How to cite this article: Enríquez-Vega ME, Solorio-Rosete HF, Cossío-Zazueta A, Bizueto-Rosas H, Cruz-Castillo JE, Iturburu-Enríquez A. Early detection of abdominal aortic aneurysm in risk population. Rev Med Inst Mex Seguro Soc. 2015;53 Supl 1:S100-3.
Received: October 22nd 2014
Accepted: March 6th 2015
María Elizabeth Enríquez-Vega,a Hugo Francisco Solorio-Rosete,b Alfonso Cossío-Zazueta,c Héctor Bizueto-Rosas,d Juan Ernesto Cruz-Castillo,d Alessandra Iturburu-Enríqueze
aServicio de Angiología y Cirugía Vascular. Facultad de Medicina, División de Estudios de Posgrado Universidad Nacional Autónoma de México
bAngiólogo y Cirujano Vascular, Querétaro, Querétaro, México
cServicio de Cirugía
dServcio de Angiología y Cirugía Vascular
c,dCentro Médico Nacional La Raza, Instituto Mexicano del Seguro Social, Distrito Federal
Communication with: María Elizabeth Enríquez-Vega
Teléfono celular: 5554313286, fax: 57547724
Background: An aneurysm is the increase in diameter of an artery > 50 %; the abdominal aortic aneurysm (AAA) is the most frequent. Abdominal ultrasound is an accessible study, highly recommended for diagnosis. Screening at risk populations reduces morbidity and mortality of this disease.
Methods: To determine the frequency of AAA by duplex Doppler in patients older than 65 years old with risk factors. A cross sectional study was performed, from June to October 2012, 144 patients were included, both genders, > 65 years. The diameter of the infrarenal abdominal aorta was measured by duplex Doppler. AAA was defined as an aorta with diameter > 3 cm.
Results: Mean age was 72.7 ± 6.7, 95.1 % were male, 13 % continued smoking. 127 of 144 were normal. 10 of 144 had AAA with diameters of 3.2 to 7.11 cm, all of them male. Logistic regression showed that active smoking is a significant predictive factor for AAA.
Conclusion: There is a significant frequency of AAA in male patients > 65 years old.
Keywords: Abdominal aortic aneurysm, Ultrasound Doppler duplex, Detection.
An aneurysm is the increase in diameter of an artery > 50 % relative to an initial diameter. Infrarenal abdominal aortic aneurysms (AAA) are the most common, accounting for about 75% of all aneurysms.1 An operational definition of practical interest indicates that a transverse diameter greater than 3 cm should be listed as AAA.2,3
70 to 75% of AAA are asymptomatic, a large proportion of them are discovered as imaging findings in the study of other pathologies. In our country there are no early detection programs. When the diagnosis is made the aneurysm is already very large and this increases morbidity and mortality.4,5 The most feared complication of AAA is rupture, whose calculated postoperative mortality is 47%; however, 66% of patients presenting with a ruptured aneurysm die before reaching the hospital or before entering surgery, so that overall mortality is in the range of 77 to 90%,6,7 while 30-day mortality for elective surgery is 5 to 8%.5,7,8
The diagnosis by physical examination has a sensitivity of 39% and this improves as the size of the aneurysm increases, to 76% for AAA greater than or equal to 5 cm in diameter. Abdominal ultrasound is an accessible and useful test for the detection of AAA with a sensitivity of 87.4% and a specificity of 99.9%.6 Computerized axial tomography (CAT) is the gold standard for diagnosis as well as for the surgical plan with a sensitivity and specificity that exceed 95%.7,9
There are numerous references in the literature about screening for AAA in patients at risk, the 4 most important randomized controlled studies being: Multicentre Aneurysm Study (MASS),10 Chichester,11 Viborg,12 and Western Australia.13,14
There is enough scientific evidence to justify conducting AAA screening in male patients over 65 years.9,15-17 The American Society for Vascular Surgery recommends secondary detection for AAA in male patients over 65 years with or without a history of smoking and female patients 65 and older with a history of smoking, and performing Doppler ultrasound monitoring at three years for aortas that have a diameter greater than 2.6 cm.18 Unfortunately in Latin America there are few studies of AAA screening, and in Mexico there are none.
A longitudinal, descriptive, prospective study was performed in the period between June and October 2012 with the main objective to estimate the frequency of AAA using duplex Doppler ultrasound in patients of both sexes over 65 years.
The following were taken as criteria: men 65 years or older with or without a history of smoking, and women with a history of smoking 65 years or older. A questionnaire was applied to obtain the following information: sex, age, smoking history, hypertension, diabetes mellitus (DM), and dyslipidemia. Duplex Doppler scanning was performed at the patient’s bedside, the infrarenal abdominal aorta was identified, and by a cross-section the maximum anterior-posterior diameter was identified. Diameter greater than or equal to 30 mm was used as a diagnostic criterion for AAA.
All information was captured and analyzed in SPSS version 11. Measures of central tendency (mode, mean, median, standard deviation) were analyzed. Logistic regression analysis was used for diagnostic predictors for AAA.
144 patients admitted to the Hospital de Especialidades were included; demographic data (Table I) was collected. The mean age was 72.7 ± 6.7, and 95.1% of patients were male. Of the total patients, 13% continued to smoke and 31.3% had a history of consuming more than 10 cigarettes a day. 2.8% had no control of systemic blood pressure. A total of 146 ultrasounds were performed, 2 patients were excluded from the study because it was not technically possible to visualize the abdominal aorta. A total of 10 AAA (6.9%) were detected, all of them in men; the 93.1% (134 patients) remaining had an abdominal aorta diameter of 1.6 to 2.9 cm, which is considered normal (Table II).
|Table I Risk factors for abdominal aortic aneurysm|
|Table II Abdominal aorta diameter in study population|
|Diameter of aorta
The logistic regression analysis showed that active smoking is a significant predictive factor for diagnosis of abdominal aortic aneurysm, and that it increases the risk by 8.5 times compared to patients who do not smoke.
Abdominal aortic aneurysms have an increasing incidence in the population of adults over age 65; therefore, it is of utmost importance to implement a detection method for early diagnosis and treatment, in addition to the prevention of complications associated with this condition, which can reach up to 70% in the case of emergency surgery, compared with less than 5% in patients undergoing elective surgery.
The literature has reported four randomized studies for early detection of AAA, the Multicentre Aneurysm Screening Study (MASS),10 Chichester,11 Vibord,12 and Western Australia;13,14 concluding that screening men over 65 years gives a significant decrease in mortality in elective AAA repair and a decrease in emergency surgery.17
The MASS study included 67,800 men with an age range of 65 to 74 years, who were divided into two groups. Group 1 (n = 33 839) was given Doppler abdominal ultrasound, detecting 1333 AAA, and group 2 (or control) was not given any test; both groups were given follow-up. In the control group there were more emergency surgeries, AAA-associated mortality was 113 in the control group and 65 in the problem group (OR = 0.58, 95% CI = 0.42 - 0.78). Total mortality from all causes did not differ between the groups. The study concluded that screening programs result in decreased mortality associated with AAA. The authors recommend that the screening be carried out only in men over 65 years due to a low incidence of AAA in women.9,10
In Viborg, Denmark, Lindholt and Juul12 studied a population of 12,639 men between ages 64 and 73. The results were that 512 AAA were detected. The control group (6306) underwent 31 interventions (20 emergency and 11 scheduled), died 27 of AAA, and 1019 from all causes; with screening, AAA-specific mortality is reduced by 67% and emergency surgery by 75%; the study concludes that AAA-related mortality is reduced by a screening program and for Danish men aged 64-73 years, this appears to be cost-effective. Reassessment is unjustified when the diameter of the abdominal aorta is less than 2.5 cm, but it is necessary at 5 years if the diameter is between 2.5 and 2.9 cm.12
In Australia, Jamrozik and Brown conducted a study involving 41,000 men between 65 and 79 years, the results were: the prevalence of AAA is 7.2%, strongly dependent on age: 4.8% between 65-69 years, 7.6% between 70-74 years, 9.7% between 75-79 years, and 10.8% between 80-83 years; aneurysm size increased with age. In relation to the diameter, out of 875 AAA discovered, 699 (80%) measured between 3 and 4.4 cm; 115 (13%) between 4.6 and 5.4 cm, and 61 (7%) equal to 5 cm or more. There was increased mortality at 30 days after emergency surgery (4/7, 24%) than after elective surgery (7/161, 4.3%). Follow-up was performed every 6-12 months when the size of the aorta was between 3 and 4.9 cm, and it was referred to surgery if it was greater than or equal to 5 cm. The study concluded that screening men between 65 and 74 years reduces mortality associated with AAA.13,14
A review by Crochane in 2009 revealed a reduction in AAA-related mortality in men (OR = 0.60; 95% CI: 0.47 to 0.78); this analysis included surgical mortality from emergency or elective AAA repair.17 International guides recommend performing screening in all men over 65 and women under 65 with a history of smoking; however, for screening to be useful, it is necessary to first establish that in the population there is an incidence greater than 4% in preliminary studies.
The result of this study shows that the frequency of AAA in patients with risk factors in our country is 6.9% and that the most frequently encountered diameter ranges between 3 and 4 cm; aneurysms of this size are totally asymptomatic and only can be detected by imaging studies. The risk factor most associated with AAA was smoking, not so with DM2 which seems to act as a protective factor; 59% of patients had a history of hypertension and 47% of dyslipidemia. The results of this study are added to the only two studies published in Latin America (Table III), which report low percentages compared to those found in our study.19,20
|Table III Studies of screening with duplex Doppler ultrasound for detection of abdominal aorta aneurysm in Latin America|
|Study of screening||AAA||Citation|
|Colombia||5.26% (n= 113)||Dr. Proveda19|
|Argentina||4.49% (n= 280)||Dr. Grosso20|
The reported frequency of asymptomatic AAA in patients with risk factors in our study was 6.9%, and routine detection by duplex Doppler study is suggested to identify the disease, in order to reduce morbidity and mortality.21
Conflict of interest statement: The authors have completed and submitted the form translated into Spanish for the declaration of potential conflicts of interest of the International Committee of Medical Journal Editors, and none were reported in relation to this article.