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Preoperative risk score for the prediction of mortality after repair of ruptured abdominal aortic aneurysms

Open ArchivePublished:May 09, 2018DOI:https://doi.org/10.1016/j.jvs.2017.12.075

      Abstract

      Objective

      Even in the ruptured endovascular aneurysm repair first era, there are still patients who will not survive their ruptured abdominal aortic aneurysm (rAAA). All previously published mortality risk scores include intraoperative variables and are not helpful with the decision to operate or in providing preoperative patient and family counseling. The purpose of this study was to develop a practical preoperative risk score to predict mortality after repair of rAAA.

      Methods

      Data of all patients with rAAA presenting between January 1, 2002, and October 31, 2013, were collected. Logistic regression was used to evaluate predictive variables both univariately and jointly, and the results of multivariate models guided the definition of the final simplified scoring algorithm.

      Results

      There were 303 patients who presented during the study period. Sixteen patients died in the emergency department, en route to surgery, or after choosing comfort care. Preoperative variables most predictive of mortality were age >76 years (odds ratio [OR], 2.11; confidence interval [CI], 1.47-4.97; P = .011), creatinine concentration >2.0 mg/dL (OR, 3.66; CI, 1.85-7.24; P < .001), pH <7.2 (OR, 2.58; CI, 1.27-5.24; P = .009), and systolic blood pressure ever <70 mm Hg (OR, 2.70; CI, 1.46-4.97; P = .002). Assigning 1 point for each variable, patients were stratified according to the preoperative rAAA mortality risk score (range, 0-4). For all repairs, at 30 days, patients with 1 point suffered 22% mortality; 2 points, 69% mortality; and 3 points, 80% mortality. All patients with 4 points died. There was a mortality benefit for ruptured endovascular aneurysm repair across all categories.

      Conclusions

      Our rAAA mortality risk score is based on four variables readily assessed in the emergency department and allows accurate prediction of 30-day mortality after repair of rAAAs. It also has a direct impact on clinical decision-making by adding prognostic information to the decision to transfer patients to tertiary care centers and aiding in preoperative discussions with patients and their families.

      Graphical abstract

      Keywords

      Article Highlights
      • Type of Research: Retrospective single-center cohort study
      • Take Home Message: In an analysis of 303 patients who presented with a ruptured abdominal aortic aneurysm, four preoperative variables were identified that were most predictive of mortality (age >76 years, creatinine concentration >2 mg/dL, pH <7.2, systolic blood pressure <70 mm Hg), and when applied as a risk score of 1 to 4, they predicted increasing mortality from 22% to 69%, 80%, and 100%, respectively.
      • Recommendation: This study suggests that a risk score using four preoperative variables can predict risk of 30-day mortality in patients with ruptured abdominal aortic aneurysms.
      Ruptured abdominal aortic aneurysms (rAAAs) remain a leading cause of death in the United States and Europe, with mortality after ruptured open repair (rOR) reported as high as 80%.
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      Ruptured abdominal aortic aneurysm: the Harborview experience.
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      and survival benefit has been shown with the adoption of a ruptured endovascular aneurysm repair (rEVAR) first strategy,
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      • et al.
      Management of ruptured abdominal aortic aneurysm in the endovascular era.
      • Mayer D.
      • Aeschbacher S.
      • Pfammatter T.
      Complete replacement of open repair for ruptured abdominal aortic aneurysms by endovascular aneurysm repair. A two-center 14-year experience.
      multidisciplinary patient care protocols,
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      • Chang B.B.
      • Kreienberg P.B.
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      • et al.
      Establishing a protocol for endovascular treatment of ruptured abdominal aortic aneurysms: outcomes of a prospective analysis.
      • Moore R.
      • Nutley M.
      • Cina C.S.
      • Motamedi M.
      • Faris P.
      • Abuznadah W.
      Improved survival after introduction of an emergency endovascular therapy protocol for ruptured abdominal aortic aneurysms.
      • Oyague K.S.
      • Mubarak O.A.
      • Nowak L.R.
      • Gainer J.G.
      • Rehring T.F.
      • O'Brien M.M.
      • et al.
      Endovascular repair of ruptured and symptomatic abdominal aortic aneurysms using a structured protocol in a community teaching hospital.
      and regionalization of advanced aortic care.
      • Hill J.S.
      • McPhee J.T.
      • Messina L.M.
      • Ciocca R.G.
      • Eslami M.H.
      Regionalization of abdominal aortic aneurysm repair: evidence of a shift to high-volume centers in the endovascular era.
      • McPhee J.
      • Eslami M.H.
      • Arous E.J.
      • Messina L.M.
      • Schanzer A.
      Endovascular treatment of ruptured abdominal aortic aneurysms in the United States (2001-2006): a significant survival benefit over open repair is independently associated with increased institutional volume.
      Patients fortunate enough to qualify for rEVAR also have significant survival benefit,
      • Moore R.
      • Nutley M.
      • Cina C.S.
      • Motamedi M.
      • Faris P.
      • Abuznadah W.
      Improved survival after introduction of an emergency endovascular therapy protocol for ruptured abdominal aortic aneurysms.
      • McPhee J.
      • Eslami M.H.
      • Arous E.J.
      • Messina L.M.
      • Schanzer A.
      Endovascular treatment of ruptured abdominal aortic aneurysms in the United States (2001-2006): a significant survival benefit over open repair is independently associated with increased institutional volume.
      with mortality reported as low as 16% in some series.
      • Wallace G.A.
      • Starnes B.W.
      • Hatsukami T.S.
      • Quiroga E.
      • Tang G.L.
      • Kohler T.R.
      • et al.
      Favorable discharge disposition and survival after successful endovascular repair of ruptured abdominal aortic aneurysm.
      Despite these advancements, many patients will succumb to their rAAA regardless of the care they receive, and it remains difficult to tell who will live and who will die. Several risk scores have been derived to predict mortality after repair of rAAA, such as the Glasgow Aneurysm Score (GAS),
      • Samy A.K.
      • Murray G.
      • MacBain G.
      Glasgow aneurysm score.
      Hardman index,
      • Hardman D.T.
      • Fisher C.M.
      • Patel M.I.
      • Neale M.
      • Chambers J.
      • Lane R.
      • et al.
      Ruptured abdominal aortic aneurysms: who should be offered surgery?.
      Vancouver score,
      • Chen J.C.
      • Hildebrand H.D.
      • Salvian A.J.
      • Taylor D.C.
      • Strandberg S.
      • Myckatyn T.M.
      • et al.
      Predictors of death in nonruptured and ruptured abdominal aortic aneurysms.
      Edinburgh Ruptured Aneurysm Score,
      • Tambyraja A.
      • Murie J.
      • Chalmers R.
      Predictors of outcome after abdominal aortic aneurysm rupture: Edinburgh Ruptured Aneurysm Score.
      and Vascular Study Group of New England (VSGNE) rAAA risk score.
      • Robinson W.P.
      • Schanzer A.
      • Li Y.
      • Goodney P.P.
      • Nolan B.W.
      • Eslami M.H.
      • et al.
      Derivation and validation of a practical risk score for prediction of mortality after open repair of ruptured abdominal aortic aneurysms in a U.S. regional cohort and comparison to existing scoring systems.
      However, these scores have differing levels of clinical utility. The GAS has been found to not be predictive of mortality in the endovascular era,
      • Patterson B.O.
      • Karthikesalingam A.
      • Hinchliffe R.J.
      • Loftus I.M.
      • Thompson M.M.
      • Holt P.J.
      The Glasgow Aneurysm Score does not predict mortality after open abdominal aortic aneurysm in the era of endovascular aneurysm repair.
      • Tambyraja A.L.
      • Lee A.J.
      • Murie J.A.
      • Chalmers R.T.
      Prognostic scoring in ruptured abdominal aortic aneurysm: a prospective evaluation.
      and both the Hardman index and GAS fail to predict mortality in the highest risk populations.
      • Robinson W.P.
      • Schanzer A.
      • Li Y.
      • Goodney P.P.
      • Nolan B.W.
      • Eslami M.H.
      • et al.
      Derivation and validation of a practical risk score for prediction of mortality after open repair of ruptured abdominal aortic aneurysms in a U.S. regional cohort and comparison to existing scoring systems.
      The VSGNE score has been validated in the endovascular era, but it includes intraoperative variables, limiting its clinical utility in preoperative decision-making. We sought to develop a practical, clinically relevant preoperative rAAA mortality risk score to aid in clinical decision-making in the endovascular era.

      Methods

       Database

      Our institution prospectively maintains a ruptured aneurysm data set that includes all patients with a diagnosis of rAAA since January 1, 2002. The maintenance of this data set is approved by our Institutional Review Board, and patients provided written consent or consent was waived as indicated by our Institutional Review Board. Six independent data abstractors collect prehospital, emergency department, anesthetic, operative, radiographic, and follow-up data of all patients presenting with rAAAs.

       Cohort

      We completed a retrospective analysis of our institutional rAAA database including all patients presenting to our institution with ruptured aneurysms between January 1, 2002, and October 31, 2013. Whereas the database includes 145 patient-specific preoperative variables, we focused our analysis on a subset of those easily measured in the preoperative setting. In the setting of an rAAA, many variables will not be obtained, but we decided that certain core variables were always available, which included the following: age, hematocrit, systolic blood pressure (SBP) values from various time points, use of cardiopulmonary resuscitation, pH, international normalized ratio, creatinine concentration, temperature, partial thromboplastin time, weight, history of coronary artery disease, and loss of consciousness at any time.
      Each of the patients who had a preoperative computed tomography scan was reviewed by a single surgeon (B.W.S.), who determined whether the patient was eligible for EVAR on the basis of the following criteria: infrarenal neck length and diameter and access vessel size. The patient was classified as eligible for EVAR or not eligible.

       Statistical analysis

      We screened preoperative variables with univariate analysis against 30-day survival, using t-tests for continuous variables and χ2 tests for categorical variables. We discarded variables that failed to achieve statistical significance and variables with extensive missing data. Of the SBP measurements, we found “lowest prehospital SBP” to be the most predictive of survival, and we discarded the others.
      The remaining variables were analyzed simultaneously using logistic regression, including a term for repair type (rOR vs rEVAR) to control for its dramatic effect on the patients' outcomes. One rEVAR and one rOR patient were missing outcome data, a violation of the assumptions of logistic regression too minor to substantially influence the results of the analysis. Whereas type of repair had a noticeable effect on outcome, separate models predicting 30-day mortality based on type of repair did not yield statistical benefit. Only the variable age >76 years returned different estimated log odds ratios (ORs), and this was not statistically significant (Fig 1). As such, we cannot conclude that the more complex approach of fitting different models would improve on the simpler approach of a single model for both repair types.
      Figure thumbnail gr1
      Fig 1Multivariate logistic regression comparing predictors in separate models for ruptured endovascular aneurysm repair (EVAR) and ruptured open repair (rOR). SBP, Systolic blood pressure.
      The final model unambiguously indicated a smaller set of variables to include in a final algorithm; age, creatinine concentration, pH, and lowest prehospital SBP were highly statistically significant predictors of mortality. Of the remaining variables, only cardiopulmonary resuscitation had a P value approaching significance (.1). To achieve a practical risk score, these variables were dichotomized at standard levels, and logistic regression was used for the analysis. To ensure that dichotomized variables were not overly simplistic, the C statistic was evaluated for both dichotomized and continuous models, and the performance of the two models was comparable (Fig 2).
      Figure thumbnail gr2
      Fig 2Comparison of models with dichotomized vs continuous variables. AUC, Area under the curve.

      Results

      There were 303 patients who presented with rAAAs at our institution between 2002 and 2013. After 2007, patients were repaired according to an “EVAR first” protocol, with each attending surgeon determining the candidacy for endovascular repair. Our cohort was significantly male (80%), and 50% were older than 76 years. They presented with the typical vascular risk factors, including 65% with hypertension, 39% with coronary artery disease, and 22% with chronic obstructive pulmonary disease. A significant number of patients presented with signs of severe shock, including a preoperative heart rate >100 beats/min (23%), preoperative SBP <70 mm Hg (39%), loss of consciousness (30%), and cardiac arrest (14.5%; Table I). There were significant differences between the rEVAR and rOR cohorts with respect to pH <7.2, incidence of preoperative myocardial infarction, and previous aortic surgery.
      Table IDemographics, comorbidities, and prehospital characteristics of the patients
      All patients (N = 303), No. (%)rEVAR (n = 74), No. (%)rOR (n = 213), No. (%)
      Patient comorbidity
       Male242 (79.9)73 (98.6)151 (70.8)
       Age >76150 (49.5)39 (52.7)93 (43.7)
       Hypertension197 (65.0)60 (81.1)123 (57.7)
       Diabetes mellitus41 (13.5)15 (20.3)24 (11.3)
       Coronary artery disease119 (39.3)35 (47.3)73 (34.3)
       Chronic obstructive pulmonary disease67 (22.1)19 (25.7)42 (19.7)
       Dialysis dependent13 (4.3)3 (4.1)10 (4.7)
       B-blocker95 (31.4)26 (35.1)58 (27.2)
       Plavix12 (4.0)6 (8.1)4 (18.8)
       Statin94 (31.0)28 (37.8)54 (25.4)
       Prior aortic surgery12 (4.0)7 (9.5)4 (1.9)
      Preoperative characteristics
       Transferred from outside facility176 (58.1)61 (82.4)102 (47.9)
       Preoperative heart rate >100 bpm71 (23.4)15 (20.1)47 (22.1)
       Systolic blood pressure <70 mm Hg118 (38.9)32 (43.2)75 (35.2)
       Creatinine >2.0 mg/dL67 (22.1)20 (27.0)42 (19.7)
       Preoperative pH < 7.271 (23.4)12 (16.2)52 (24.4)
       Preoperative loss of consciousness90 (29.7)23 (31.1)58 (27.2)
       Preoperative cardiac arrest44 (14.5)6 (8.1)37 (17.4)
      rEVAR, Ruptured endovascular aneurysm repair; rOR, ruptured open repair; SBP, systolic blood pressure.
      Throughout the study period, the majority of patients were repaired with open repair (70%). However, after the implementation of an “EVAR first” protocol, the majority of patients were repaired with rEVAR (53%). Of the 303 patients who presented with rAAA, 236 had preoperative computed tomography scans available. The average aneurysm size was 8.2 cm, and the majority (67%) were candidates for rEVAR on retrospective review by a single surgeon. Of the patients repaired with rEVAR, the average procedure time was 2 hours and 4 minutes, and 28% were dependent on an aortic occlusion balloon. The average rEVAR required 63 mL of contrast material and 19.6 minutes of fluoroscopy time. The average neck length was 23 mm. Of the open repairs, the average procedure time was 3 hours and 55 minutes with an average of 4.2 L of blood loss (Table II).
      Table IIAnatomic and procedural characteristics
      Anatomic characteristics
       Preoperative CT scan available236 (77.9)
       Average aneurysm size, cm8.27
       EVAR candidate158 (67.0)
      Endovascular repair74 (24.4)
       Procedure time, hours:minutes2:04
       Local anesthesia only31 (41.9)
       Heparin given43 (58.1)
       EBL, mL753
       Contrast material, mL63.1
       Fluoroscopy time, minutes19.6
       Average neck length, mm23.0
       Aortic occlusion balloon dependent21 (28.4)
      Open repair213 (70.3)
       Procedure time, hours:minutes3:55
       Heparin given95 (44.6)
       EBL, mL4173
      No operative repair16 (5.3)
      CT, Computed tomography; EBL, estimated blood loss; EVAR, endovascular aneurysm repair.
      Categorical variables are presented as number (%).
      There were 154 patients alive 30 days after rAAA repair, yielding an overall 30-day mortality of 49%. There were no single variables that were 100% predictive of mortality on univariate analysis (Table III). The multivariate logistic regression yielded four variables predictive of mortality: age >76 years (OR, 2.11; confidence interval [CI]. 1.47-4.97; P = .011), creatinine concentration >2.0 mg/dL (OR, 3.66; CI, 1.85-7.24; P < .001), pH <7.2 (OR, 2.58; CI, 1.27-5.24; P = .009), and SBP ever <70 mm Hg (OR, 2.70; CI, 1.46-4.97; P = .002; Table III).
      Table IIIPredictors of 30-day mortality
      Univariate analysis
      VariableOR95% CIP value
      Age >76 years1.231.09-1.38<.0001
      Creatinine concentration >2.0 mg/dL1.351.18-1.55<.0001
      SBP ever <70 mm Hg1.351.20-1.51<.0001
      pH <7.21.371.20-1.57<.0001
      Multivariate analysis
      VariableOR95% CIP value
      Age >76 years2.111.47-4.97.011
      Creatinine concentration >2.0 mg/dL3.661.85-7.24<.001
      SBP ever <70 mm Hg2.701.46-4.97.002
      pH <7.22.581.27-5.24.009
      CI, Confidence interval; OR, odds ratio; SBP, systolic blood pressure.
      The Harborview Medical Center (HMC) preoperative rAAA mortality risk score (range, 0-4) was calculated for each patient in the cohort by assigning 1 point for each of the predictors of 30-day mortality (Table IV). Table V shows the distribution of patients according to the HMC preoperative rAAA mortality risk score. There was a significant mortality benefit for rEVAR, with only 7% 30-day mortality with an HMC preoperative rAAA mortality risk score of 1, which was maintained across the range of scores. Whereas a score of 3 yielded 70% 30-day mortality after rEVAR, it predicted 82% 30-day mortality after rOR. A score of 4 yielded 100% 30-day mortality in all patients, although there were no patients in our cohort with a score of 4 who underwent endovascular repair (Table VI; Fig 3).
      Table IVHarborview Medical Center (HMC) preoperative ruptured abdominal aortic aneurysm (rAAA) mortality risk score
      VariableORPoints
      Age >76 years2.111 point
      Creatinine concentration >2.0 mg/dL3.661 point
      SBP ever <70 mm Hg2.701 point
      pH <7.22.581 point
      OR, Odds ratio; SBP, systolic blood pressure.
      Table VDistribution according to Harborview Medical Center (HMC) preoperative risk score
      Preoperative risk score01234
      Total cohort
       Deaths, No. (%)18 (27)18 (22)48 (70)25 (80)5 (100)
       No. of patients628370325
      Table VIThirty-day mortality predicted by Harborview Medical Center (HMC) preoperative risk score
      Preoperative risk score0 points1 point2 points3 points4 points
      All patients, %29227080100
      rEVAR, %2873770
      rOR repair, %30308082100
      rEVAR, Ruptured endovascular aneurysm repair; rOR, ruptured open repair.
      Figure thumbnail gr3
      Fig 3Mortality predicted by Harborview Medical Center (HMC) preoperative risk score. EVAR, Endovascular aneurysm repair.

      Discussion

      Prediction of mortality after rAAA repair is important for many reasons, most important of which is the ability to guide patient care. There has been significant improvement in mortality after rAAA repair in the last 15 years after implementation of an endovascular first strategy,
      • Starnes B.W.
      • Quiroga E.E.
      • Hutter C.C.
      • Tran N.T.
      • Hatsukami T.T.
      • Meissner M.M.
      • et al.
      Management of ruptured abdominal aortic aneurysm in the endovascular era.
      • Mayer D.
      • Aeschbacher S.
      • Pfammatter T.
      Complete replacement of open repair for ruptured abdominal aortic aneurysms by endovascular aneurysm repair. A two-center 14-year experience.
      rAAA multidisciplinary care protocols,
      • Mehta M.
      • Taggert J.
      • Darling R.C.
      • Chang B.B.
      • Kreienberg P.B.
      • Paty P.S.
      • et al.
      Establishing a protocol for endovascular treatment of ruptured abdominal aortic aneurysms: outcomes of a prospective analysis.
      • Moore R.
      • Nutley M.
      • Cina C.S.
      • Motamedi M.
      • Faris P.
      • Abuznadah W.
      Improved survival after introduction of an emergency endovascular therapy protocol for ruptured abdominal aortic aneurysms.
      • Oyague K.S.
      • Mubarak O.A.
      • Nowak L.R.
      • Gainer J.G.
      • Rehring T.F.
      • O'Brien M.M.
      • et al.
      Endovascular repair of ruptured and symptomatic abdominal aortic aneurysms using a structured protocol in a community teaching hospital.
      and regionalization of specialized vascular care.
      • Hill J.S.
      • McPhee J.T.
      • Messina L.M.
      • Ciocca R.G.
      • Eslami M.H.
      Regionalization of abdominal aortic aneurysm repair: evidence of a shift to high-volume centers in the endovascular era.
      • McPhee J.
      • Eslami M.H.
      • Arous E.J.
      • Messina L.M.
      • Schanzer A.
      Endovascular treatment of ruptured abdominal aortic aneurysms in the United States (2001-2006): a significant survival benefit over open repair is independently associated with increased institutional volume.
      Despite these advancements, there are still patients who will die of their rAAA. The ability to accurately predict 30-day mortality before a patient is transferred to a tertiary care facility may help allocate resources and mitigate risk to patients and providers. Preoperative prediction of 30-day mortality will also help guide discussions with patients and their families and may help with the decision to move toward comfort care vs going to the operating room.
      A risk score in treating patients with AAA is not a novel concept. The GAS was introduced in 1994. It is calculated on the basis of the patient's comorbidities as a sum of the following: age + (7 points for myocardial disease) + (10 points for cerebrovascular disease) + (14 points for renal disease). In patients presenting in shock, 17 points are added. It was designed to predict perioperative mortality and morbidity after open repair.
      • Samy A.K.
      • Murray G.
      • MacBain G.
      Glasgow aneurysm score.
      Whereas the variables in this model are easily obtained, the model was created well before the endovascular era when patients were undergoing only open repair. In the modern era, many patients who are undergoing open repair often have challenging anatomy that precludes them from undergoing EVAR. The GAS has been validated more recently for open repair and EVAR in the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial as well as in the European Collaborators on Stent-graft Techniques for Abdominal Aortic aneurysm Repair (EUROSTAR) trial. To perform the analysis in the DREAM trial patients, the GAS was modified to not include the 17 points attached to shock patients as these were completely elective cases.
      • Baas A.F.
      • Janssen K.J.
      • Prinssen M.
      • Buskens E.
      • Blankenstijn J.D.
      The Glasgow Aneurysm Score as a tool to predict 30-day and 2-year mortality in the patients from the Dutch Randomized Endovascular Aneurysm Management Trial.
      Again, validating the GAS in the elective EVAR population does not correlate with patients with rAAA who are eligible for EVAR.
      The Hardman index was developed in 1996
      • Hardman D.T.
      • Fisher C.M.
      • Patel M.I.
      • Neale M.
      • Chambers J.
      • Lane R.
      • et al.
      Ruptured abdominal aortic aneurysms: who should be offered surgery?.
      and includes five variables: age, level of consciousness, hemoglobin concentration, renal function, and ischemia noted on electrocardiography. It was originally proposed that no surgery should be offered to those patients with three or more risk factors. Although it is relatively simple to obtain and to calculate, it has been used only in Europe, where variability exists in treatment of rAAA and who should be offered repair.
      • Karkos C.D.
      • Karamanos D.
      • Papzoglou K.O.
      • Kantas A.S.
      • Theochari E.G.
      • Kamparoudis A.G.
      • et al.
      Usefulness of the Hardman index in predicting outcome for endovascular repair of ruptured abdominal aortic aneurysms.
      More recently, the VSGNE derived an rAAA scoring system based on four variables (age, preoperative cardiac arrest, loss of consciousness, and suprarenal aortic clamp) that is designed to predict mortality after open repair.
      • Robinson W.P.
      • Schanzer A.
      • Li Y.
      • Goodney P.P.
      • Nolan B.W.
      • Eslami M.H.
      • et al.
      Derivation and validation of a practical risk score for prediction of mortality after open repair of ruptured abdominal aortic aneurysms in a U.S. regional cohort and comparison to existing scoring systems.
      Although the scoring system is simplistic, it again is for open repair only and does suffer from the heterogeneity of the various centers and the inability to derive granular data from these large database studies. In addition, it requires intraoperative variables, which precludes its use in the preoperative setting.
      Validation of a preoperative clinical risk tool for rAAA repair in the endovascular era will help standardize risk across patients without the confounding of open vs endovascular repair.
      • Robinson W.P.
      • Schanzer A.
      • Li Y.
      • Goodney P.P.
      • Nolan B.W.
      • Eslami M.H.
      • et al.
      Derivation and validation of a practical risk score for prediction of mortality after open repair of ruptured abdominal aortic aneurysms in a U.S. regional cohort and comparison to existing scoring systems.
      Many algorithms have been proposed for the prediction of mortality after repair of rAAA in both the open and endovascular era. However, many of the previously described scoring systems are not valid in the endovascular era or do not accurately predict those at highest risk. Interestingly, 15 of our subjects were EVAR candidates but underwent open repair. The reasons for this were that not all of our vascular surgeons were able to offer rEVAR when on call, and an endovascular surgeon was not always available early in our experience. That has changed now, when 100% of our surgeons are comfortable with EVAR.
      The HMC preoperative rAAA mortality risk score is the first algorithm described that accurately predicts mortality using only preoperative variables that are readily measured in minutes at the bedside with i-STAT technology (Abbott Point of Care, Princeton, NJ). The factors of age, creatinine concentration, pH, and SBP <70 mm Hg are items that the referring provider at an outside hospital can easily communicate. Our response to the referring provider that patients in our single-institution study suffered 22% mortality with 1 point, 69% mortality with 2 points, 80% mortality with 3 points, and 100% mortality with 4 points is usually well received, and in those patients with three or four risk factors, the physicians now have data to tell the patient and the patients' families that transfer may be futile. As we have patients transferred from hospitals throughout the Pacific Northwest and an excellent transport service, the option of not operating on a patient with an 80% to 100% likelihood of mortality allows the family to spend time with the patient and to initiate comfort care measures vs the potential of dying during transport while the family is desperately driving to the hospital. In addition to the social implications, the cost of transport from these hospitals may be avoided as well as the operating room costs that occur when the family is presented with the bill after their loved one has died.
      Our study does have limitations. The HMC score was developed during a period of changing paradigms in the treatment of AAAs. Before 2007, all rAAAs were treated with open repair, whereas after this period, the majority were treated with EVAR. Although EVAR showed a benefit in the modern era, patients undergoing an open repair after 2007 are likely to represent higher risk anatomy, such as juxtarenal aneurysms. Our score is reflective of our institution and has not been validated at other institutions. Whereas the recognition of rAAA with the need to have a “rupture protocol” has been extremely successful at our hospital, it may not be applicable to institutions that see a low volume of rAAAs. In addition, the majority of our patients were transferred from an outside hospital, and the mere fact that they survived transport may bias the results. However, all of these patients were treated at a single institution that is deemed high volume for this disease, and all our data were obtained from this population and not saturated with results from other institutions, allowing us to believe strongly that this model works at our institution.

      Conclusions

      The HMC preoperative rAAA risk score is the only practical risk score based solely on preoperative variables readily assessed at the bedside and allows accurate prediction of 30-day mortality after repair of rAAAs. It also has a direct impact on clinical decision-making by adding prognostic information to the decision to transfer patients to tertiary care centers and aiding in preoperative discussions with patients and their families.

      Author contributions

      Conception and design: BG, PD, NS, BS
      Analysis and interpretation: BG, PD, SD, NT, EQ, NS, BS
      Data collection: BG, SD, NT, EQ, NS, BS
      Writing the article: BG, NS, BS
      Critical revision of the article: BG, PD, SD, NT, EQ, NS, BS
      Final approval of the article: BG, PD, SD, NT, EQ, NS, BS
      Statistical analysis: PD
      Obtained funding: Not applicable
      Overall responsibility: BG

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      Linked Article

      • Correction
        Journal of Vascular SurgeryVol. 68Issue 5
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          In the October 2018 issue of the Journal of Vascular Surgery, the corresponding author of the article “Preoperative risk score for the prediction of mortality after repair of ruptured abdominal aortic aneurysms” (J Vasc Surg 2018;68:991-7) should be Dr Benjamin Ware Starnes, Department of Surgery, University of Washington, 325 Ninth Ave, Box 359796, Seattle, WA 98104 (e-mail: [email protected] ).
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