Utility of surgery for ruptured abdominal aortic aneurysm

Systematic review and meta-analysis of the risk of bowel ischemia after ruptured abdominal aortic aneurysm repair

OBJECTIVE

Outcomes after repair of ruptured abdominal aortic aneurysm (RAAA) have improved in the last decade. It is unknown whether this has resulted in a reduction of postoperative bowel ischemia (BI). The primary objective was to determine BI prevalence after RAAA repair. Secondary objectives were to determine its major sequelae and differences between open repair (OR) and endovascular aneurysm repair (EVAR).

METHODS

This systematic review (PROSPERO CRD42017055920) followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. MEDLINE and Embase were searched for studies published from 2005 until 2018. The methodologic quality of observational studies was assessed with the Methodological Index for Non-Randomized Studies (MINORS) tool. The quality of the randomized controlled trials (RCTs) was assessed with the Cochrane Collaboration's tool for assessing risk of bias. BI prevalence and rates of BI as cause of death, reoperation, and bowel resection were estimated with meta-analyses with a random-effects model. Differences between OR and EVAR were estimated with pooled risk ratios with 95% confidence intervals (CIs). Changes over time were assessed with Spearman rank test (ρ). Publication bias was assessed with a funnel plot analysis.

RESULTS

A total of 101 studies with 52,670 patients were included; 72 studies were retrospective cohort studies, 14 studies were prospective cohort studies, 12 studies were retrospective administrative database studies, and 3 studies were RCTs. The overall methodologic quality of the RCTs was high, but that of observational studies was low. The pooled prevalence of BI ranged from of 0.08 (95% CI, 0.07-0.09) in database studies to 0.10 (95% CI, 0.08-0.12) in cohort studies. The risk of BI was higher after OR than after EVAR (risk ratio, 1.79; 95% CI, 1.25-2.57). The pooled rate of BI as cause of death was 0.04 (95% CI, 0.03-0.05), and that of BI as cause of reoperation and bowel resection ranged between 0.05 and 0.07. BI prevalence did not change over time (ρ, -0.01; P = .93). The funnel plot analysis was highly suggestive of publication bias.

CONCLUSIONS

The prevalence of clinically relevant BI after RAAA repair is approximately 10%. Approximately 5% of patients undergoing RAAA repair suffer from severe consequences of BI. BI is less prevalent after EVAR than after OR.

Association of hospital structures with mortality from ruptured abdominal aortic aneurysm

BACKGROUND

There is significant variation in the mortality rates of patients with a ruptured abdominal aortic aneurysm (rAAA) admitted to hospital in England. This study sought to investigate whether modifiable differences in hospital structures and processes were associated with differences in patient outcome.

METHODS

Patients diagnosed with rAAA between 2005 and 2010 were extracted from the Hospital Episode Statistics database. After risk adjustment, hospitals were grouped into low-mortality outlier, expected mortality and high-mortality outlier categories. Hospital Trust-level structure and process variables were compared between categories, and tested for an association with risk-adjusted 90-day mortality and non-corrective treatment (palliation) rate using binary logistic regression models.

RESULTS

There were 9877 patients admitted to 153 English NHS Trusts with an rAAA during the study. The overall combined (operative and non-operative) mortality rate was 67·5 per cent (palliation rate 41·6 per cent). Seven hospital Trusts (4·6 per cent) were high-mortality and 15 (9·8 per cent) were low-mortality outliers. Low-mortality outliers used significantly greater mean resources per bed (doctors: 0·922 versus 0·513, P < 0·001; consultant doctors: 0·316 versus 0·168, P < 0·001; nurses: 2·341 versus 1·770, P < 0·001; critical care beds: 0·045 versus 0·019, P < 0·001; operating theatres: 0·027 versus 0·019, P = 0·002) and performed more fluoroscopies (mean 12·6 versus 9·2 per bed; P = 0·046) than high-mortality outlier hospital Trusts. On multivariable analysis, greater numbers of consultants, nurses and fluoroscopies, teaching status, weekday admission and rAAA volume were independent predictors of lower mortality and, excluding rAAA volume, a lower rate of palliation.

CONCLUSION

The variability in rAAA outcome in English National Health Service hospital Trusts is associated with modifiable hospital resources. Such information should be used to inform any proposed quality improvement programme surrounding rAAA.

Effect of gender on long-term survival after abdominal aortic aneurysm repair based on results from the Medicare national database

OBJECTIVES

Historically, women have higher procedurally related mortality rates than men for abdominal aortic aneurysm (AAA) repair. Although endovascular aneurysm repair (EVAR) has improved these rates for men and women, effects of gender on long-term survival with different types of AAA repair, such as EVAR vs open aneurysm repair (OAR), need further investigation. To address this issue, we analyzed survival in matched cohorts who received EVAR or OAR for both elective (eAAA) and ruptured AAA (rAAA).

METHODS

Using the Medicare Beneficiary Database (1995-2006), we compiled a cohort of patients who underwent OAR or EVAR for eAAA (n = 322,892) or rAAA (n = 48,865). Men and women were matched by propensity scores, accounting for baseline demographics, comorbid conditions, treating institution, and surgeon experience. Frailty models were used to compare long-term survival of the matched groups.

RESULTS

Perioperative mortality for eAAAs was significantly lower among EVAR vs OAR recipients for both men (1.84% vs 4.80%) and women (3.19% vs 6.37%, P < .0001). One difference, however, was that the survival benefit of EVAR was sustained for the 6 years of follow-up in women but disappeared in 2 years in men. Similarly, the survival benefit of men vs women after elective EVAR disappeared after 1.5 to 2 years. For rAAAs, 30-day mortality was significantly lower for EVAR recipients compared with OAR recipients, for both men (33.43% vs 43.70% P < .0001) and women (41.01% vs 48.28%, P = .0201). Six-year survival was significantly higher for men who received EVAR vs those who received OAR (P = .001). However, the survival benefit for women who received EVAR compared with OAR disappeared in 6 months. Survival was also substantially higher for men than women after emergent EVAR (P = .0007).

CONCLUSIONS

Gender disparity is evident from long-term outcomes after AAA repair. In the case for rAAA, where the long-term outcome for women was significantly worse than for men, the less invasive EVAR treatment did not appear to benefit women to the same extent that it did for men. Although the long-term outcome after open repair for elective AAA was also worse for women, EVAR benefit for women was sustained longer than for men. These associations require further study to isolate specific risk factors that would be potential targets for improving AAA management.

Defining perioperative mortality after open and endovascular aortic aneurysm repair in the US Medicare population

BACKGROUND

Perioperative mortality is reported after abdominal aortic aneurysm (AAA) repair, but there is no agreed upon standard definition. Often, 30-day mortality is reported because in-hospital mortality may be biased in favor of endovascular repair given the shorter length of stay. However, the duration of increased risk of death after aneurysm repair is unknown.

STUDY DESIGN

We used propensity score modeling to create matched cohorts of US Medicare beneficiaries undergoing endovascular (n = 22,830) and open (n = 22,830) AAA repair from 2001 to 2004. We calculated perioperative mortality using several definitions including in-hospital, 30-day, and combined 30-day and in-hospital mortality. We determined the relative risk (RR) of death after open compared with endovascular repair as well as the absolute mortality difference. To define the duration of increased risk we calculated biweekly interval death rates for 12 months.

RESULTS

In-hospital, 30-day, and combined 30-day and in-hospital mortality for open and endovascular repair were 4.6% versus 1.1%, 4.8% versus 1.6%, and 5.3% versus 1.7%, respectively. The absolute differences in mortality were similar, at 3.5%, 3.2%, and 3.7%. The RRs of death (95% confidence interval) were 4.2 (3.6 to 4.8), 3.1 (2.7 to 3.4), and 3.2 (2.8 to 3.5). Biweekly interval death rates were highest during the first month after endovascular repair (0.6%) and during the first 2.5 months (0.5% to 2.1%) after open repair. After 2.5 months, rates were similar for both repairs (<0.5%) and stabilized after 3 months. The 90-day mortality rates for open and endovascular repair were 7.0% and 3.2%, respectively.

CONCLUSIONS

In-hospital mortality comparisons overestimate the benefit of endovascular repair compared with 30-day or combined 30-day and in-hospital mortality. The total mortality impact of AAA repair is not realized until 3 months after repair and the duration of highest mortality risk extends longer for open repair.

Improved Long-Term Survival After Abdominal Aortic Aneurysm Repair

Background— Treatment of abdominal aortic aneurysm (AAA) has changed significantly over the past 2 decades. In this perspective, time trends in long-term survival were studied.

Methods and Results— We identified 8663 primary intact and 4171 ruptured AAA repairs in the Swedish Vascular Registry from 1987 to 2005. Mortality was obtained from the national population registry. Crude survival was analyzed, including all mortality. To analyze the long-term outcome among those surviving the AAA repair, relative survival, which denotes the survival rate of patients compared with that of the general population adjusted for age, sex, and calendar year, was calculated, excluding 90-day mortality. In a comparison of AAA repairs from 1987 to 1999 and 2000 to 2005, age (71.4 versus 72.5 years; P <0.001), patients with comorbidities (65.0% versus 68.5%; P <0.001), and endovascular repair (1.6% versus 17.0%; P <0.001) increased. After intact AAA repair, crude 5-year survival was 69.0% (99% confidence interval [CI], 67.7 to 70.4), and relative 5-year survival excluding 90-day mortality was 90.3% (99% CI, 88.6 to 92.0). Relative 5-year survival was better for those operated on from 2000 to 2005 compared with 1987 to 1999 (difference, 4.7%; 99% CI, 1.3 to 8.1), for men versus women (4.6%; 99% CI, 0.4 to 8.8), and for octogenarians versus patients <80 years of age (10.2%; 99% CI, 1.5 to 18.8); no difference was observed between open and endovascular repair (6.0%; 99% CI, −1.5 to 13.4). After ruptured AAA repair, crude 5-year survival was 41.7% (99% CI, 39.6 to 43.7) and relative 5-year survival was 87.1% (99% CI, 83.9 to 90.3). No significant differences in relative 5-year survival were observed between time periods, sex, or age groups.

Conclusions— Long-term survival improved over time after intact AAA repair despite a change in case mix toward older patients with more comorbidities. Long-term survival was stable after ruptured AAA repair.

Ruptured Abdominal Aortic Aneurysms in Community Practice: Age and Operative Variables Predict Survival

Our objective is to determine if the mortality and functional outcome of patients with ruptured abdominal aortic aneurysms treated at community hospitals is more a function of patient factors and comorbidities or hospital system and surgeon-controlled variables. We used a retrospective review of all patients with infrarenal ruptured abdominal aortic aneurysms treated at three large community hospitals in Chicago from 1996 to 2005. There was an overall 58 per cent mortality rate. There was a statistically significant difference in the age of those who lived (69 ± 9.8) and those who died (78 ± 7.9, P = 0.0005). Mortality was found to increase with each increasing decade of life. None of the patients from age 50 to 60 died, whereas 44 per cent of the patients from 61 to 70, 65 per cent of those 71 to 80, 64 per cent of those 81 to 90, and 100 per cent of those older than 90 died. There was an increased hazard ratio of 10.9 times the risk of mortality once a patient became older than age 70 (P = 0.02). Intra-operative variables did influence survival: duration of surgery (lived 230 ± 78 minutes, died 324 ± 130 minutes, P = 0.006), intra-operative blood loss (lived 1894 ± 1014 mL, died 5692 ± 3018 mL, P = 0.00003), and blood transfusion (lived 6.7 ± 2.8 units, died 10.5 ± 3.7 units, P = 0.0006). Age and intra-operative factors play a major role in the survival or mortality of patients with ruptured abdominal aortic aneurysms. Short operative time combined with minimizing blood loss and transfusion requirements improve survival, especially in the elderly.