Epidemiology of ruptured abdominal aortic aneurysms in a well-defined Norwegian population with trends in incidence, intervention rate, and mortality Andreas Reite, MD,a Kjetil Søreide, MD, PhD,b,e Christian Lycke Ellingsen, MD,c,f Jan Terje Kvaløy, PhD,d,g and Morten Vetrhus, MD, PhD,a Stavanger, Bergen, and Oslo, Norway Objective: Ruptured infrarenal abdominal aortic aneurysms (rAAAs) represent both a life-threatening emergency for the affected patient and a considerable health burden globally. The aim of this study was to investigate the contemporary epidemiology of rAAA in a defined Norwegian population for which both hospital and autopsy data were available. Methods: This was a retrospective, single-center population-based study of rAAA. The study includes all consecutively diagnosed prehospital and in-hospital cases of rAAA in the catchment area of Stavanger University Hospital between January 2000 and December 2012. Incidence and mortality rates (crude and adjusted) were calculated using national demographic data. Results: A total of 216 patients with primary rAAA were identified. The adjusted incidence rate for the study period was 11.0 per 100,000 per year (95% confidence interval [CI], 9.6-12.5). Twenty patients died out of the hospital, and 144 of the 196 patients (73%) admitted to the hospital underwent surgery. The intervention rate varied from 48% to 81% during the study period. The adjusted mortality rate was 7.5 per 100,000 per year (95% CI, 6.3-8.8). No differences in the incidence and mortality rates were found in comparing early and late periods. The 90-day standardized mortality ratio for the study period was 37.2 (95% CI, 31.6-43.7). The overall 90-day mortality was 68% (146 of 216 persons) and 51% (74 of 144 persons) for the patients treated for rAAA. Conclusions: We found a stable incidence and mortality rate during a decade. The prehospital death rate was lower (9%), the intervention rate (73%) higher, and the total mortality (68%) lower than in most other studies. Geographic and regional differences may influence the epidemiologic description of rAAA and hence should be taken into consideration in comparing outcomes for in-hospital mortality and intervention rates. (J Vasc Surg 2015;-:1-7.)
Abdominal aortic aneurysm (AAA) represents a considerable global health burden and the second most frequent cause of death from all emergency surgical conditions.1 Prevalence of AAA increases with age, and risk of rupture increases with increasing size of the aneurysm. Whereas elective surgery has a mortality usually reported 30 years of age). Adjusted incidence rates and genderspecific adjusted incidence rates are calculated using the crude rates and adjusting for gender and age vs the total Norwegian population. The numbers are provided by Statistics Norway. Likewise, from the number of deaths, crude and adjusted mortality rates were calculated. The standardized mortality ratio of rAAA is the number of deaths within 90 days of admission, divided by the number of expected deaths in a general population with the same age and gender distribution. Statistical analysis. The analyses were performed with the Statistical Package for Social Sciences (v 22; IBM, Armonk, NY) and R 3.1.0 (www.r-project.org). The c2 test or Fisher exact test was used to test for differences in categorical variables between groups, and the MannWhitney test was used for continuous variables. Poisson regression analysis was used to compare incidence and mortality early and late in the study period. All tests are two sided, and P values < .050 were regarded as statistically significant. RESULTS Patient characteristics. Between 2000 and 2012, a total of 223 patients with rAAA were identified; 7 of these were secondary aneurysms and were excluded from the analyses. Of the 216 patients with primary rAAA, 196 (91%) were admitted to the hospital. The remaining 20 (9%) died out of the hospital and were diagnosed after a clinical or forensic autopsy. The patient characteristics for the early and latter part of the study period are given in Table I. The majority (79%) of the patients were men. The median age was 77 years in men and 87 years in women (P < .001). Of the 196 patients who were admitted to the hospital, 186 (95%) had symptoms of rAAA. The remaining 10 patients were primarily admitted because of unrelated causes, including pneumonia, stroke, pertrochanteric fracture, hematuria, and constipation, and developed symptoms of rAAA after a median of 7 days (range, 1-30 days) in the hospital. Isolated aortic aneurysms had the highest prevalence (84%); aortoiliac aneurysms accounted for 13%. In five cases (2%), the precise extent of the aneurysm was not stated. The median diameter of the aneurysms was 75 mm (range, 46-130 mm).
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Table I. Patient characteristics during the two time periods Time period Variable
Early period (2000-2006) (n ¼ 114)
Late period (2007-2012) (n ¼ 102)
P value
80 (45-99) 5 (1-336)
79 (57-96) 4 (1-336)
.977 .093
91 (80) 23 (20)
79 (78) 23 (22)
.671
97 (85) 14 (12) 75 (46-130)
85 (83) 15 (15) 74 (50-120)
.615
60 3 10 16 8 75
41 10 13 15 6 71
.118 .040 .290 .787 .798 .549
Median age, years (range) Median duration of symptoms, hours (range) Sex Male Female Type of rAAA (5 cases missing) Aortic Aortoiliac Median aneurysm size, mm (range) (48 cases missing) Comorbidities (8 cases missing) Heart disease Renal failure Pulmonary disease Cerebrovascular disease Diabetes mellitus 90-day mortality
(52) (3) (9) (14) (7) (66)
(40) (10) (13) (15) (6) (70)
.923
rAAA, Ruptured abdominal aortic aneurysm. Data are presented as number (%) unless otherwise indicated.
A substantial number of the patients had a history of heart disease, but no statistical differences were found in the number and rates of comorbidity between early (2000-2006) and late (2007-2012) periods of the study. The only exception was the prevalence of renal disease, which was significantly higher in the latter period. Altogether, 44 of the 216 patients (20%) had a known AAA. The majority had been considered unfit for surgery (17 patients) or did not want an operation (10 patients). The others were waiting for an elective operation (two patients), were lost to follow-up (six patients), had not been referred to a vascular surgeon (seven patients), or had been assessed at a different hospital (two patients). Crude and adjusted incidence trends. The crude incidence rate for rAAA for the whole study period was 9.5 per 100,000 per year in persons >30 years, with the highest incidence registered in 2007 (13.0) and the lowest in 2011 (6.2). This variation is not significant. The adjusted incidence rate of rAAA for the whole period was 11.0 per 100,000 per year (95% confidence interval [CI], 9.6-12.5), and as for the crude rates, the highest adjusted incidence rate was registered in 2007 (15.0; 95% CI, 9.522.6) and the lowest in 2011 (7.3; 95% CI, 3.8-12.8) (Fig 1). The adjusted incidence rates stratified by gender did not show any significant change over time (Fig 2). The adjusted incidence rate for men (17.6; 95% CI, 15.020.4) was significantly higher than that for women (4.7; 95% CI, 3.6-6.2). No significant differences (P ¼ .555) in incidence rate were found between early (2000-2006) and late (20072012) periods of the study. Intervention rate. Altogether, 144 of the 196 patients (73%) who were admitted to the hospital underwent surgery, of whom only one had an endovascular aneurysm
Fig 1. Adjusted incidence rate.
repair (EVAR). Of the 143 patients who had an open operation, 16 patients (11%) died of exsanguination before a graft was put in, 97 patients (68%) had a tube graft, and 30 patients (21%) had a bifurcated graft. Thus, 52 admitted patients did not have an intervention (Table II; Fig 3). A majority of these patients were dead or moribund at the time of diagnosis (five were dead on arrival, six had a cardiac arrest in the emergency department, and three were agonal at the time of diagnosis) or were admitted to other departments and died without rAAA being suspected and diagnosed first on autopsy. Crude and adjusted mortality trends. The crude and adjusted mortality rates showed some variation over time,
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Fig 3. Intervention rate in admitted patients.
Fig 2. Adjusted incidence rate by gender.
Table II. Site and mode of death in patients with fatal ruptured abdominal aortic aneurysm (rAAA) All deaths Prehospital deaths In-hospital deaths Did not want operation Considered unfit for surgery Metastatic disease Agonal at time of diagnosis Diagnosed on autopsy Perioperative deaths
No. (%) (N ¼ 146) 20 (14) 126 (86) 10 15 1 14 12 77
but not significantly (Figs 4 and 5). The crude mortality rate for the study period was 6.4 per 100,000 persons per year, and the corresponding adjusted mortality rate was 7.5 (95% CI, 6.3-8.8). When comparing the early and late periods of the study, we found no statistically significant difference (P ¼ .884) in mortality rate. The 90-day standardized mortality ratio for the study period was 37.2 (95% CI, 31.6-43.7) and, when split for gender, 39.3 (95% CI, 32.6-47.5) in men and 32.0 (95% CI, 23.2-44.2) in women (Fig 6). The 90-day total mortality was 68% (146 of 216 persons), somewhat higher than what was observed within 30 days (138 deaths; 64%). A total of 144 patients (67%) had an operation. The postoperative 90-day mortality was 51% (74 of 144), 57% (12 of 21) in women and 50% in men (62 of 123) (P ¼ .568). DISCUSSION We found the adjusted incidence rate for the study period to be 11.0 per 100,000 per year (95% CI, 9.612.5). Although considerable disparities in incidence rate
Fig 4. Crude mortality rate.
have been reported within Norway,6 the findings correspond well with a fairly recent Scandinavian report.15 SUH has a care pathway for aneurysms. If a patient is admitted with suspected rAAA or rAAA is expected after the patient has been assessed in the emergency department, the vascular surgeon on call and the anesthesiologist on site will be summoned. The radiologist is on site and will perform ultrasound in the emergency department in unstable patients; stable patients will be taken for CT examination. If recent renal function test results are not available at the time of CT, the first run will be without contrast material; a subsequent run with contrast material will be performed at the discretion of the attending vascular surgeon. A dedicated vascular operation room is available aroundthe-clock. As of today, SUH has no hybrid suites. However, the service provided is devoid of referral bias and diagnostic delay, as the hospital covers all patients in the region for a centralized, one-stop, protocol-committed care for all vascular emergencies.16,17 Altogether, 27% (52 of 196) of the patients who were admitted to the hospital did not have an intervention.
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Fig 5. Adjusted mortality rate.
Notably, most previous studies report a substantially higher nonintervention rate.15,16 Lower nonintervention rates are rarely reported, with only two previous studies reporting numbers below 20% (19% and 9%, respectively),18,19 and neither of these studies published the clinical or forensic autopsy rates in the relevant catchment areas. In our study, a substantial portion of the “nonintervention” patients were diagnosed post mortem (n ¼ 12) or were moribund or agonal (n ¼ 14) at the time of diagnosis. Thus, excluding these 26 patients, the nonintervention rate may be considered at 15% (26 of 170 eligible for surgery), and among these 26 patients alive and potentially eligible for intervention, the decision to not intervene was based on the patient’s own expressed wish and decision in 38% (10 of 26). High autopsy rates are necessary to obtain valid rAAA rates. A few dated papers examining rAAA in the 1970s and 1980s reported very high autopsy rates of 61% to 85%20,21 and found that up to 40% of patients with rAAA died outside of the hospital. During the observation period, the rate of autopsy of in-hospital deaths in SUH varied from 28% to 19%, whereas the rate of forensic autopsies was stable throughout the period (41 to 47 of 100,000 per year). Forensic autopsies may not be performed in elderly patients in a care institution or for patients with known terminal disease. This may introduce a bias regarding the autopsy finding; however, we believe this to be of little clinical relevance as such cases are unlikely to be suitable for intervention. In our study, 9% died before hospitalization. Autopsy rates of 60% to 80% cannot be matched today with a global decline in autopsy rates; thus, it is reasonable to assume that newer studies systematically underestimate the incidence of rAAA. On the other hand, one may theorize that the threshold for seeking medical help is lower and the availability of health care services including cross-sectional body imaging is better and more
Reite et al 5
Fig 6. The 90-day standardized mortality ratio stratified by gender.
prevalent in the population. The emergency medical services serving SUH have reported high survival rates and short response time after out-of-hospital arrest in previous studies.22 Efficient emergency medical services may be a contributing factor in the low numbers of prehospital deaths. The overall mortality (68%) in the current study is in contrast to the findings of a recent meta-analysis of population-based mortality of rAAA analyzing 24 papers published since 1977, which reported a pooled mortality of 81% (95% CI, 78-83).11 Meta-analyses found that the mortality of rAAA has improved during the last few decades.11,23 We did not find any change in mortality between early and late time periods in the current study. Most papers on rAAA and survival report only inhospital mortality or include a selected population.24,25 Overall mortality in rAAA is determined by the number of patients dying in the prehospital phase, the number of admitted patients not having an intervention, and the perioperative mortality in those undergoing surgery. Previous studies report widely divergent results on perioperative mortality. Studies with the better results (ie, mortality 40%) when nonintervention rates are reported.15,16,19 In our series, the operative mortality was 51%. One may speculate that there is an inverse relationship between low nonintervention rates and high perioperative mortality. This needs to be considered in evaluating studies from different regions and of differing outcomes. Whereas the strict population-based design with excellent coverage for prehospital and in-hospital deaths from rAAA is among the strengths of this study, some limitations
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deserve to be mentioned. The time period covered by our study may be too short and may possibly involve too few patients to demonstrate any significant trends in the incidence of rAAA. No significant differences can be found in the time plots; the CIs are overlapping. Recent papers report that the incidence of AAA is waning,30 but because of lag, this trend is only slowly starting to affect the incidence of rAAA.15,31,32 A considerable majority (79%) of the patients were men; but contrary to what others have reported, the few women did not have significantly higher perioperative mortality than the men. Other authors report a gender difference in mortality and argue that although women presenting with rAAA are significantly older than men, the difference in mortality seems to persist even when adjusted for age.33 Some have suggested that one contributing factor may be that cardiovascular disease is underdiagnosed in many women.34 This and other similar studies show the limitations of open repair of rAAA (ie, high mortality). The study is not designed to address the questions of whether a screening program or EVAR may change the risk of rupture or mortality in rAAA, but we find it pertinent to address these issues briefly. Several studies have shown that screening programs reduce the risk of aneurysmrelated deaths.35 Several larger studies demonstrate better survival with increased use of EVAR,36,37 although the smaller randomized clinical trials have failed to find a survival benefit.37 During the study period, we established EVAR for elective repair; but as of today, only one rAAA has been treated by EVAR. Taking up EVAR in rAAA is dependent on local expertise and facilities and logistics. In our case, the main obstacle has been and still is funding of a hybrid laboratory. We find the angiography suite unsuitable for EVAR in rAAA as some patients will need an open operation or open adjuncts to EVAR. CONCLUSIONS The overall mortality of rAAA in this study was 68%. This is lower than in most other studies and metaanalyses. The difference is not due to lower perioperative mortality (51%), but few patients died in the prehospital (9%) phase, and the intervention rate was high (73%) in patients admitted alive. There was no significant difference in incidence or mortality between early and late in the 13-year study period. A considerable majority of patients were men (79%), but the few women did not have a significantly higher postoperative mortality than men. AUTHOR CONTRIBUTIONS Conception and design: AR, KS, MV Analysis and interpretation: AR, KS, JK, MV Data collection: AR, CE, MV Writing the article: AR, KS, CE, JK, MV Critical revision of the article: AR, KS, CE, JK, MV Final approval of the article: AR, KS, CE, JK, MV
Statistical analysis: JK, MV Obtained funding: Not applicable Overall responsibility: MV REFERENCES 1. Stewart B, Khanduri P, McCord C, Ohene-Yeboah M, Uranues S, Vega Rivera F, et al. Global disease burden of conditions requiring emergency surgery. Br J Surg 2014;101:e9-22. 2. Mani K, Lees T, Beiles B, Jensen LP, Venermo M, Simo G, et al. Treatment of abdominal aortic aneurysm in nine countries 2005-2009: a vascunet report. Eur J Vasc Endovasc Surg 2011;42:598-607. 3. Lo RC, Bensley RP, Hamdan AD, Wyers M, Adams JE, Schermerhorn ML. Gender differences in abdominal aortic aneurysm presentation, repair, and mortality in the Vascular Study Group of New England. J Vasc Surg 2013;57:1261-8. 1268.e1-5. 4. Mani K, Bjorck M, Wanhainen A. Changes in the management of infrarenal abdominal aortic aneurysm disease in Sweden. Br J Surg 2013;100:638-44. 5. Schermerhorn ML, Bensley RP, Giles KA, Hurks R, O’Malley AJ, Cotterill P, et al. Changes in abdominal aortic aneurysm rupture and short-term mortality, 1995-2008: a retrospective observational study. Ann Surg 2012;256:651-8. 6. Brattheim BJ, Eikemo TA, Altreuther M, Landmark AD, Faxvaag A. Regional disparities in incidence, handling and outcomes of patients with symptomatic and ruptured abdominal aortic aneurysms in Norway. Eur J Vasc Endovasc Surg 2012;44:267-72. 7. Karthikesalingam A, Holt PJ, Vidal-Diez A, Ozdemir BA, Poloniecki JD, Hinchliffe RJ, et al. Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA. Lancet 2014;383:963-9. 8. Hadjibashi AA, Mirocha J, Cossman DV, Gewertz BL. Decreases in diameters of treated abdominal aortic aneurysms and reduction in rupture rate. JAMA Surg 2013;148:72-5. 9. Hadjibashi AA, Ng T, Mirocha J, Cossman D, Gewertz B. Reduction in ruptured aortic aneurysms is not due to increases in endovascular repairs. Am Surg 2011;77:1395-8. 10. Lee AM, Chaikof EL. Is the abdominal aortic aneurysm rupture rate decreasing? Adv Surg 2013;47:271-86. 11. Reimerink JJ, van der Laan MJ, Koelemay MJ, Balm R, Legemate DA. Systematic review and meta-analysis of populationbased mortality from ruptured abdominal aortic aneurysm. Br J Surg 2013;100:1405-13. 12. Thorsen K, Soreide JA, Kvaloy JT, Glomsaker T, Soreide K. Epidemiology of perforated peptic ulcer: age- and gender-adjusted analysis of incidence and mortality. World J Gastroenterol 2013;19:347-54. 13. Meling T, Harboe K, Soreide K. Incidence of traumatic long-bone fractures requiring in-hospital management: a prospective age- and gender-specific analysis of 4890 fractures. Injury 2009;40:1212-9. 14. Johnston KW, Rutherford RB, Tilson MD, Shah DM, Hollier L, Stanley JC. Suggested standards for reporting on arterial aneurysms. Subcommittee on Reporting Standards for Arterial Aneurysms, Ad Hoc Committee on Reporting Standards, Society for Vascular Surgery and North American Chapter, International Society for Cardiovascular Surgery. J Vasc Surg 1991;13:452-8. 15. Acosta S, Ogren M, Bengtsson H, Bergqvist D, Lindblad B, Zdanowski Z. Increasing incidence of ruptured abdominal aortic aneurysm: a population-based study. J Vasc Surg 2006;44:237-43. 16. Hafez H, Owen LW, Lorimer CF, Bajwa A. Advantage of a one-stop referral and management service for ruptured abdominal aortic aneurysms. Br J Surg 2009;96:1416-21. 17. Laukontaus SJ, Aho PS, Pettila V, Alback A, Kantonen I, Railo M, et al. Decrease of mortality of ruptured abdominal aortic aneurysm after centralization and in-hospital quality improvement of vascular service. Ann Vasc Surg 2007;21:580-5. 18. Mealy K, Salman A. The true incidence of ruptured abdominal aortic aneurysms. Eur J Vasc Surg 1988;2:405-8. 19. Qureshi NA, Rehman A, Slater N, Moss E, Shiralkar S, Patel RT, et al. Abdominal aortic aneurysm surgery in a district general hospital: a 15-years experience. Ann Vasc Surg 2007;21:749-53.
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20. Bengtsson H, Bergqvist D. Ruptured abdominal aortic aneurysm: a population-based study. J Vasc Surg 1993;18:74-80. 21. Johansson G, Swedenborg J. Ruptured abdominal aortic aneurysms: a study of incidence and mortality. Br J Surg 1986;73:101-3. 22. Lindner TW, Soreide E, Nilsen OB, Torunn MW, Lossius HM. Good outcome in every fourth resuscitation attempt is achievabledan Utstein template report from the Stavanger region. Resuscitation 2011;82: 1508-13. 23. Bown MJ, Sutton AJ, Bell PR, Sayers RD. A meta-analysis of 50 years of ruptured abdominal aortic aneurysm repair. Br J Surg 2002;89: 714-30. 24. Visser P, Akkersdijk GJ, Blankensteijn JD. In-hospital operative mortality of ruptured abdominal aortic aneurysm: a population-based analysis of 5593 patients in The Netherlands over a 10-year period. Eur J Vasc Endovasc Surg 2005;30:359-64. 25. Alexander S, Bosch JL, Hendriks JM, Visser JJ, Van Sambeek MR. The 30-day mortality of ruptured abdominal aortic aneurysms: influence of gender, age, diameter and comorbidities. J Cardiovasc Surg (Torino) 2008;49:633-7. 26. Gupta PK, Ramanan B, Engelbert TL, Tefera G, Hoch JR, Kent KC. A comparison of open surgery versus endovascular repair of unstable ruptured abdominal aortic aneurysms. J Vasc Surg 2014;60:1439-45. 27. Hawkins AT, Smith AD, Schaumeier MJ, de Vos MS, Hevelone ND, Nguyen LL. The effect of surgeon specialization on outcomes after ruptured abdominal aortic aneurysm repair. J Vasc Surg 2014;60:590-6. 28. Noorani A, Page A, Walsh SR, Varty K, Hayes PD, Boyle JR. Mid-term outcomes following emergency endovascular aortic aneurysm repair for ruptured abdominal aortic aneurysms. Eur J Vasc Endovasc Surg 2012;43:382-5. 29. Veith FJ, Lachat M, Mayer D, Malina M, Holst J, Mehta M, et al. Collected world and single center experience with endovascular
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treatment of ruptured abdominal aortic aneurysms. Ann Surg 2009;250:818-24. Svensjo S, Mani K, Bjorck M, Lundkvist J, Wanhainen A. Screening for abdominal aortic aneurysm in 65-year-old men remains cost-effective with contemporary epidemiology and management. Eur J Vasc Endovasc Surg 2014;47:357-65. Lindholt JS, Sogaard R, Laustsen J. Prognosis of ruptured abdominal aortic aneurysms in Denmark from 1994-2008. Clin Epidemiol 2012;4:111-3. Norman PE, Spilsbury K, Semmens JB. Falling rates of hospitalization and mortality from abdominal aortic aneurysms in Australia. J Vasc Surg 2011;53:274-7. Mureebe L, Egorova N, McKinsey JF, Kent KC. Gender trends in the repair of ruptured abdominal aortic aneurysms and outcomes. J Vasc Surg 2010;51:9S-13S. Grootenboer N, van Sambeek MR, Arends LR, Hendriks JM, Hunink MG, Bosch JL. Systematic review and meta-analysis of sex differences in outcome after intervention for abdominal aortic aneurysm. Br J Surg 2010;97:1169-79. Cosford PA, Leng GC. Screening for abdominal aortic aneurysm. Cochrane Database Syst Rev 2007;2:CD002945. Dua A, Kuy S, Lee CJ, Upchurch GR Jr, Desai SS. Epidemiology of aortic aneurysm repair in the United States from 2000 to 2010. J Vasc Surg 2014;59:1512-7. van Beek SC, Conijn AP, Koelemay MJ, Balm R. Editor’s Choiced Endovascular aneurysm repair versus open repair for patients with a ruptured abdominal aortic aneurysm: a systematic review and metaanalysis of short-term survival. Eur J Vasc Endovasc Surg 2014;47: 593-602.
Submitted Oct 6, 2014; accepted Dec 18, 2014.
Abdominal aortic aneurysm (AAA) represents a considerable global health burden and the second most frequent cause of death from all emergency surgical conditions.1 Prevalence of AAA increases with age, and risk of rupture increases with increasing size of the aneurysm. Whereas elective surgery has a mortality usually reported 30 years of age). Adjusted incidence rates and genderspecific adjusted incidence rates are calculated using the crude rates and adjusting for gender and age vs the total Norwegian population. The numbers are provided by Statistics Norway. Likewise, from the number of deaths, crude and adjusted mortality rates were calculated. The standardized mortality ratio of rAAA is the number of deaths within 90 days of admission, divided by the number of expected deaths in a general population with the same age and gender distribution. Statistical analysis. The analyses were performed with the Statistical Package for Social Sciences (v 22; IBM, Armonk, NY) and R 3.1.0 (www.r-project.org). The c2 test or Fisher exact test was used to test for differences in categorical variables between groups, and the MannWhitney test was used for continuous variables. Poisson regression analysis was used to compare incidence and mortality early and late in the study period. All tests are two sided, and P values < .050 were regarded as statistically significant. RESULTS Patient characteristics. Between 2000 and 2012, a total of 223 patients with rAAA were identified; 7 of these were secondary aneurysms and were excluded from the analyses. Of the 216 patients with primary rAAA, 196 (91%) were admitted to the hospital. The remaining 20 (9%) died out of the hospital and were diagnosed after a clinical or forensic autopsy. The patient characteristics for the early and latter part of the study period are given in Table I. The majority (79%) of the patients were men. The median age was 77 years in men and 87 years in women (P < .001). Of the 196 patients who were admitted to the hospital, 186 (95%) had symptoms of rAAA. The remaining 10 patients were primarily admitted because of unrelated causes, including pneumonia, stroke, pertrochanteric fracture, hematuria, and constipation, and developed symptoms of rAAA after a median of 7 days (range, 1-30 days) in the hospital. Isolated aortic aneurysms had the highest prevalence (84%); aortoiliac aneurysms accounted for 13%. In five cases (2%), the precise extent of the aneurysm was not stated. The median diameter of the aneurysms was 75 mm (range, 46-130 mm).
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Table I. Patient characteristics during the two time periods Time period Variable
Early period (2000-2006) (n ¼ 114)
Late period (2007-2012) (n ¼ 102)
P value
80 (45-99) 5 (1-336)
79 (57-96) 4 (1-336)
.977 .093
91 (80) 23 (20)
79 (78) 23 (22)
.671
97 (85) 14 (12) 75 (46-130)
85 (83) 15 (15) 74 (50-120)
.615
60 3 10 16 8 75
41 10 13 15 6 71
.118 .040 .290 .787 .798 .549
Median age, years (range) Median duration of symptoms, hours (range) Sex Male Female Type of rAAA (5 cases missing) Aortic Aortoiliac Median aneurysm size, mm (range) (48 cases missing) Comorbidities (8 cases missing) Heart disease Renal failure Pulmonary disease Cerebrovascular disease Diabetes mellitus 90-day mortality
(52) (3) (9) (14) (7) (66)
(40) (10) (13) (15) (6) (70)
.923
rAAA, Ruptured abdominal aortic aneurysm. Data are presented as number (%) unless otherwise indicated.
A substantial number of the patients had a history of heart disease, but no statistical differences were found in the number and rates of comorbidity between early (2000-2006) and late (2007-2012) periods of the study. The only exception was the prevalence of renal disease, which was significantly higher in the latter period. Altogether, 44 of the 216 patients (20%) had a known AAA. The majority had been considered unfit for surgery (17 patients) or did not want an operation (10 patients). The others were waiting for an elective operation (two patients), were lost to follow-up (six patients), had not been referred to a vascular surgeon (seven patients), or had been assessed at a different hospital (two patients). Crude and adjusted incidence trends. The crude incidence rate for rAAA for the whole study period was 9.5 per 100,000 per year in persons >30 years, with the highest incidence registered in 2007 (13.0) and the lowest in 2011 (6.2). This variation is not significant. The adjusted incidence rate of rAAA for the whole period was 11.0 per 100,000 per year (95% confidence interval [CI], 9.6-12.5), and as for the crude rates, the highest adjusted incidence rate was registered in 2007 (15.0; 95% CI, 9.522.6) and the lowest in 2011 (7.3; 95% CI, 3.8-12.8) (Fig 1). The adjusted incidence rates stratified by gender did not show any significant change over time (Fig 2). The adjusted incidence rate for men (17.6; 95% CI, 15.020.4) was significantly higher than that for women (4.7; 95% CI, 3.6-6.2). No significant differences (P ¼ .555) in incidence rate were found between early (2000-2006) and late (20072012) periods of the study. Intervention rate. Altogether, 144 of the 196 patients (73%) who were admitted to the hospital underwent surgery, of whom only one had an endovascular aneurysm
Fig 1. Adjusted incidence rate.
repair (EVAR). Of the 143 patients who had an open operation, 16 patients (11%) died of exsanguination before a graft was put in, 97 patients (68%) had a tube graft, and 30 patients (21%) had a bifurcated graft. Thus, 52 admitted patients did not have an intervention (Table II; Fig 3). A majority of these patients were dead or moribund at the time of diagnosis (five were dead on arrival, six had a cardiac arrest in the emergency department, and three were agonal at the time of diagnosis) or were admitted to other departments and died without rAAA being suspected and diagnosed first on autopsy. Crude and adjusted mortality trends. The crude and adjusted mortality rates showed some variation over time,
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4 Reite et al
Fig 3. Intervention rate in admitted patients.
Fig 2. Adjusted incidence rate by gender.
Table II. Site and mode of death in patients with fatal ruptured abdominal aortic aneurysm (rAAA) All deaths Prehospital deaths In-hospital deaths Did not want operation Considered unfit for surgery Metastatic disease Agonal at time of diagnosis Diagnosed on autopsy Perioperative deaths
No. (%) (N ¼ 146) 20 (14) 126 (86) 10 15 1 14 12 77
but not significantly (Figs 4 and 5). The crude mortality rate for the study period was 6.4 per 100,000 persons per year, and the corresponding adjusted mortality rate was 7.5 (95% CI, 6.3-8.8). When comparing the early and late periods of the study, we found no statistically significant difference (P ¼ .884) in mortality rate. The 90-day standardized mortality ratio for the study period was 37.2 (95% CI, 31.6-43.7) and, when split for gender, 39.3 (95% CI, 32.6-47.5) in men and 32.0 (95% CI, 23.2-44.2) in women (Fig 6). The 90-day total mortality was 68% (146 of 216 persons), somewhat higher than what was observed within 30 days (138 deaths; 64%). A total of 144 patients (67%) had an operation. The postoperative 90-day mortality was 51% (74 of 144), 57% (12 of 21) in women and 50% in men (62 of 123) (P ¼ .568). DISCUSSION We found the adjusted incidence rate for the study period to be 11.0 per 100,000 per year (95% CI, 9.612.5). Although considerable disparities in incidence rate
Fig 4. Crude mortality rate.
have been reported within Norway,6 the findings correspond well with a fairly recent Scandinavian report.15 SUH has a care pathway for aneurysms. If a patient is admitted with suspected rAAA or rAAA is expected after the patient has been assessed in the emergency department, the vascular surgeon on call and the anesthesiologist on site will be summoned. The radiologist is on site and will perform ultrasound in the emergency department in unstable patients; stable patients will be taken for CT examination. If recent renal function test results are not available at the time of CT, the first run will be without contrast material; a subsequent run with contrast material will be performed at the discretion of the attending vascular surgeon. A dedicated vascular operation room is available aroundthe-clock. As of today, SUH has no hybrid suites. However, the service provided is devoid of referral bias and diagnostic delay, as the hospital covers all patients in the region for a centralized, one-stop, protocol-committed care for all vascular emergencies.16,17 Altogether, 27% (52 of 196) of the patients who were admitted to the hospital did not have an intervention.
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Fig 5. Adjusted mortality rate.
Notably, most previous studies report a substantially higher nonintervention rate.15,16 Lower nonintervention rates are rarely reported, with only two previous studies reporting numbers below 20% (19% and 9%, respectively),18,19 and neither of these studies published the clinical or forensic autopsy rates in the relevant catchment areas. In our study, a substantial portion of the “nonintervention” patients were diagnosed post mortem (n ¼ 12) or were moribund or agonal (n ¼ 14) at the time of diagnosis. Thus, excluding these 26 patients, the nonintervention rate may be considered at 15% (26 of 170 eligible for surgery), and among these 26 patients alive and potentially eligible for intervention, the decision to not intervene was based on the patient’s own expressed wish and decision in 38% (10 of 26). High autopsy rates are necessary to obtain valid rAAA rates. A few dated papers examining rAAA in the 1970s and 1980s reported very high autopsy rates of 61% to 85%20,21 and found that up to 40% of patients with rAAA died outside of the hospital. During the observation period, the rate of autopsy of in-hospital deaths in SUH varied from 28% to 19%, whereas the rate of forensic autopsies was stable throughout the period (41 to 47 of 100,000 per year). Forensic autopsies may not be performed in elderly patients in a care institution or for patients with known terminal disease. This may introduce a bias regarding the autopsy finding; however, we believe this to be of little clinical relevance as such cases are unlikely to be suitable for intervention. In our study, 9% died before hospitalization. Autopsy rates of 60% to 80% cannot be matched today with a global decline in autopsy rates; thus, it is reasonable to assume that newer studies systematically underestimate the incidence of rAAA. On the other hand, one may theorize that the threshold for seeking medical help is lower and the availability of health care services including cross-sectional body imaging is better and more
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Fig 6. The 90-day standardized mortality ratio stratified by gender.
prevalent in the population. The emergency medical services serving SUH have reported high survival rates and short response time after out-of-hospital arrest in previous studies.22 Efficient emergency medical services may be a contributing factor in the low numbers of prehospital deaths. The overall mortality (68%) in the current study is in contrast to the findings of a recent meta-analysis of population-based mortality of rAAA analyzing 24 papers published since 1977, which reported a pooled mortality of 81% (95% CI, 78-83).11 Meta-analyses found that the mortality of rAAA has improved during the last few decades.11,23 We did not find any change in mortality between early and late time periods in the current study. Most papers on rAAA and survival report only inhospital mortality or include a selected population.24,25 Overall mortality in rAAA is determined by the number of patients dying in the prehospital phase, the number of admitted patients not having an intervention, and the perioperative mortality in those undergoing surgery. Previous studies report widely divergent results on perioperative mortality. Studies with the better results (ie, mortality 40%) when nonintervention rates are reported.15,16,19 In our series, the operative mortality was 51%. One may speculate that there is an inverse relationship between low nonintervention rates and high perioperative mortality. This needs to be considered in evaluating studies from different regions and of differing outcomes. Whereas the strict population-based design with excellent coverage for prehospital and in-hospital deaths from rAAA is among the strengths of this study, some limitations
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deserve to be mentioned. The time period covered by our study may be too short and may possibly involve too few patients to demonstrate any significant trends in the incidence of rAAA. No significant differences can be found in the time plots; the CIs are overlapping. Recent papers report that the incidence of AAA is waning,30 but because of lag, this trend is only slowly starting to affect the incidence of rAAA.15,31,32 A considerable majority (79%) of the patients were men; but contrary to what others have reported, the few women did not have significantly higher perioperative mortality than the men. Other authors report a gender difference in mortality and argue that although women presenting with rAAA are significantly older than men, the difference in mortality seems to persist even when adjusted for age.33 Some have suggested that one contributing factor may be that cardiovascular disease is underdiagnosed in many women.34 This and other similar studies show the limitations of open repair of rAAA (ie, high mortality). The study is not designed to address the questions of whether a screening program or EVAR may change the risk of rupture or mortality in rAAA, but we find it pertinent to address these issues briefly. Several studies have shown that screening programs reduce the risk of aneurysmrelated deaths.35 Several larger studies demonstrate better survival with increased use of EVAR,36,37 although the smaller randomized clinical trials have failed to find a survival benefit.37 During the study period, we established EVAR for elective repair; but as of today, only one rAAA has been treated by EVAR. Taking up EVAR in rAAA is dependent on local expertise and facilities and logistics. In our case, the main obstacle has been and still is funding of a hybrid laboratory. We find the angiography suite unsuitable for EVAR in rAAA as some patients will need an open operation or open adjuncts to EVAR. CONCLUSIONS The overall mortality of rAAA in this study was 68%. This is lower than in most other studies and metaanalyses. The difference is not due to lower perioperative mortality (51%), but few patients died in the prehospital (9%) phase, and the intervention rate was high (73%) in patients admitted alive. There was no significant difference in incidence or mortality between early and late in the 13-year study period. A considerable majority of patients were men (79%), but the few women did not have a significantly higher postoperative mortality than men. AUTHOR CONTRIBUTIONS Conception and design: AR, KS, MV Analysis and interpretation: AR, KS, JK, MV Data collection: AR, CE, MV Writing the article: AR, KS, CE, JK, MV Critical revision of the article: AR, KS, CE, JK, MV Final approval of the article: AR, KS, CE, JK, MV
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Submitted Oct 6, 2014; accepted Dec 18, 2014.
