between 120 kVp and 50 keV (p > 0.05). Mean subjective vascular enhancement scores for SECT were between good and excellent (3.33-3.69), and for DECT at 50 keV were between moderate and good (2.54-2.93, p < 0.0001). CTDI_vol was 13.6 mGy for SECT and 13.1 mGy for DECT (p = 0.637).

CONCLUSION

70% Reduced iodine DECT aortography may result in similar aortic attenuation, CNR, SNR, and lower although acceptable subjective image scores when compared to standard iodine SECT aortography in the same patient.

Progression to stage 3 and 4 chronic kidney disease and risk factor stratification following endovascular aortic aneurysm repair

Background

Risk of progression to various stages of chronic kidney disease (CKD) after endovascular aortic aneurysm repair (EVAR) is unknown. This study estimates progression rates to stage 3 and 4 CKD after EVAR and identifies potential predictors for progression.

Methods

EVAR cases (2006–2012) were retrospectively reviewed. Freedom of progression to CKD was estimated using Kaplan–Meier analysis, and predictors for progression were identified using Cox proportional hazards model.

Results

Two hundred and twelve consecutive patients at a single academic institution underwent EVAR for infrarenal aneurysms. Estimated freedom from progression to stage 3 CKD was 80%, 76%, and 63% at 6, 12, and 18 months, respectively, and for stage 4, 97%, 96%, and 93% at 6, 12, and 18 months, respectively. Stage 3 CKD predictors of progression included age (odds ratio (OR): 1.106, p = 0.001), diabetes (OR: 3.052, p = 0.04), perioperative use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers (OR: 3.249, p = 0.02), and operative blood loss (OR: 1.002, p < 0.01). Stage 4 predictors included preoperative hemoglobin (OR: 0.473, p = 0.04) and baseline renal function (OR: 0.928, p = 0.001). Intraoperative contrast administration did not impact CKD development.

Conclusions

Progression to stage 3 CKD after EVAR occurs more frequently and at a higher rate compared with progression to stage 4. Different risk factors are associated with progression to each of those stages of CKD.

Prospective Comparison of Reduced-Iodine-Dose Virtual Monochromatic Imaging Dataset From Dual-Energy CT Angiography With Standard-Iodine-Dose Single-Energy CT Angiography for Abdominal Aortic Aneurysm

OBJECTIVE

The purpose of this study was to compare the image quality of reduced-iodine-dose single-source dual-energy CT angiography (CTA) with that of standard-iodine-dose single-energy CTA in examinations of patients with abdominal aortic aneurysm and to assess the effect of the concentration of iodinated contrast medium on intravascular enhancement and image quality of reduced-iodine-dose CTA.

SUBJECTS AND METHODS

In a prospective randomized clinical trial, 66 consecutively registered patients with abdominal aortic aneurysm who had previously undergone single-energy CTA (30-37 g I) underwent follow-up CTA at a reduced dose (21-27 g I) of iodinated contrast medium of either 270 mg I/mL (n = 33) or 320 mg I/mL (n = 33). Two readers independently evaluated virtual monochromatic imaging datasets (40-140 keV) and single-energy CTA images for image quality and noise and their preference for optimal energy virtual monochromatic imaging dataset. A value of p < 0.05 was considered statistically significant.

RESULTS

All 66 dual-energy CTA examinations were rated diagnostic with mean image quality and image noise scores of 4.8 and 4.5 for reader 1 and 3.8 and 3.4 for reader 2 compared with single-energy CTA results of 4.5 and 4.2 for reader 1 and 4.5 and 4.1 for reader 2. Low-energy virtual monochromatic images (40-60 keV) from reduced-iodine-dose (28%) dual-energy CTA had significantly higher intravascular aortic attenuation (26-185%) and contrast-to-noise ratio (CNR) (20-25%) than standard-iodine-dose single-energy CTA images (p < 0.0001). No significant difference was found between patients who received 270 and those who received 320 mg I/mL with respect to intravascular aortic attenuation (p = 0.6331) or CNR (p = 0.9775).

CONCLUSION

Low-energy virtual monochromatic imaging datasets from reduced-iodine (24 g I) single-source dual-energy CTA of the abdomen provide up to 185% higher attenuation and 25% higher CNR than standard-iodine-dose (33.3 g I) single-energy CTA while offering a wide range of energy settings irrespective of the concentration of IV contrast medium used.

Risk factors for early renal dysfunction following endovascular aortic aneurysm repair and its effect on the postoperative outcome

PURPOSE

Renal insufficiency is associated with increased morbidity and death after endovascular aortic aneurysm repair (EVAR). However, the effect of postoperative acute kidney dysfunction on patient outcome has not been fully determined. This study aimed to determine the risk factors of early postoperative renal function decline using chronic kidney disease (CKD) staging and its effect on the clinical outcome.

METHODS

A retrospective analysis was performed on a prospectively maintained EVAR database. Pre- and postoperative CKD stages were determined for all patients according to the estimated glomerular filtration rate values.

RESULTS

We identified 135 patients who were treated with elective EVAR. CKD stage decline was observed in 25 (19 %) of the patients. Freedom from aneurysm-related death was significantly lower in patients with postoperative CKD progression compared with those with unchanged CKD stage. A shaggy aorta without oral beta-blocker administration and higher preoperative serum creatinine levels (>1.4 mg/dL) were found to be independent predictors of an early postoperative CKD stage decline.

CONCLUSIONS

Patients with postoperative CKD progression have an increased frequency of aneurysm-related death. The presence of a shaggy aorta, absence of oral beta-blocker administration and an increased preoperative creatinine level are independent predictors of early postoperative CKD progression.

Diagnostic imaging methods applied in long-term surveillance after EVAR. Will computed tomography angiography be replaced by other methods?

Endovascular implantation of a stent graft in the abdominal aorta (endovascular aneurysm repair – EVAR) is a widely accepted alternative to open surgery in treatment of abdominal aortic aneurysms. Although EVAR is connected with a significant reduction in the risk of peri- and post-operative complications, it does not eliminate them totally. Long-term surveillance of post-EVAR patients is aimed at early detection of and fast reaction to a group of complications called endovascular leaks. Currently, the gold standard in leak diagnostics is computed tomography angiography (CTA). The other methods are ultrasonography, magnetic resonance (MR) angiography, intra-aneurysm sac pressure measurement, X-ray, and digital subtraction angiography (DSA). Despite many analyses based on long-term research, emphasising the high value and competitiveness of less invasive tests such as US or X-ray compared to CTA, it is still difficult for them to win the trust and acceptance of clinicians. The persisting view is that computed tomography is the test that finally resolves any inaccuracies. Consequently, a patient with a number of concurrent diseases is subject to absurdly high radiation exposure and effects of a radiocontrast agent within a short time. It is therefore logical to acknowledge that the EVAR-related risk is catching up with the open surgery risk, while the endovascular procedure is much more costly. Nevertheless, the status of CTA as the gold standard ultimately seems to be unthreatened. This paper presents a description of the diagnostic imaging tests that make it possible to detect any vascular leaks and to develop strategies for therapeutic processes.

Clinical usefulness of urinary liver-type fatty-acid-binding protein as a perioperative marker of acute kidney injury in patients undergoing endovascular or open-abdominal aortic aneurysm repair

Purpose

Acute kidney injury (AKI) is common after cardiovascular surgery and is usually diagnosed on the basis of the serum creatinine (SCr) level and urinary output. However, SCr is of low sensitivity in patients with poor renal function. Because urinary liver-type fatty-acid-binding protein (L-FABP) reflects renal tubular injury, we evaluated whether perioperative changes in urinary L-FABP predict AKI in the context of abdominal aortic repair.

Methods

Study participants were 95 patients who underwent endovascular abdominal aortic aneurysm repair (EVAR) and 42 who underwent open repair. We obtained urine samples before surgery, after anesthesia induction, upon stent placement, before aortic cross-clamping (AXC), 1 and 2 h after AXC, at the end of surgery, 4 h after surgery, and on postoperative days (PODs) 1, 2, and 3, for measurement of L-FABP. We obtained serum samples before surgery, immediately after surgery, and on PODs 1, 2, and 3, for measurement of SCr. We also plotted receiver-operating characteristic (ROC) curves to identify cutoff laboratory values for predicting the onset of AKI.

Results

With EVAR, urinary L-FABP was significantly increased 4 h after the procedure (P = 0.014). With open repair, urinary L-FABP increased significantly to its maximum by 2 h after AXC (P = 0.007). With AKI, SCr significantly increased (P < 0.001, P = 0.001) by POD 2. ROC analysis showed urinary L-FABP to be more sensitive than SCr for early detection of AKI.

Conclusion

Urinary L-FABP appears to be a sensitive biomarker of AKI in patients undergoing abdominal aortic repair.

A systematic review and meta-analysis indicates underreporting of renal dysfunction following endovascular aneurysm repair

Deterioration in renal function has been described after endovascular repair of abdominal aortic aneurysms (EVRs). The etiology is multifactorial and represents an important therapeutic target. A need exists to quantitatively summarize incidence and severity of renal dysfunction after EVR to allow better-informed attempts to preserve renal function and improve life expectancy. Here a systematic search was performed using Medline and Embase for renal function after EVR applying PRISMA statements. Univariate and multivariate random-effects meta-analyses were performed to estimate pooled postoperative changes in serum creatinine and creatinine clearance at four time points after EVR. Clinically relevant deterioration in renal function was also estimated at 1 year or more after EVR. Pooled probability of clinically relevant deterioration in renal function at 1 year or more was 18% (95% confidence interval of 14-23%, I2 of 82.5%). Serum creatinine increased after EVR by 0.05 mg/dl at 30 days/1 month, 0.09 mg/dl at 1 month to 1 year, and 0.11 mg/dl at 1 year or more (all significant). Creatinine clearance decreased after EVR by 5.65 ml/min at 1 month-1 year and by 6.58 ml/min at 1 year or more (both significant). Thus, renal dysfunction after EVR is common and merits attention.

Risk factors and impact of proximal fixation on acute and chronic renal dysfunction after endovascular aortic aneurysm repair using glomerular filtration rate criteria

BACKGROUND

The incidence of renal impairment relevant to proximal fixation of aortic endograft devices remains unclear.

METHODS

Retrospective cohort of 208 consecutive patients that underwent EVAR from 2006 to 2011. Estimated glomerular filtration rate (eGFR) was based on MDRD study equation. Acute kidney injury (AKI) and chronic kidney disease (CKD) were classified with ADIQ/RIFLE criteria and National Kidney Foundation criteria, respectively. Kaplan-Meier curve was applied to evaluate progression to CKD. Multivariate regression model was fit to identify predictors for developing AKI and CKD.

RESULTS

Suprarenal fixation group (SF) included 110 patients and infrarenal fixation group (IF) included 98 patients. Both groups had similar demographics, baseline eGFR, and renal-protection protocols. There was a trend for decreased use of contrast in IF group (median: 93.5 vs. 103 cc, P = 0.07). AKI occurred in 15% of patients in SF group and 19% of patients in IF group (RR: 1.24, P = 0.47). The freedom from progression to stage 3 or 4 CKD in the SF group was 0.76, 0.72, and 0.49 at 6, 12, and 18 months, respectively, while for IF group was 0.8, 0.73, and 0.68, respectively (P = 0.4). Increasing age (P = 0.07), lengthy procedures (P < 0.001), and baseline renal dysfunction (P < 0.001) were significant predictors for developing CKD. Contrast volume (P < 0.001) and ace-inhibitors (P = 0.07) were predictors for AKI.

CONCLUSION

Proximal fixation type has no significant effect on both acute and chronic renal function. Identification of modifiable perioperative risk factors may be used to improve renal function outcomes.

The impact of using informative priors in a Bayesian cost-effectiveness analysis: an application of endovascular versus open surgical repair for abdominal aortic aneurysms in high-risk patients

BACKGROUND

Bayesian methods have been proposed as a way of synthesizing all available evidence to inform decision making. However, few practical applications of the use of Bayesian methods for combining patient-level data (i.e., trial) with additional evidence (e.g., literature) exist in the cost-effectiveness literature. The objective of this study was to compare a Bayesian cost-effectiveness analysis using informative priors to a standard non-Bayesian nonparametric method to assess the impact of incorporating additional information into a cost-effectiveness analysis.

METHODS

Patient-level data from a previously published nonrandomized study were analyzed using traditional nonparametric bootstrap techniques and bivariate normal Bayesian models with vague and informative priors. Two different types of informative priors were considered to reflect different valuations of the additional evidence relative to the patient-level data (i.e., "face value" and "skeptical"). The impact of using different distributions and valuations was assessed in a sensitivity analysis. Models were compared in terms of incremental net monetary benefit (INMB) and cost-effectiveness acceptability frontiers (CEAFs).

RESULTS

The bootstrapping and Bayesian analyses using vague priors provided similar results. The most pronounced impact of incorporating the informative priors was the increase in estimated life years in the control arm relative to what was observed in the patient-level data alone. Consequently, the incremental difference in life years originally observed in the patient-level data was reduced, and the INMB and CEAF changed accordingly.

CONCLUSIONS

The results of this study demonstrate the potential impact and importance of incorporating additional information into an analysis of patient-level data, suggesting this could alter decisions as to whether a treatment should be adopted and whether more information should be acquired.

Clinical Results of Endovascular Abdominal Aortic Aneurysm Repair in Patients with Renal Insufficiency without Hemodialysis

OBJECTIVE

Chronic renal insufficiency may be a relative contraindication to endovascular aneurysm repair (EVAR) for the use of contrast enhanced mediums. It is thought that more contrast enhanced media are needed in patients who are not anatomically suitable for EVAR, because of procedural difficulties. We reviewed a 2 year EVAR experience at our institution to determine whether the procedure and use of contrast enhanced mediums has any deleterious effect on renal function in patients with pre-existing chronic renal insufficiency.

MATERIALS AND METHODS

EVAR was performed in 46 patients with pre-existing chronic renal insufficiency without hemodialysis. Patients were retrospectively assigned to two groups on the basis of their preoperative creatinine clearance levels. Furthermore, patients were assigned to two other groups on the basis of anatomical suitability for EVAR. The absolute change in the serum creatinine (Cr) level was reviewed in the each renal insufficiency group between the preoperative and post-operative time periods.

RESULTS

No increase in the serum Cr level was noted, and no patient required temporary or permanent hemodialysis, in any of the groups.

CONCLUSIONS

EVAR with contrast agents can be accomplished in patients with chronic renal insufficiency without hemodialysis; therefore,elevated Cr levels maynot be a contraindication in EVAR.

Percutaneous in situ oxygenated pump perfusion of a transplanted kidney during abdominal aortic aneurysm repair

The surgical management of aortic aneurysms in kidney transplant patients is a difficult clinical scenario where preservation of the kidney allograft during aortic cross-clamping is paramount. We describe a novel technique for renal protection during abdominal aortic aneurysm repair with in situ oxygenated pump perfusion of the transplanted kidney. A percutaneous approach is used for common femoral artery and vein cannulation and a cardiopulmonary bypass circuit to provide retrograde oxygenated pump perfusion to the transplanted kidney. This technique allows adequate kidney perfusion during warm ischemia and minimizes morbidity by using a percutaneous access technique.

Effects of study design and trends for EVAR versus OSR

Purpose:

To investigate if study design factors such as randomization, multi-center versus single center evidence, institutional surgical volume, and patient selection affect the outcomes for endovascular repair (EVAR) versus open surgical repair (OSR). Finally, we investigate trends over time in EVAR versus OSR outcomes.

Methods:

Search strategies for comparative studies were performed individually for: OVID’s MEDLINE, EMBASE, CINAHL, HAPI, and Evidence Based Medicine (EBM) Reviews (including Cochrane DSR, ACP Journal Club, DARE and CCTR), limited to 1990 and November 2006.

Results:

Identified literature: 84 comparative studies pertaining to 57,645 patients. These include 4 randomized controlled trials (RCTs), plus 2 RCTs with long-term follow-up. The other 78 comparative studies were nonrandomized with 75 reporting perioperative outcomes, of which 16 were multi-center, and 59 single-center studies. Of the single-center studies 31 were low-volume and 28 were high-volume centers. In addition, 5 studies had all patients anatomically eligible for EVAR, and 8 studies included high-risk patients only. Finally, 25 long term observational studies reported outcomes up to 3 years.

Outcomes:

Lower perioperative mortality and rates of complications for EVAR versus OSR varied across study designs and patient populations. EVAR adverse outcomes have decreased in recent times.

Conclusion:

EVAR highlights the problem of performing meta-analysis when the experience evolves over time.

Effect of Preoperative Renal Dysfunction on Mortality and Postoperative Renal Failure Following Endovascular Abdominal Aortic Aneurysm Repair

This study was aimed to assess the effect of preoperative renal dysfunction on mortality and postoperative renal failure in patients undergoing elective endovascular repair of abdominal aortic aneurysm. A total of 155 patients with a mean age of 74.9 years (±6.4) were included. In all, 31 patients (20%) had a preoperative creatinine level of >1.5 mg/dL, whereas 66 patients (42.6%) had an estimated glomerular filtration rate of <60 mL/min. Perioperative mortality was 2.6% with no significant difference between those with and without abnormal renal indices. Long-term survival at 4 years was 30% in patients with creatinine >1.5 mg/dL compared to over 60% in those with normal creatinine ( P < .02). The difference in long-term survival was not as significant in patients with normal or reduced glomerular filtration rate ( P = .13). However, neither creatinine nor glomerular filtration rate were found to accurately predict survival even though both demonstrated strong predictivity for postoperative renal failure in patients undergoing elective endovascular repair of abdominal aortic aneurysm.

Comparison of the effects of open and endovascular aortic aneurysm repair on long-term renal function using chronic kidney disease staging based on glomerular filtration rate

OBJECTIVE

It has been suggested that endovascular aneurysm repair (EVAR) in concert with serial contrast-enhanced computed tomography (CT) surveillance adversely impacts renal function. Our primary objectives were to assess serial renal function in patients undergoing EVAR and open repair (OR) and to evaluate the relative effects of method of repair on renal function.

METHODS

A thorough retrospective chart review was performed on 223 consecutive patients (103 EVAR, 120 OR) who underwent abdominal aortic aneurysm (AAA) repair. Demographics, pertinent risk factors, CT scan number, morbidity, and mortality were recorded in a database. Baseline, 30- and 90-day, and most recent glomerular filtration rate (GFR) were calculated. Mean GFR changes and renal function decline (using Chronic Kidney Disease [CKD] staging and Kaplan-Meier plot) were determined. EVAR and OR patients were compared. CKD prevalence (>or=stage 3, National Kidney Foundation) was determined before repair and in longitudinal follow-up. Observed-expected (OE) ratios for CKD were calculated for EVAR and OR patients by comparing observed CKD prevalence with the expected, age-adjusted prevalence.

RESULTS

The only baseline difference between EVAR and OR cohorts was female gender (4% vs 12%, P = .029). Thirty-day GFR was significantly reduced in OR patients (P = .047), but it recovered and there were no differences in mean GFR at a mean follow-up of 23.2 months. However, 18% to 39% of patients in the EVAR and OR groups developed significant renal function decline over time depending on its definition. OE ratios for CKD prevalence were greater in AAA patients at baseline (OE 1.28-3.23, depending upon age group). During follow-up, the prevalence and severity of CKD increased regardless of method of repair (OE 1.8-9.0). Deterioration of renal function was independently associated with age >70 years in all patients (RR 2.92) and performance of EVAR compared with OR (RR 3.5) during long-term follow-up.

CONCLUSIONS

Compared with EVAR, OR was associated with a significant but transient fall in GFR at 30 days. Renal function decline after AAA repair was common, regardless of method, especially in patients >70 years of age. However, the renal function decline was significantly greater by Kaplan-Meier analysis in EVAR than OR patients during long-term follow-up. More aggressive strategies to monitor and preserve renal function after AAA repair are warranted.

Impact of mild acute kidney injury (AKI) on outcome after open repair of aortic aneurysms

Recently, mild AKI has been considered as a risk factor for mortality in different scenarios. We conducted a retrospective analysis of the risk factors for two distinct definitions of AKI after elective repair of aortic aneurysms. Logistic regression was carried out to identify independent risk factors for AKI (defined as $25% or $50% increase in baseline SCr within 48 h after surgery, AKI 25% and AKI 50%, respectively) and for mortality. Of 77 patients studied (mean age 68 +/- 10, 83% male), 57% developed AKI 25% and 33.7% AKI 50%. There were no differences between AKI and control groups regarding comorbidities and diameter of aneurysms. However, AKI patients needed a supra-renal aortic cross-clamping more frequently and were more severely ill. Overall in-hospital mortality was 27.3%, which was markedly higher in those requiring a supra-renal aortic cross-clamping. The risk factors for AKI 25% were supra-renal aortic cross-clamping (odds ratio 5.51, 95% CI 1.05-36.12, p = 0.04) and duration of operation for AKI 25% (OR 6.67, 95% CI 2.23-19.9, p < 0.001). For AKI 50%, in addition to those factors, post-operative use of vasoactive drugs remained as an independent factor (OR 6.13, 95% CI 1.64-22.8, p = 0.005). The risk factors associated with mortality were need of supra-renal aortic cross-clamping (OR 9.6, 95% CI 1.37-67.88, p = 0.02), development of AKI 50% (OR 8.84, 95% CI 1.31-59.39, p = 0.02), baseline GFR lower than 49 mL/min (OR 17.07, 95% CI 2.00-145.23, p = 0.009), and serum glucose > 118 mg/dL in the post-operative period (OR 19.99, 95% CI 2.32-172.28, p = 0.006). An increase of at least 50% in baseline SCr is a common event after surgical repair of aortic aneurysms, particularly when a supra-renal aortic cross-clamping is needed. Along with baseline moderate chronic renal failure, AKI is an independent factor contributing to the high mortality found in this scenario.

The Durability of Evar — What are the Evidence and Implications on Follow-Up?

Background and Aims:

To investigate the durability of EVAR and to explore the evidence for follow-up investigations. Furthermore, to study the patients' impressions of follow-up investigations, and how complications and secondary procedures influence cost-effectiveness.

Material and Methods:

263 patients were treated by EVAR from february 1995-february 2007. The series is divided into two groups with the year 2000 as a cut-off point since a new generation of stent grafts was then introduced. Early and late complications and secondary procedures were recorded. A questionnaire study was performed to investigate the patients' views on the follow-up program.

Results:

There was a significant reduction of complications from period I to period II, which was also reflected in the reduction of secondary procedures. Freedom from secondary procedures were 47% and 93% at 5 years follow-up in the two periods, respectively. In phase II, 7.5% of the patients needed a secondary procedure. Limb extension and femoro-femoral bypass were the most common procedures. Since late complications still occur, and can be unpredictable, a follow-up program is necessary. The vast majority of the patients tolerated the follow-up program well.

Conclusions:

Although the number of complications following EVAR has decreased significantly over the years, a thorough follow-up program is still necessary. This follow-up regime is well tolerated by the patients. Reduction of secondary procedures is important to improve the cost-effectiveness of EVAR.

A meta-analysis of 21 178 patients undergoing open or endovascular repair of abdominal aortic aneurysm

Background

Several studies have compared outcomes after elective open and endovascular approaches to abdominal aortic aneurysm (AAA) surgery, with varying results.

Methods

A random-effects meta-analysis was undertaken to compare operative outcomes, postoperative complications, 30-day mortality and long-term patient survival after surgery. Endpoints were compared using odds ratios (ORs), weighted mean differences (WMDs) or log hazard ratios (HRs) as appropriate.

Results

Forty-two studies comprising 21 178 patients (10 855 open; 10 323 endovascular) were included. In the elective setting (20 715 patients), the endovascular method was associated with a shorter stay in intensive care (WMD − 36 h; P &lt; 0·001) and a shorter total postoperative stay (WMD − 5·4 days; P &lt; 0·001). Cardiac (OR 1·76; P = 0·002) and respiratory (OR 4·01; P &lt; 0·001) complications were more common after open surgery. In the endovascular group, 30-day mortality was lower (OR 0·46; P &lt; 0·001). Endovascular surgery was also associated with an improved long-term aneurysm-related mortality (HR 0·39; P &lt; 0·001). For ruptured AAA (463 patients), the less invasive operation was associated with a reduced stay in intensive care (WMD − 100·4 h; P = 0·005) and a significantly lower 30-day mortality (OR 0·45; P = 0·005).

Conclusions

The endovascular repair of AAA offers a clear benefit in terms of reduction in postoperative adverse events and 30-day mortality. In the longer term, it is also associated with a reduction in aneurysm-related mortality, but not in all-cause mortality.

Physiologic Monitoring Data: Will it Change our Follow-up Paradigms?

The purpose of endovascular aortic aneurysm repair is to depressurize the sac and to protect it from rupture. However, none of the imaging modality currently used during the follow-up period including CTA, MRA and duplex ultrasound can measure sac pressure. Noninvasive sac pressure monitoring using implantable sensors has the potential to provide a safe, reliable, cost-effective alternative for post-EVAR surveillance. The technology is compatible with all types of imaging, all types of implants, and allows clinicians to obtain physiologic data to supplement their assessment of the aneurysm repair. These devices may ultimately allow for measurements to be obtained at home, with an unlimited frequency without risk to the patient, added cost or complexity. We believe that not only is development of an intrasac transducer necessary, but it is a desirable adjunct to endovascular aneurysm repair, and an adjunct that might possibly eliminate some of the complex imaging protocols that are presently necessary over long-term follow-up.