Effect of regional cooperation on outcomes from ruptured abdominal aortic aneurysm

The Role of Integrated Air Transport System in Managing Patients with Abdominal Aortic Aneurysm Rupture

OBJECTIVE

Ruptured abdominal aortic aneurysms (rAAAs) are highly morbid emergencies. Not all hospitals are equipped to repair them, and an air ambulance network may aid in regionalising specialty care to quaternary referral centres. The association between travel distance by air ambulance and rAAA mortality in patients transferred as an emergency for repair was examined.

METHODS

A retrospective review of institutional data. Adults with rAAA (2002 - 2019) transferred from an outside hospital (OSH) to a single quaternary referral centre for repair via air ambulance were identified. Patients who arrived via ground transport or post-repair at an OSH for continued critical care were excluded. Patients were divided into near and far groups based on the 75th percentile of the straight line travel distance (> 72 miles) between hospitals. The primary outcome was 30 day mortality. Multivariable logistic regression was used to assess the association between distance and mortality after adjusting for age, sex, ethnicity, cardiovascular comorbidities, and repair type.

RESULTS

A total of 290 patients with rAAA were transported a median distance of 40.4 miles (interquartile range 25.5, 72.7) with 215 (74.1%) near and 75 (25.9%) far patients. Both the near and far groups had similar ages, sex, and ethnicity. There was no difference in pre-operative loss of consciousness, intubation, or cardiac arrest between groups. Endovascular aneurysm repair utilisation and intra-operative aortic occlusion balloon use were also similar. Neither the observed (26.8% vs. 23.9%, p = .61) nor the adjusted odds ratio (0.70, 95% confidence interval 0.36 - 1.39, p = .32) 30 day mortality rate differed significantly between the near and far groups.

CONCLUSION

Increasing distance travelled during transfer by air ambulance was not associated with worse outcomes in patients with rAAA. The findings support the regionalisation of rAAA repair to large quaternary centres via an integrated and robust air ambulance network.

The Relationship Between Operative Volume and Peri-operative Mortality After Non-elective Aortic Aneurysm Repair in Australia

OBJECTIVE

Hospital and surgeon operative caseload is thought to be associated with peri-operative mortality following the non-elective repair of aortic aneurysms; however, whether such an association exists within the Australian healthcare setting is unknown.

METHODS

The Australasian Vascular Audit was interrogated to identify patients undergoing non-elective (emergency [EMG] or semi-urgent [URG]) aortic aneurysm repair between 2010 and 2016, as well as their treating surgeon and hospital. Hierarchal logistic regression modelling was used to assess the impact of caseload on outcomes after both endovascular (EVAR) and open surgical repair (OSR).

RESULTS

Volume counts were determined from 14 262 patients (4 121 OSR and 10 141 EVAR). After exclusion of elective procedures and duplicates, 1 153 EVAR (570 EMG and 583 URG) and 1 245 OSR (946 EMG and 299 URG) non-elective cases remained for the analysis. Crude mortality was 24.0% following OSR (EMG 29.2%; URG 7.7%) and 7.5% following EVAR (EMG 12.6%; URG 2.4%). Univariable analysis demonstrated an association between OSR mortality and hospital volume (quintile [Q] 1: 25.3%, Q2: 27.8%, Q3: 23.9%, Q4: 27.0%, Q5: 16.2%; p = .030), but not surgeon (Q1: 25.2%, Q2: 27.4%, Q3: 26.0%, Q4: 21.4%, Q5: 19.5%, p = .32). Multivariable analysis confirmed this association (odds ratio (OR) [95% CI]; Q1 vs 5: 1.91 [1.13-3.21], Q2 vs. 5: 2.01[1.24-3.25], Q3 vs. 5: 1.41 [0.86-2.29], Q4 vs. 5: 1.92 [1.17-3.15]; p = .020). The difference was most pronounced in the EMG OSR group [Q1 - 3 vs. 4-5] (OR 1.63 [1.07-2.48]; p = .020). Mortality after EVAR was not associated with either hospital (Q1: 6.3%, Q2: 10%, Q3: 6.8%, Q4: 4.5%, Q5: 10%; p = .14) or surgeon volume (Q1: 9.3%, Q2: 5.7%, Q3: 8.1%, Q4: 7.0%, Q5: 7.3%; p = .67).

CONCLUSION

There is an inverse correlation between hospital volume and peri-operative mortality following EMG open repair of aortic aneurysm. These data support restructuring Australian pathways of care to direct suspected ruptured aneurysm to institutions that reach a minimum volume threshold.

Value of risk scores in the decision to palliate patients with ruptured abdominal aortic aneurysm

Background

The aim of this study was to develop a 48‐h mortality risk score, which included morphology data, for patients with ruptured abdominal aortic aneurysm presenting to an emergency department, and to assess its predictive accuracy and clinical effectiveness in triaging patients to immediate aneurysm repair, transfer or palliative care.

Methods

Data from patients in the IMPROVE (Immediate Management of the Patient With Ruptured Aneurysm: Open Versus Endovascular Repair) randomized trial were used to develop the risk score. Variables considered included age, sex, haemodynamic markers and aortic morphology. Backwards selection was used to identify relevant predictors. Predictive performance was assessed using calibration plots and the C‐statistic. Validation of the newly developed and other previously published scores was conducted in four external populations. The net benefit of treating patients based on a risk threshold compared with treating none was quantified.

Results

Data from 536 patients in the IMPROVE trial were included. The final variables retained were age, sex, haemoglobin level, serum creatinine level, systolic BP, aortic neck length and angle, and acute myocardial ischaemia. The discrimination of the score for 48‐h mortality in the IMPROVE data was reasonable (C‐statistic 0·710, 95 per cent c.i. 0·659 to 0·760), but varied in external populations (from 0·652 to 0·761). The new score outperformed other published risk scores in some, but not all, populations. An 8 (95 per cent c.i. 5 to 11) per cent improvement in the C‐statistic was estimated compared with using age alone.

Conclusion

The assessed risk scores did not have sufficient accuracy to enable potentially life‐saving decisions to be made regarding intervention. Focus should therefore shift to offering repair to more patients and reducing non‐intervention rates, while respecting the wishes of the patient and family.

Not much help

Development and External Validation of a Model Predicting Death After Surgery in Patients With a Ruptured Abdominal Aortic Aneurysm: The Dutch Aneurysm Score

OBJECTIVE

The decision whether or not to proceed with surgical intervention of a patient with a ruptured abdominal aortic aneurysm (rAAA) is very difficult in daily practice. The primary objective of the present study was to develop and to externally validate a new prediction model: the Dutch Aneurysm Score (DAS).

METHODS

With a prospective cohort of 10 hospitals (n = 508) the DAS was developed using a multivariate logistic regression model. Two retrospective cohorts with rAAA patients from two hospitals (n = 373) were used for external validation. The primary outcome was the combined 30 day and in-hospital death rate. Discrimination (AUC), calibration plots, and the ability to identify high risk patients were compared with the more commonly used Glasgow Aneurysm Score (GAS).

RESULTS

After multivariate logistic regression, four pre-operative variables were identified: age, lowest in hospital systolic blood pressure, cardiopulmonary resuscitation, and haemoglobin level. The area under the receiver operating curve (AUC) for the DAS was 0.77 (95% CI 0.72-0.82) compared with the GAS with an AUC of 0.72 (95% CI 0.67-0.77). The DAS showed a death rate in patients with a predicted death rate ≥80% of 83%.

CONCLUSIONS

The present study shows that the DAS has a higher discriminative performance (AUC) compared with the GAS. All clinical variables used for the DAS are easy to obtain. Identification of low risk patients with the DAS can potentially reduce turndown rates. The DAS can reliably be used by clinicians to make a more informed decision in dialogue with the patient and their family whether or not to proceed with surgical intervention.

Midterm Re-interventions and Survival After Endovascular Versus Open Repair for Ruptured Abdominal Aortic Aneurysm

OBJECTIVE

To compare the midterm re-intervention and survival rates after EVAR and OR for ruptured abdominal aortic aneurysms (RAAA).

METHODS

Observational cohort study including all consecutive RAAA patients between 2004 and 2011 in 10 hospitals in the Amsterdam ambulance region. The primary end point was re-interventions within 5 years of the primary intervention. The secondary end point was death. The outcomes were estimated by survival analyses, compared using the logrank test, and subsequently adjusted for possible confounders using Cox proportional hazard models. Re-interventions were estimated in all patients and in patients who survived their hospital stay.

RESULTS

Of 467 patients with a RAAA, 73 were treated by EVAR and 394 by OR. Five years after the primary intervention, the rates of freedom from re-intervention were 55% for EVAR (26/73, 95% CI: 41-69%) and 60% for OR (130/394, 95% CI: 55-66%) (p = .96). After adjustment for age, sex, comorbidity, and pre-operative hemodynamic stability, the risk of re-intervention was similar (HR 1.01, 95% CI: 0.65-1.55). The survival rates were 36% for EVAR (45/73, 95% CI: 24-47%) and 38% for OR (235/394, 95% CI: 33-43%) (p = .83). In 297 patients who survived their hospital stay, the rates of freedom from re-intervention were 66% for EVAR (15/54, 95% CI: 52-81%) and 90% for OR (20/243, 95% CI: 86-95%) (p < .01). After adjustment for age and sex, the risk of re-intervention was higher after EVAR (HR 0.27, 95% CI: 0.14-0.52).

CONCLUSIONS

Five years after the primary intervention, endovascular and open repair for ruptured abdominal aortic aneurysm resulted in similar re-intervention and survival rates. However, in patients who survived their hospital stay the re-intervention rate was higher for EVAR than for OR.

Acute kidney injury defined according to the 'Risk,' 'Injury,' 'Failure,' 'Loss,' and 'End-stage' (RIFLE) criteria after repair for a ruptured abdominal aortic aneurysm

OBJECTIVE

Acute kidney injury (AKI) is a serious complication after repair of a ruptured abdominal aortic aneurysm (RAAA). In the present Society for Vascular Surgery (SVS)/International Society for CardioVascular Surgery (ISCVS) reporting standards patients are classified as no dialysis (grade I), as temporary dialysis (grade II), and as permanent dialysis or fatal outcome (grade III). However, AKI is a broad clinical syndrome including more than the requirement for renal replacement therapy. The recently introduced 'Risk,' 'Injury,' 'Failure,' 'Loss,' and 'End-stage' (RIFLE) classification for AKI comprises three severity categories based on serum creatinine and urine output ('Risk,' 'Injury,' and 'Failure'). The objective of the present study was to assess the incidence of AKI using the RIFLE criteria (AKIRIFLE). Secondary objectives were to assess the incidence of AKI as defined using the SVS/ISCVS reporting standards (AKISVS/ISCVS) and the association between AKIRIFLE and death.

METHODS

This was an observational cohort study in 362 consecutive patients with an RAAA in three hospitals in Amsterdam (The Netherlands) between 2004 and 2011. The end points were the incidence of AKIRIFLE, of AKISVS/ISCVS, and the combined 30-day or in-hospital death rate. A multivariable logistic regression model was made to assess the association between AKIRIFLE and death after adjustment for preoperative shock profile (Glasgow Aneurysm Score) and postoperative shock profile (Acute Physiology and Chronic Health Evaluation [APACHE] II score, use of vasopressors, and fluid balance during the first 24 hours after intervention).

RESULTS

AKIRIFLE occurred in 74% (267/362; 95% confidence interval [CI], 69%-78%), with 27% of these patients categorized as 'Risk' (71/267; 95% CI, 22%-32%), 39% categorized as 'Injury' (104/267, 95% CI, 33%-45%), and 34% categorized as 'Failure' (92/267; 95% CI, 29%-40%). AKISVS/ISCVS occurred in 48% (175/362; 95% CI, 43%-53%), with 53% of these categorized as 'grade I' (92/175; 95% CI, 45%-60%), 19% as 'grade II' (34/175; 95% CI, 14%-26%), and 28% as 'grade III' (49/175; 95% CI, 22%-35%). After multivariable adjustment for shock profiles the risk of dying in patients categorized as AKIRIFLE 'Failure' was greater than in patients without AKIRIFLE (adjusted odds ratio, 6.360; 95% CI, 2.231-18.130).

CONCLUSIONS

The incidence of AKI defined according to the RIFLE criteria (74%) was greater than defined using the SVS/ISCVS reporting standards (48%) and patients categorized as 'Failure' using the RIFLE criteria had a greater risk of dying than patients without AKI. These results indicate that the problem of AKI is much bigger than previously anticipated and that minimizing injury to the kidney could be an important focus of future research on reducing the death rate after RAAA repair.