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Issue 9: Endovascular Repair for Abdominal Aortic Aneurysm

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Context

An abdominal aortic aneurysm (AAA) is a permanent and localized increase in size  of the main blood vessel in the abdomen.  A ruptured aneurysm can cause severe internal bleeding leading to shock or even death.

Early detection and treatment of an AAA can avoid the life-threatening risk of rupture.1 The condition is frequently silent and rupture can be the first symptom.2 A ruptured AAA is associated with a mortality rate of about 80%.3 AAA is a significant cause of death in Canada; and  it is especially common in men over the age of 65.1 Each year, physicians diagnose approximately 20,000 people in Canada with an AAA; of those, nearly 2,000 may have an AAA that is threatening enough to cause death from a rupture, if not treated.4

The two most common treatment options for AAA include an open surgery option or an endovascular aortic repair (EVAR). Approximately 25% of patients with an AAA requiring surgery are not considered good candidates for open surgical repair.3 In the US, EVAR has replaced open repairs as the most commonplace procedure for treating AAAs.5 In Canada, open repair is still the most frequently practiced approach.

Individuals with non-urgent cases that require elective repair are associated with better outcomes than those treated for aortic rupture. Elective surgical repair is available across Canada and is usually recommended for all aneurysms greater than 5 cm to 6 cm in diameter, unless patients are judged as medically unfit for surgery.2 There are no treatments for smaller, earlier-stage AAAs beyond basic monitoring of progression and blood pressure management.6 Surgical intervention for AAAs that are 5 cm in diameter or larger is typically advised, as they grow at an average rate of 5 mm per year.7

The recently published results of two long-term randomized studies comparing EVAR with open repair (EVAR 1 and DREAM trials),8,9 found that short-term mortality outcomes (30 days post-surgery) favoured EVAR. The initial advantage of EVAR, however, dissipated over the long term, with no demonstrated statistical difference in overall survival rates after five to six years between the two groups. Additionally, the EVAR procedure was associated with higher rates of graft-related complications and reinterventions. EVAR was also the more costly intervention.

The use of EVAR in lower-risk patient populations has also been reviewed in Ontario.6  Recommendations from this review suggest that for patients at low operative risk for open surgical repair, EVAR cannot be supported from a health system perspective because it is not cost-effective and provides no overall advantage in terms of survival or complication rates.6

Given current recommendations and new evidence from the EVAR 1 and DREAM trials, there is some interest in current practice patterns and what represents optimal clinical practice. There is evidence that patients perceive the EVAR approach as attractive compared with open repair as it is less-invasive. However, EVAR may not be a sustainable approach for every patient requiring AAA repair.

Objective

The purpose of this report is to provide a current status of the utilization of open surgical repair and EVAR for the management of AAAs, grouped by calendar year and Canadian jurisdiction. Results of this report are based on data from the Canadian Institute for Health Information’s (CIHI) Discharge Abstract Database. Information includes calendar year data from 2006 to 2008 and is based on the International Classification of Diseases procedure code (ICD-10-CA).

Results

Overall, 2,948 AAA procedures (open repair and EVAR) were performed in nine provinces across Canada in 2008 (data for Quebec are not included). Of these procedures, 62% were for open surgical repair and 38% were for EVAR. Ontario accounted for almost 50% of all national AAA procedures; 60% of Ontario’s AAA interventions were for open surgery and 40% were for EVAR. British Columbia carried out the second highest amount of AAA procedures; accounting for 16% of the national total. While British Columbia carried out fewer total procedures than Ontario, it performed relatively more EVAR procedures (47% versus 40%) relative to the number of total procedures performed compared with Ontario (Table 1). Figure 1 provides a pan-Canadian comparison of EVAR and open repair surgical procedures for 2008.

AAA = abdominal aortic aneurysm; Alta. = Alberta; BC = British Columbia; EVAR = endovascular aortic repair; Man. = Manitoba; NB = New Brunswick; Nfld. = Newfoundland and Labrador; NS = Nova Scotia; Ont. = Ontario; NWT = Northwest Territories; PEI = Prince Edward Island; Sask. = Saskatchewan.

Figure 1: Number of Total Cases, Open Surgical and EVARs Listed per Province and Territory in 2008

(This figure was based on a similar figure previously published by Forbes et al. in: Forbes T, et al. J Vascular Surg 2005;42(3):410-414.)

Alta. = Alberta; BC = British Columbia; EVAR = endovascular aortic repair; Man. = Manitoba; NB = New Brunswick; Nfld. = Newfoundland and Labrador; NS = Nova Scotia; Ont. = Ontario; NWT = Northwest Territories; PEI = Prince Edward Island; Sask. = Saskatchewan.

Figure 2 shows that in 2008, Ontario performed 54% of the total number of EVAR procedures across Canada. British Columbia and Alberta performed the next largest amount (20% and 13% of total procedures performed respectively). Newfoundland and Labrador, Prince Edward Island, Nova Scotia, New Brunswick, Manitoba, and Saskatchewan collectively performed approximately 14% of the total number of EVAR procedures for that year.

Figure 2: Percentage of Total EVAR Procedures in Canada by Province in 2008

Alta. = Alberta; BC = British Columbia; EVAR = endovascular aortic repair; Man. = Manitoba; NB = New Brunswick; Nfld. = Newfoundland and Labrador; NS = Nova Scotia; Ont. = Ontario; NWT = Northwest Territories; PEI = Prince Edward Island; Sask. = Saskatchewan.

In 2006, 2,053 open AAA surgeries were performed, compared with 1,828 respectively in 2007 and in 2008. During this three-year period, this represents a 9% decline in the number of open surgeries. During this same period, the number of EVAR procedures grew from 732 in 2006 to 966 in 2007 and there were 1,120 in 2008, representing a 35% increase in EVARs during these three years. Figure 3 provides a graphical display of this information.

Figure 3: Total EVARs and Open Surgeries by Year in Canada, 2006 to 2008

Figure 4 depicts the trends in the number of cases of EVAR procedures between 2006 and 2008 by province. Overall, there were 4,911 open procedures conducted during the three years, compared with 2,818 EVAR procedures. During this period, Ontario performed the most open surgical procedures (2,737 cases) and EVAR procedures (1,374 cases). Prince Edward Island produced the least open surgical procedures (25 cases) and EVAR procedures (seven cases). In addition, Prince Edward Island was not conducting any EVARs in 2006, but by 2008, four EVAR procedures were carried out in the province. These trends can be seen in Figure 4.

Figure 4: Trends in the Recent Number of Cases of EVARs by Province, 2006 to 2008

Alta. = Alberta; BC = British Columbia; EVAR = endovascular aortic repair; Man. = Manitoba; NB = New Brunswick; Nfld. = Newfoundland and Labrador; NS = Nova Scotia; Ont. = Ontario; NWT = Northwest Territories; PEI = Prince Edward Island; Sask. = Saskatchewan.

Limitations

This analysis is a preliminary analysis and does not attempt to show the number of cases by type of patient, provincial demographics, or number of surgeons and programs available. For example, the number of procedures performed on an urgent basis or those performed in low-risk patients is not analyzed, A more thorough examination might be of interest to those involved in setting clinical or public policy benchmarking.

Conclusion

The practice of EVAR is increasing in Canada, particularly in Ontario, British Columbia, and Alberta. It remains to be seen if current recommendations and emerging evidence will have an impact on future practice patterns.

References

  1. Abdominal aortic aneurysm backgrounder. Ottawa: Canadian Society for Vascular Surgery; 2008.
  2. Clinical policy bulletin: endovascular repair of aortic aneurysms.Aetna; 2009. Available from: http://www.aetna.com/cpb/medical/data/600_699/0651.html
  3. Chambers D, Epstein D, Walker S, Fayter D, Paton F, Wright K, et al. Endovascular stents for abdominal aortric aneurysms: a systematic review and economic model. Health Technol Assess. 2009;13(4). Available from: http://www.hta.ac.uk/1678
  4. Abdominal aortic aneurysm screening & treatment options. Toronto: Toronto Endovascular Centre; 2009. Available from: http://www.torontoendovascularcentre.com/pat/background.html
  5. Karthikesalingam A, Thompson M, Holt P. The link between volume and outcome in endovascualr aneurysm repair. Future Med. 2010;2(1):3-5. Available from: http://www.futuremedicine.com/doi/pdf/10.2217/ica.09.142
  6. Endovascular repair of abdominal aortic aneurysms for low surgical risk patients. Toronto: Ontario Health Technology Advisory Committee; 2010. Available from: http://www.health.gov.on.ca/english/providers/program/ohtac/tech/recommend/rec_evar_20100113.pdf
  7. Gagnon J. Abdominal aortic aneurysms diagnosis and treatment. Vancouver: Vancouver General Hospital, University of Britsh Columbia; 2009.
  8. De Bruin J, Baas A, Buth J, Prinssen M, Verhoeven E, Cuypers P, et al. Long-term outcome of open or endovascular repair of abdominal aortic aneurysm. N Engl J Med. 2010;362(20):1881-9.
  9. UK EVAR Trial Investigators. Endovascular versus open repair of abdominal aortic aneurysm. N Engl J Med. 2010;362(20):1863-71.

Cite as: Morrison, A. Abdominal Aortic Aneurysm [Environmental Scan issue 9]. Ottawa: Canadian Agency for Drugs and Technologies in Health; 2010.

CADTH takes sole responsibility for the final form and content of this environmental scan. The statements and conclusions in this environmental scan are those of CADTH.

Production of this report is made possible by financial contributions from Health Canada, and the governments of Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Northwest Territories, Nova Scotia, Nunavut, Prince Edward Island, Saskatchewan, and Yukon. The Canadian Agency for Drugs and Technologies in Health takes sole responsibility for the final form and content of this report. The views expressed herein do not necessarily represent the views of Health Canada or any provincial or territorial government.

Disclaimer: The Environmental Scanning Service is an information service for those involved in planning and providing health care in Canada. Environmental Scanning Service responses are based on a limited literature search and are not comprehensive, systematic reviews. The intent is to provide information on a topic that CADTH could identify using all reasonable efforts within the time allowed. Environmental Scanning Service responses should be considered along with other types of information and health care considerations. The information included in this response is not intended to replace professional medical advice nor should it be construed as a recommendation for or against the use of a particular health technology. Readers are also cautioned that a lack of good quality evidence does not necessarily mean a lack of effectiveness, particularly in the case of new and emerging health technologies for which little information can be found but that may in future prove to be effective. While CADTH has taken care in the preparation of the report to ensure that its contents are accurate, complete, and up to date, CADTH does not make any guarantee to that effect. CADTH is not liable for any loss or damages resulting from use of the information in the report.

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