Cost-effectiveness of screening women for abdominal aortic aneurysm

BACKGROUND: Women are usually not considered for abdominal aortic aneurysm (AAA) screening because of their lower prevalence of disease. This position may, however, be questioned given the higher risk of rupture and the longer life expectancy among women. The purpose of this study was to assess the cost-effectiveness of screening 65-year-old women for AAA. METHODS: A systematic review of the literature was conducted to obtain data of importance to evaluate the effectiveness of screening women for AAA. Data were entered into a Markov simulation cohort model. RESULTS: The review suggested some main assumptions for women with AAA. Prevalence is 1.1%. In 6.8%, the AAA is of a size that merits surgery, and the patients are fit for a procedure. For patients with an AAA, the yearly risk for elective surgery and the rupture incidence was 3.1% and 2.4%, respectively, in the invited group and 1.1% and 5.7% in the noninvited group. The operative mortality for elective surgery was 3.5%, and the total mortality for ruptured AAA was 86.3%. The long-term mortality for AAA patients was 3.6 times higher than for an age-matched healthy population. Screening reduced the AAA rupture incidence by 33% and the AAA-related death rate by 35%. The cost per life year gained was estimated at $5911. CONCLUSION: The incremental cost-effectiveness ratio was similar to that found for screening men, which reflects the fact that the lower AAA prevalence in women is balanced by a higher rupture rate. Screening women for AAA may be cost-effective, and future evaluations on screening for AAA should include women.     

Project PROMIS: Peoria Regional Outpatient Medical Imaging Study

BACKGROUND: Abdominal aortic aneurysm (AAA) accounts for > 15,000 reported deaths annually. Early screening in high-risk populations is important to decrease morbidity and mortality from rupture. METHODS: A prospective, population-based study of free ultrasound-based AAA screening was conducted from July 2004 to December 2006. Before examination, subjects completed surveys asking their medical history, including known AAA risk factors. Incidence rates and comparison analyses were performed. RESULTS: The final analysis included 979 patients, of whom AAA was discovered in 27 (2.8%). AAA was found in only male patients > 60 years old (4% of the male population). AAA size ranged from 3 to 10 cm. Of patients diagnosed with AAA, 85% were current or past smokers, and 70% had hypercholesterolemia. There was a 6% incidence of AAA in male smokers > or = 60 years old who had hypercholesterolemia. CONCLUSIONS: Four factors were predominant in our population of patients with AAA: patient age, male sex, smoking history, and hypercholesterolemia.     

The value of screening in siblings of patients with abdominal aortic aneurysm.

OBJECTIVES: This study aimed to determine the incidence of abdominal aortic aneurysm (AAA) in a large group of siblings of Australian AAA patients to determine if screening in this group is justified. METHODS: 1254 siblings of 400 index AAA patients were identified and offered aortic ultrasound screening. An age and sex matched control group was recruited from patients having abdominal CT scans for non-vascular indications. AAA was defined by an infrarenal aortic diameter of > or =3 cm or a ratio of the infrarenal to suprarenal aortic diameter of > or =2.0. A ratio of 1.0-1.5 was considered normal, and a ratio of >1.5 to <2.0 was considered ectatic. Aortic enlargement was defined as ectasia or aneurysm. RESULTS: 276 (22%) siblings could be contacted and agreed to screening or had previously been diagnosed with AAA. All 118 controls had normal diameter aortas. 55/276 siblings had previously been diagnosed with AAA. The remaining 221 siblings underwent ultrasound screening. Overall, 30% (84/276) had enlarged aortas (5% ectasia, 25% aneurysmal); 43% of male siblings (64/150) and 16% of females siblings (20/126). The incidence was 45% in brothers of female index patients, 42% in brothers of male patients, 23% in sisters of female patients, and 14% in sisters of male index patients. CONCLUSIONS: The overall incidence of aortic enlargement of 30% found in this study warrants a targeted screening approach with ultrasound for all siblings of patients with AAA. A similar targeted approach for screening of the children of AAA patients would also seem advisable.     

Abdominal aortic aneurysm screening in Sweden

A large body of evidence from four international randomised controlled trials (RCT) on abdominal aortic aneurysm (AAA) screening indicate that ultrasound-based screening in elderly men with a high prevalence (4?%–7?%) reduces AAA-related mortality by 40?% through early AAA detection and increased preventive elective repair and subsequently halves rupture incidence. Coinciding with the planned launch of national AAA screening programs, a dramatic change in AAA epidemiology became evident: a lower AAA prevalence in the targeted population of men and falling mortality rates, most likely related to a drop in rates of smoking, and a paradoxical increase in elective AAA repairs. These changes have called AAA screening in today’s context into question. Sweden was the first country to provide national coverage with an AAA screening program targeting 65-year-old men. The scientifically evaluated screening initiative, started in 2006, reported the lower than expected prevalence (1.7?%) in 65-year-old men early on. Cost-effectiveness seems to be maintained despite the altered epidemiology, as shown in a health-economic study. The current prevalence of AAA among Swedish women is very low, and general population-based screening of women is likely to be futile, although targeted screening among female smokers should be evaluated. Sub-aneurysmal aortas detected at screening are likely to progress to a true AAA within 5 years, indicating a need for continued surveillance in this group. Differences in screening compliance seem to be linked to socio-economic factors. The aim of this topical review is to highlight AAA screening within a Swedish context and point to areas where information is lacking and further research is needed.     

Effectiveness and cost of screening for abdominal aortic aneurysm: results of a population screening program

OBJECTIVES: We undertook this study to calculate the cost per life-year gained in the first round of a screening program for abdominal aortic aneurysm (AAA) and to estimate the costs in a subsequent round. METHODS: This was an intervention study, with follow-up for ruptured aneurysms. Men older than 50 years were screened for asymptomatic AAA. Outcome measures included cost per life-year saved and number of men needed to be screened to save one life. RESULTS: The incidence of ruptured AAA was 2.6 per 10,000 person- years in the screening group and 7.1 per 10,000 person-years in the control group. Screening is estimated to have prevented 10.8 ruptured AAA and 8 deaths per year, gaining 51 life-years per year for the study population, and to have reduced the incidence of ruptured AAA by 64% (95% CI, 42%-77%). Each life-year gained during the first screening round cost $1107. To save one life, 1000 men need to be screened and 5 elective operations performed. We predict that a second round of screening can be cost neutral. CONCLUSIONS: The cost-effectiveness of screening for AAA compares favorably with screening programs for other disorders in adults.     

Screening for abdominal aortic aneurysms in cardiovascular patients

BACKGROUND: The objective of the study was to determine the incidence of Abdominal Aortic Aneurysms (AAA) in a population of symptomatic cardiac patients. A retrospective cohort study of investigations was done at the cardiology clinic, Beaumont Hospital, Dublin. MATERIALS AND METHODS: There were 415 men and women recruited by referral to the cardiology clinic. All participants underwent routine ultrasound screening for AAA, and full assessment of all cardiac risk factors. Data were analyzed and correlated with age, sex, and diagnosis. RESULTS: Ultrasonographic diagnosis of aneurysm was based on an anteroposterior diameter of 3 cm or more. Of the 415 patients screened, 47 aneurysms were detected. Total incidence of AAA was 9.9% (male 14.1%, female 3.95%). All aneurysms were detected in patients over 60 years, detection rate 11.7% (male 16.3%, female 3.9%). The incidence of AAA was significantly higher in those who were subsequently proven to have cardiovascular disease, 13.8% (male 18%, female 5.15%). CONCLUSION: Screening the general population for those at risk of AAA is an ongoing debate. This study supports the concept of screening a higher risk population of patients over 60 years with cardiovascular disease.     

The true incidence of ruptured abdominal aortic aneurysms

The number of ruptured abdominal aortic aneurysms (RAAA) was documented over an 8-year-period in a known population age group. Patient figures were collected from the operative and post-mortem registers in the Worthing Health District. The overall mean incidence of RAAA was 13.9/100,000 patient years, although the incidence was noted to increase from 9.2 to 17.5/100,000 patient years during this period. The incidence in the male population rose from 4.7/100,000 for those in the fifth decade to 184.8/100,000 for those above 80. For patients undergoing operation, the peri-operative survival was 38%, however the overall survival was 11% as 64% of patients died at home. These figures demonstrate an increasing incidence of ruptured AAA. They also add support to the need for screening of asymptomatic abdominal aortic aneurysms and elective repair if the incidence and hence mortality is to be reduced.     

The cost-effectiveness of a "quick-screen" program for abdominal aortic aneurysms

BACKGROUND: The incidence of abdominal aortic aneurysm (AAA) is increasing, and the prognosis of ruptured AAA remains dismal. Early diagnosis and intervention are crucial. We designed this study to determine whether selected population screening with a brief "quick-screen" ultrasound could be cost-effective. METHODS: A series of 25 patients with risk factors for AAA were evaluated in a blinded fashion by a quick-screen ultrasound and a full conventional study. Times and accuracy for the 2 approaches were compared. An analysis of the cost-effectiveness of screening for AAA was then performed using a Markov model. We determined the long-term survival in quality-adjusted life years and lifetime costs for a hypothetical cohort of 70-year-old males undergoing either AAA screening or not. Our measure of outcome was the cost-effectiveness ratio (CER). RESULTS: The average time for a quick screen was one-sixth that of a conventional study (4 vs 24 minutes). The accuracy of the quick screen was 100%. In our base-case analysis, screening for AAA was cost-effective with a CER of $11,215. Society usually is willing to pay for interventions with CER of less than $60,000 (eg, CER for coronary artery bypass grafting, $9500; breast cancer screening, $16,000). In sensitivity analysis, reducing the cost of screening from $259 (approximate Medicare reimbursement) to $40 (the quick screen) improved the CER to $6850. Moreover, screening populations with increased prevalence of AAA (eg, male with family history [18%]) further improved the CER. CONCLUSIONS: Our analysis demonstrates that ultrasound screening for AAA should be offered to all males above the age of 60. Widespread screening for AAA should be adopted and reimbursed by Medicare and other insurers.     

Epidemiology of abdominal aortic aneurysm in an Asian population

Background: Abdominal aortic aneurysms (AAA) are common in the Caucasian population. Apart from reported differences in the occurrence of AAA in the black and white populations, there are few studies on the incidence of AAA in the Asian population. Methods: A prospective database of all patients with AAA seen between 1996 and 1999, in the South‐East Asian state of Sarawak in Borneo Island, was analysed. The demographic data included patient's age, sex, ethnic group, date of diagnosis, comorbidities, presentations and treatment outcomes. These were compared with the state population's demographic statistics. Results: Diagnoses of AAA were made in 123 patients during the study period. The male to female ratio was 3.5 : 1. The age range was 39?88 years with a median age of 70 years. Four patients were younger than 55 years. The incidence rate for the at‐risk male population older than 50 years was 25.6/100 000. The incidence rate reached 78.3/100 000 for males older than 70 years. The incidence rate for females older than 50 years was 7.6/100 000 and for those older than 70 years it was 18.7/100 000. All races were affected. Smoking, hypertension or respiratory disorders were present in more than 40% of the patients. Half of the patients underwent surgical repair. Conclusion: This study shows that AAA in this Asian population is not uncommon and the incidence is comparable to the Western world.     

Prevalence of abdominal aortic aneurysm in Chinese patients with severe coronary artery disease

Background: The Asian population is believed to have lower incidence of abdominal aortic aneurysm (AAA), and hence, the benefit of screening is uncertain. The size of native aorta in Asians, which shall affect the definition of AAA, has also never been reported. Our study investigated the prevalence of AAA and the infra‐renal aortic diameter (AD) in Chinese patients with severe coronary artery disease. Methods: This is a prospective observational study of infra‐renal aortic size for patients who had coronary artery bypass surgery by ultrasound. The patients' demographics, important co‐morbidities and maximum AD were recorded. Results: The study included 624 consecutive Chinese patients (mean age = 63.2 years). The mean maximum infra‐renal AD was 17.5 mm for men and 14.8 mm for women. The presence of AAA was defined as maximum AD greater than 30 mm. The result was also compared with an alternate definition that defines AAA as maximum AD of greater than 1.5 times of the group's mean. Eleven patients had an AD greater than 30 mm, and the prevalence of AAA was only 1.8%. With AAA defined as maximum AD of 1.5 times greater than the group's mean, 19 patients had AAA. The prevalence of AAA in this high‐risk group would become 3% overall. Conclusion: The prevalence of AAA in Chinese patients was low, and the result did not support routine screening. The smaller mean infra‐renal AD in Chinese merits validation by large‐scale study and consideration when deciding threshold for small AAA repair in our locality.     

Fifteen-year follow-up of a randomized clinical trial of ultrasonographic screening for abdominal aortic aneurysms

BACKGROUND: Long-term benefits of screening for abdominal aortic aneurysm (AAA) are uncertain. These are the final results of a randomized controlled screening trial for AAA in men, updating those reported previously. Benefit and compliance over a median 15-year interval were examined. METHODS: One group of men were invited for ultrasonographic AAA screening, and another group, who received standard care, acted as controls. A total of 6040 men aged 65-80 years were randomized to one of the two groups. Outcome was monitored in terms of AAA-related events (surgery or death). RESULTS: In the group invited for screening, AAA-related mortality was reduced by 11 per cent (from 1.8 to 1.6 per cent, hazard ratio 0.89) over the follow-up interval. Screening detected an AAA in 170 patients; 17 of these died from an AAA-related cause, seven of which might have been preventable. The incidence of AAA rupture after an initially normal scan increased after 10 years of follow-up, but was still low overall (0.56 per 1000 person-years). CONCLUSION: Screening with a single ultrasonography scan still conferred a benefit at 15 years, although the results were not significant for this population size. Fewer than half of the AAA-related deaths in those screened positive could be prevented. Registration number: ISRCTN 00079388 (http://www.controlled-trials.com).     

Surgical treatment of abdominal aortic aneurysms associated with aortic valve incompetence: strategies and outcomes

BACKGROUND: The exact incidence of associated aortic valve incompetence (AVI) and abdominal aortic aneurysm (AAA) in the general population is not known. In recent years, we have observed this association with increasing frequency. This observation is probably due to the extensive preoperative screening of the cardiac and vascular status of patients who are candidates for surgical procedures. The choice of the optimal surgical strategy is needed to achieve low operative morbidity and mortality. The present study reviews our experience with a subset of patients suffering the association of AVI and large AAA. Surgical strategy, clinical management and outcome are presented.METHODS: Between January 1982 and May 2000, 76 patients with the association of AAA and AVI have been evaluated in our institution. Forty-four patients have been treated for both AAA and aortic valve (AV) regurgitation. These patients have been divided into three groups on the basis of the surgical strategy adopted. Group 1: combined procedure (16 patients); group 2: AAA repair prior to AV surgery (nine patients); group 3: AV surgery prior to aneurysm repair (19 patients).RESULTS: Hospital mortality was 4.5% (two patients); overall mortality was 6.8% (three patients).CONCLUSIONS: In patients with AAA and AVI, an accurate and complete preoperative evaluation is essential. Surgical strategy should be individualized on the basis of the cardiac preoperative status.     

Making the Case for Cardiovascular Screening in Irish Males: Detection of Abdominal Aortic Aneurysms,and Assessment of Cardiovascular Risk Factors

IntroductionAAA screening programmes have proven to be beneficial and cost effective worldwide for males greater than 65 years of age, with 4.9% males of 65–75 years of age having an un-diagnosed AAA at screening, resulting in a 42% reduction in the risk of rupture in an English population. This study assessed the incidence of AAA and risk factors for atherosclerosis in Irish males of 55–75 years.MethodsFrom April 2006 to December 2007, males between the ages of 55 and 75 years, living within the catchment area of Blanchardstown Hospital were invited for AAA screening using duplex ultrasound and cardiovascular risk factor screening.Results1.9% (17/904) of the study population had previously un-diagnosed aneurysms detected, with sizes ranging from 3.0 cm to 5.8 cm (0.6% in 55–65 years old (yo) and 4.2% in 65–75 yo, p < 0.01). 33% (302/904) of patients had hyperlipidaemia, while 16% of those with a previous diagnosis of hyperlipidaemia, were inadequately controlled on the test date. 31% of patients had a single elevated blood pressure reading, meriting further investigation for possible hypertension. 3% (28/904) of all patients had a raised glucose levels which had not previously been identified and of those who had a previous history of DM, 46% had abnormal glucose levels. 16% of patients (93/573) were morbidly obese (BMI > 30) and 64% (292/573) were overweight.ConclusionThe incidence of AAAs in 65–75-year-old men is similar to international figures. This study confirms that screening for hyperlipidaemia, hypercholesterolaemia, obesity and hypertension may be worthwhile in all males over 55 years, while AAA screening should be reserved for 65–75-year-old Irish males.     

Prevalence of Abdominal Aortic Aneurysms in Patients Undergoing Coronary Artery Bypass

p = 0.0001). Ten patients had an AAA greater than 5.0 cm in size (5.2%). Logistic regression identified age ≥65 years and smoking as significant risk factors for AAA in the CABG population. The higher prevalence of AAA in CABG patients was confirmed by a case-control analysis of 73 age-matched patients. This study provides the first convincing evidence that the prevalence of AAA is higher in patients undergoing CABG than in the control population in Vermont. Consideration should be given to screening patients for AAA who are undergoing CABG, particularly older, smoking males.     

The incidence of hypomagnesaemia following abdominal aortic aneurysm surgery

IntroductionMagnesium is important for cardiac function. Hypomagnesaemia is associated with a higher incidence of arrhythmias and poorer outcomes in cardiac surgery. No studies have investigated the incidence or impact of postoperative hypomagnesaemia after abdominal aortic aneurysm (AAA) surgery. We aim to assess the incidence of hypomagnesaemia after AAA repair in our population.MethodsRetrospective analysis was performed of patients who underwent elective AAA surgery at a single vascular centre. The last 110 patients undergoing open or endovascular AAA repair were identified. The hospital pathology system was used to identify the immediate postoperative serum magnesium levels as well as patient demographics and admission details. Hypomagnesaemia was defined as serum magnesium of <0.7mmol/l.ResultsA total of 211 patients were studied and there were 3 deaths. Of the patients included, 101 underwent open elective AAA repair and 110 underwent endovascular repair. In the elective open repair group, 73 patients (73%) were hypomagnesaemic. In the endovascular repair group, 35 (32%) had hypomagnesaemia. A t-test showed a statistically significant difference in hypomagnesaemia between the open and endovascular groups (p<0.001).ConclusionsAAA surgery is associated with a high incidence of postoperative hypomagnesaemia, which is significantly greater among open repair patients. This is likely to have an effect on cardiac activity and lead to cardiac complications such as arrhythmias and poorer postoperative outcomes, especially in the open AAA repair subgroup. This stresses the importance of serum magnesium and cardiac monitoring in the postoperative phase. A prospective study is proposed to further investigate these findings, and their potential implications on perioperative morbidity and mortality.     

Low Quality of Life Prior to Screening for Abdominal Aortic Aneurysm: A Possible Risk Factor for Negative Mental Effects

The objective of this study was to evaluate the effect on quality of life (QOL) of screening for abdominal aortic aneurysm (AAA) in a population-based AAA screening program. Twenty-four patients with screening-detected AAA and 45 controls with normal aortic diameter were studied in a prospective, controlled, population-based study. Prior to and 12 months after the ultrasonography examination, all participants completed Short-Form 36 and at 12 months, 10 AAA-specific questions were added. Comparisons were made between the two groups (AAA patients and controls), within each group, and between the groups and norms for the general Swedish population in the same age interval. Our results showed that screening for AAA results in impairment of QOL among those who have the disease and who suffered a low QOL prior to screening. Among those who had an age-adjusted normal QOL prior to screening and who were found to have the disease, and among those who were found to have normal aortas, no negative effect on QOL was observed. Thus, low QOL before screening is a possible risk factor for negative mental effects of diagnosing an AAA by screening.     

Screening and ultrasound surveillance of large abdominal aortic aneurysms do not improve suitability for endovascular repair

OBJECTIVE: The effect of population screening for abdominal aortic aneurysm (AAA) disease on morbidity and mortality has been comprehensively studied and reported. However, the effect of early AAA detection on suitability for endovascular aneurysm repair (EVAR) remains unknown. Considering the importance of such an effect on future health economics, we sought to assess the possible effect of AAA ultrasound surveillance on suitability for EVAR. METHODS: This was a prospective cohort study. From January 2002 to August 2003, consecutive AAA patients selected for open elective repair were placed into one of two groups according to mode of presentation. The first group included patients referred from a local well-established AAA ultrasound screening and surveillance program (ultrasound surveillance [AAA-S] group). The second group included patients referred from neighboring unscreened regions with incidentally diagnosed AAA (incidental [AAA-I] group). All patients underwent preoperative computed tomographic angiography. By using three-dimensional reconstruction software, computed tomographic images were assessed by two blinded observers for suitability for EVAR by using the criteria for a modular endovascular device. RESULTS: Of 74 patients included in the study, 41 were in the AAA-S group, and 31 were in the AAA-I group. The median aneurysm diameter was 72.3 mm (range, 50.7-83.7 mm) for AAA-I and 65 mm (range, 50.7-79.2 mm) for AAA-S (P < .47). Suitability for EVAR was 41% in the AAA-S group and 45% in the AAA-I group (P < .47). CONCLUSIONS: Early detection and surveillance of AAA does not seem to increase suitability for EVAR. Suitability for EVAR seems to be determined early on in an aneurysm's life. On the basis of current device technology, referral for intervention from an AAA surveillance program may need to be initiated at a size well below 5.5 cm if an increase in EVAR suitability is to be expected.     

Ultrasound screening for abdominal aortic aneurysm in medicare beneficiaries

Ultrasound screening for abdominal aortic aneurysm (AAA) has been shown to be beneficial and cost-effective for men aged 65-74. However, most screening studies have been conducted in Europe and Australia, where attendance for screening was higher than the single large U.S. study involving only veterans. The prevalence of AAA in the U.S. general population is not well defined, nor is the best method of recruitment for screening. Letters of invitation for a free screening ultrasound for AAA were sent to 30,000 randomly selected Medicare beneficiaries from the hospital referral region of three university-affiliated hospitals without restriction by age, gender, or comorbidity. Attendance for screening was calculated by age, gender, and travel distance to the screening center. Telephone calls to a random sample of nonresponders were made to determine the reason for failure to attend. Prevalence of AAA by ultrasound and known risk factors for AAA (e.g., age, gender, smoking status) were determined. The attendance rate was 7% (2,005). Attendance was greater with male gender (p < 0.01), younger age (p < 0.05), and decreased travel distance to the screening center (p < 0.05). The primary reasons for failure to attend included incorrect address or vital status, poor health, and lack of interest. Prevalence of previously undetected AAA was 2.8% in men and 0.2% in women. AAA was predicted by smoking status and male gender (p < 0.01 for each). Unselected invitation of Medicare beneficiaries for ultrasound screening for AAA results in a low attendance and low yield of AAA. The prevalence estimates from this study may not reflect the entire Medicare population given the low attendance and may reflect the healthy habits of those most interested in screening. Patients should be selected for screening based on their suitability for repair if an AAA is found as well as their risk factors for AAA. The best method of recruitment for screening of those most at risk for AAA in the United States remains to be determined.     

SCREENING FOR ABDOMINAL AORTIC ANEURYSMS IN WESTERN AUSTRALIA

A study of ultrasound screening for abdominal aortic aneurysms (AAA) was performed. During a 6 month period, 1225 men and women aged 60–80 years were screen at a variety of community venues. Screening was well received by the public and logistically simple to perform. Thirty-three AAA were detected with sizes between 30 and 81 mm. In the 60–80 year age group, the prevalence of (AAA) > 30 mm in diameter was 4.7% in men and 0.35% in women, and the prevalence of AAA > 50mm was 0.6% in men and 0.17% in women. Cigarette smoking, but not hypertension or diabetes, was found to be a significant risk factor for AAA. This study confirms that screening for AAA is feasible and yields high prevalence rates in major population centres.