Cost-effectiveness of different screening strategies for abdominal aortic aneurysm

OBJECTIVE: The primary objective of this study was to develop a simulation model to assess the cost-effectiveness of different screening strategies for abdominal aortic aneurysms (AAAs) in men. METHODS: A systematic review of the literature was conducted for different screening strategies in terms of age (60, 65, or 70 years) and risk profiles (all men or specific high-risk groups) of the screened population, and rescreening after 5 or 10 years. These data were analyzed in a Markov simulation cohort model. RESULTS: The cost per life year gained for different screening strategies ranged from US 8,309 dollars to US 14,084 dollars and was estimated at US 10,474 dollars when 65-year-old men were screened once. Screening 60-year-old men was equally cost-effective, with the advantage of more life years gained. We demonstrated a trade-off between high prevalence of AAA and lower life expectancy, eliminating the expected benefits of screening high-risk groups such as smokers (US 10,695 dollars) or cardiovascular patients (US 10,392 dollars). Assuming general population utility resulted in a cost per quality-adjusted life year (QALY) gained of US 13,900 dollars, whereas a hypothetical 5% reduction in utility among men with a screening-detected AAA raised the cost per QALY gained to US 75,100 dollars. CONCLUSION: This Markov model, which was based on a systematic review of the literature, supplied information on the estimated cost-effectiveness of different screening strategies. Screening men for AAA may be cost-effective in the long-term. Different screening strategies and quality-of-life effects related to screening for AAA need to be evaluated in future clinical studies.     

Mass screening on abdominal aortic aneurysm in men aged 60 to 65 years in The Netherlands. Impact on life expectancy and cost-effectiveness using a Markov model.

OBJECTIVES: To predict the costs and effects on life expectancy of an AAA screening programme. METHODS: A Markov model was designed to compare the effects of a single screening for a cohort of men 60-65 years with the current no screening strategy. The following health states were distinguished: no AAA, unknown small AAA, follow-up small AAA, unknown large AAA, repaired AAA, rejected large AAA and death. Transition rates between the health states were simulated using cycle times of one year. Transition probabilities were derived from literature and a previous feasibility study. Incremental costs per life year saved were calculated. Sensitivity analyses and discounting for future effects were performed. RESULTS: The expected individual AAA costs for non-screening and AAA screening were euro; 196 and euro; 530 respectively. A difference of 3.5 months life expectancy was found in favour of screening leading to euro; 1176/life-year gained. Costs increased as compliance fell. With a discount rate of 4% the costs are euro; 2021/life-year gained. CONCLUSIONS: One-time ultrasonographic screening for AAA in men aged 60-65 years appears to be cost-effective.     

Decision-analytical model with lifetime estimation of costs and health outcomes for one-time screening for abdominal aortic aneurysm in 65-year-old men

BACKGROUND: Abdominal aortic aneurysm (AAA) causes about 2 per cent of all deaths in men over the age of 65 years. A major improvement in operative mortality would have little impact on total mortality, so screening for AAA has been recommended as a solution. The cost-effectiveness of a programme that invited 65-year-old men for ultrasonographic screening was compared with current clinical practice in a decision-analytical model. METHODS: In a probabilistic Markov model, costs and health outcomes of a screening programme and current clinical practice were simulated over a lifetime perspective. To populate the model with the best available evidence, data from published papers, vascular databases and primary research were used. RESULTS: The results of the base-case analysis showed that the incremental cost per gained life-year for a screening programme compared with current practice was 7760, and that for a quality-adjusted life-year was 9700. The probability of screening being cost-effective was high. CONCLUSION: A financially and practically feasible screening programme for AAA, in which men are invited for ultrasonography in the year in which they turn 65, appears to yield positive health outcomes at a reasonable cost.     

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.     

Randomized clinical trial of screening for abdominal aortic aneurysm in women

BACKGROUND: Screening for abdominal aortic aneurysm (AAA) is commonly restricted to men. Recent studies have indicated a possible increase in deaths due to ruptured AAA in women, and a higher rate of rupture in women than in men. The present report details results from a randomized controlled trial that assessed the effects of screening women for AAA. METHODS: Some 9342 women aged 65-80 years were entered into the trial and randomized to age-matched screen and control groups. A single ultrasonographic scan was offered to women in the screening arm of the study. Women with an AAA received follow-up scans, and were considered for elective surgery if certain criteria were met. RESULTS: The prevalence of AAA was six times lower in women (1.3 per cent) than in men (7.6 per cent). Over 5- and 10-year follow-up intervals, the incidence of rupture was the same in the screened and control groups of women. CONCLUSION: Screening women for AAA is neither clinically indicated nor economically viable.     

Lifetime gain related to cost of repair of ruptured abdominal aortic aneurysm in octogenarians.

OBJECTIVE: To report cost related to gained life years after repair of ruptured abdominal aortic aneurysms in patients aged 80 or older. DESIGN: A retrospective study based on prospectively registered data. PATIENTS AND METHODS: Fifty-three patients aged 80 or older were operated on for ruptured abdominal aortic aneurysm over a 20-year period from 1983 to 2002. Thirty-one (58%) patients had systolic BT <80 mmHg. Operative mortality (<30 days) and long-term survival were studied. The number of life-years gained from the operations was estimated. Based on diagnose related group (DRG) values, the cost of each gained life-year was calculated. RESULTS: The operative mortality was 47%. Long-term survival of those patients who survived the operation was similar to that of an age and sex matched population. The 53 operations resulted in 145 gained life-years, which leaves a mean survival of 2.7 years of all the patients and 5.2 years of those who survived the operation. The estimated cost per gained life year was euro6817. CONCLUSIONS: The operative mortality of ruptured abdominal aortic aneurysm remains high. The long-term survival of patients who survive the operation is acceptable. The price of each gained life-year is low, as compared to other established treatment modalities. Improved results with endovascular treatment may even decrease the cost per gained life year.     

Cost-effectiveness analysis of screening for abdominal aortic aneurysms based on five year results from a randomised hospital based mass screening trial.

BACKGROUND: The aim of this study was to estimate the cost effectiveness of screening for abdominal aortic aneurysm (AAA). MATERIAL AND METHODS: All 12,639 men born in the years 1921-1933 (aged 64-73) living in Viborg County, Denmark, were randomly allocated either to receive an invitation to abdominal ultrasound scanning for AAA or to be controls. Costs for screening and surveillance were assessed prospectively. Diagnosis Related Group (DRG) costs from 1999 were used concerning admissions with uncomplicated and complicated operations. Admissions for AAA surgery were retrospectively classified according to complications in patient records. RESULTS: Mean follow-up time was 52 months. 76.6% of invited men attended screening, and 191 (4.0%) had an AAA. As previously reported, the cumulative 5-year AAA-specific mortality in the invited group was significantly reduced by 67% compared to the control group (P = 0.003). The costs were estimated to be Euro 11.23 per scan. The costs per life-year saved were Euro 9057 (Euro 5872-20,063) after 5 years, and were expected to decrease to Euro 2708 (Euro 1758-6031) after 10 years and to Euro 1825 (Euro 1185-4063) after 15 years. CONCLUSION: Screening of 64-73 years old males in Denmark seems cost effective.     

Hospital costs and benefits of screening for abdominal aortic aneurysms. Results from a randomised population screening trial.

OBJECTIVES: to analyse the hospital costs and benefits of screening older males for abdominal aortic aneurysm (AAA). MATERIALS and METHODS: in 1994 a hospital-based screening trial of 12 658 65-73-year-old males was started. AAA >5 cm were referred for surgery. The remaining AAA were offered annual scans. Those with aortic ectasia were rescreened at 5 yearly intervals. AAA-operations and hospital AAA-related deaths were researched. The costs of screening, surveillance, and treatment were also registered. RESULTS: the attendance rate was 76%; of whom 191 (4.0%) had AAA. Mean observation time was 5.13 years. Sixty in the screened and 41 in the control group were operated (p=0.06), of which 7 and 27 respectively were operated as an emergency (p<0.001), and 6 and 19 respectively died due to AAA (p=0.009). The costs per scan were 83.50 DKK, 81 400 DKK per emergency operation (71 485 DKK after screening), and 117 000 DKK per emergency operation. The cost per prevented hospital death was 67 855 DKK, equivalent to approximately life year saved approx. 7540 DKK (GBP1=12 DKK). CONCLUSION: screening appears to reduce hospital AAA mortality and to be cost-effective.     

The influence of screening on the incidence of ruptured abdominal aortic aneurysms.

PURPOSE: The purpose of this study was to estimate the influence of a screening program on the incidence and mortality of ruptured abdominal aortic aneurysms (RAAAs). METHODS: The effects of screening on the incidence and death rate of RAAAs were investigated with a stepped wedge study design. RAAAs that occurred in the Huntingdon district were traced with an examination of all hospital records and community postmortem records. RESULTS: During the 5-year period from 1991 to 1996, 78 RAAAs occurred in the Huntingdon district: 62 in men and 16 in women. Eleven of the 62 men with RAAAs had been invited for screening. The incidence of RAAA in the invited group was 3.7 per 10,000 person-years (py; 95% confidence interval [CI], 1.5 - 7.3). In the noninvited group, the incidence was 7.3 per 10,000 py (95% CI, 5.3. - 9.2), a rate ratio of 0.51 (95% CI, 0.26 - 0.97). The mortality of rAAAs in the invited group was 3.0 per 10, 000 py (95% CI, 1.4 - 5.4) as compared with 5.4 per 10,000 py in the noninvited group (95% CI, 3.9 - 7.3), resulting in a rate ratio of 0. 55 (95% CI, 0.26 - 1.15). CONCLUSION: Screening for asymptomatic AAAs can reduce the incidence rate of RAAAs by 49% (95% CI, 3% - 74%).     

Implications of screening for abdominal aortic aneurysms on surgical workload

BACKGROUND: The Multicentre Aneurysm Screening Study (MASS) provided strong evidence for both the clinical benefit and the cost-effectiveness of a screening programme for abdominal aortic aneurysms (AAAs) in men. If a national screening programme for AAA were adopted in the UK, it would be expected to increase the elective and decrease the emergency surgical workload. METHODS: The MASS trial randomized 67,800 men aged 65-74 years to be invited to attend for ultrasonographic screening for AAA or to a control group that received no invitation. Predictions of elective and emergency surgical workload were made for a 20-year interval after the introduction of a screening programme for 65-year-old men, based on surgical rates observed in the MASS trial and national mortality statistics. RESULTS: For a district general hospital serving a population of 400,000, there was an estimated reduction from nine emergency operations per year before introduction of the screening programme to three emergency operations annually in men aged 65 years and over by the end of the 20-year interval, and an increase from 24 to 43 AAA operations overall. The corresponding estimated annual costs for all AAA surgery increased by 47 per cent, from pound 209,000 to pound 308,000. These results were not affected by changes in the underlying assumptions. CONCLUSION: The results support the expectation of very few emergency operations, and principally elective operations, being performed following the introduction of a screening programme. For a typical district general hospital, a screening programme would be expected to lead to two additional elective AAA operations per month, and to save 11 AAA-related deaths per year.     

Cost-effectiveness of conventional and endovascular repair of abdominal aortic aneurysms: results of a randomized trial

BACKGROUND: Two randomized trials have shown similar mid-term outcomes for survival and quality of life after endovascular and conventional open repair of abdominal aortic aneurysms (AAA). With reduced hospital and intensive care stay, endovascular repair has been hypothesized to be more efficient than open repair. The Dutch Randomized Endovascular Aneurysm Management (DREAM) trial was undertaken to assess the balance of costs and effects of endovascular vs open aneurysm repair. METHODS: We conducted a multicenter, randomized trial comparing endovascular repair with open repair in 351 patients with an AAA and studied costs, cost-effectiveness, and clinical outcome 1 year after surgery. In addition to clinical outcome, costs and quality of life were recorded up to 1 year in 170 patients in the endovascular repair group and in 170 in the open repair group. Incremental cost-effectiveness ratios were estimated for cost per life-year, event-free life-year, and quality adjusted life-year (QALY) gained. Uncertainty regarding these outcomes was assessed using bootstrapping. RESULTS: Patients in the endovascular repair group experienced 0.72 QALY vs 0.73 in the open repair group (absolute difference, 0.01; 95% confidence interval [CI], -0.038 to 0.058). Endovascular repair was associated with additional euro 4293 direct costs (euro 18,179 vs euro 13.886; 95% CI, euro 2,770 to euro 5,830). Most of the bootstrap estimates indicated that endovascular repair resulted in slightly longer overall and event-free survival associated with respective incremental cost-effectiveness ratios of euro76,100 and euro 171,500 per year gained. Open repair appeared the dominant strategy in costs per QALY. CONCLUSION: Presently, routine use of endovascular repair in patients also eligible for open repair does not result in a QALY gain at 1 year postoperatively, provides only a marginal overall survival benefit, and is associated with a substantial, if not prohibitive, increase in costs.     

Implications of Attendance Patterns in Northern Ireland for Abdominal Aortic Aneurysm Screening

Introduction

Evidence supports the introduction of an abdominal aortic aneurysm (AAA) screening programme. The aims of this study were to estimate future disease patterns and to determine the effect of the proportion attending on the programme’s cost-effectiveness.

Patients and methods

The results of the local AAA screening programme were reviewed. Ultrasonic infrarenal aortic diameter of 30 mm was considered aneurysmal. Projected population numbers from the Department of Health and current disease prevalence were used to estimate future number of potential patients. The Multi-centre Aneurysm Screening Study (MASS) Markov model was used to calculate an incremental cost-effectiveness ratio (ICER) and 95% uncertainty intervals (UI), using a 30-year time horizon and 3.5% per annum discount, to determine the effect of attendance.

Results

Men were recruited from August 2004 to May 2010. 13316 were invited for a scan and 5931 (44.5%) attended. 321 AAA were diagnosed, giving a prevalence of 5.4%, while 27 large AAA (0.46%) were repaired. The annual incidence of AAA until 2021 will range from 441 to 526, with an incidence of 40–48 large AAA, with both showing a gradual increase with time. Using this attendance rate, the ICER was calculated at £2350 per life-year gained (95% UI: £1620–£4290), or £3020 per quality-adjusted life-year gained (95% UI: £2080–£5500).

Conclusions

The prevalence of disease in this local AAA screening was similar to other studies. The low attendance will result in many AAA being missed, but will not impact greatly on the long-term cost-effectiveness.     

Elective Versus Ruptured Abdominal Aortic Aneurysm Repair: A 1-Year Cost-Effectiveness Analysis

Abdominal aortic aneurysm (AAA) is a life-threatening condition with an overall mortality of 80%. It predominantly affects men 65-74 years of age and is caused by focal distension of the main blood vessel in the abdomen. Most patients go undetected until their aneurysm ruptures. Controversy surrounds the most appropriate form of screening for AAA. Currently, screening is only carried out selectively in patients with peripheral vascular disease. Some patients have their AAA detected incidentally, whilst ultrasound examination of the abdomen is carried out for other indications. These patients have the opportunity to undergo surveillance or elective surgery. The mortality rate of emergency surgical intervention following rupture (50%) is far worse in comparison to that of patients undergoing planned intervention under specialist vascular surgeons (5%). Despite improvements in outcomes from elective intervention for AAA as a result of specialisation, the overall mortality from this condition remains very high (80%) as the commonest presentation of an AAA is rupture. Screening all men aged 65-74 years is considered too costly in the current economic climate. However the cost difference between elective repair and emergency repair of AAA must be considered given that the outcome from elective AAA repair is far superior to that following ruptured AAA repair. Our objective was to retrospectively collect costs and outcomes of elective and emergency AAA repair in order to carry out a cost-effectiveness analysis. Four multiprofessional teams in accident and emergency, operation theatres, intensive care, and surgical wards at the Kent and Canterbury Hospital were selected from health-care professionals including doctors, managers, nurses, and clerical staff with the purpose of obtaining costs. Detailed cost data collection sheets were prepared to calculate costs, which included staff costs, consumables including drugs, intravenous fluids, equipment, investigations, laundry, catering, and stationery. An inventory of costs per item was obtained, and the total cost was calculated from the number of items used. Outcomes were measured in terms of survival. The total costs of emergency AAA repair were ￡96,700.69, with a cost per life saved of ￡24,175.17. The total cost of elective AAA repair was ￡76,583.22, with a cost per life saved of ￡5,470.23. Emergency intervention for AAA was found to cost five times more than a planned intervention per life saved per year.     

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).     

The Long-term Benefits of a Single Scan for Abdominal Aortic Aneurysm (AAA) at Age 65

AIM: To investigate the efficacy of a single ultrasonic scan at age 65 to identify patients at risk from ruptured abdominal aortic aneurysm (AAA). METHOD: A total of 6058 men aged 64-81 were recruited to a randomised trial, and 3000 were invited to attend a single screening test. An additional population of 1011 men was offered screening as they reached age 65. If a normal aorta was identified in this sub-group, further scans were offered at two-yearly intervals. Follow up and treatment of those identified as having an aortic dilatation of 3 cm or greater was undertaken. All subject groups were monitored for deaths occurring over the study period, and date and cause of death were recorded. RESULTS: A total of 2212 men attended screening in the randomised trial; the overall compliance was 74%, and prevalence of AAA was 7.7%. Compliance decreased, and prevalence increased, with age. Mortality from ruptured AAA was reduced by 68% at 5 years (screened group compared to the age-matched control population), and by 42% in the study arm (screened and refusers) compared with controls. The benefit persisted at ten years (53% and 21% respectively). Of the uncontrolled sample of 1011 men offered a scan at age 65, 681 attended and 649 of these were found to have a normal aortic diameter; re-screening demonstrated new aneurysm development in 4% over ten years. The aortic diameters of the new AAAs were under 4 cm and would therefore have a low risk of rupture.1 Mortality from rupture in all those with an initially normal aortic diameter was low, at 1 case per 1000 scans over ten years. CONCLUSION: Screening once for AAA at age 65 can identify the majority of AAA that are of clinical significance and can identify a large population at low risk from rupture who do not require surveillance. This policy has been effective when combined with selective treatment in reducing the risk of rupture for ten years in those who attend the screening programme.     

A quantitative analysis of the costs and benefits of prostate cancer screening

The present study attempts to quantitate in an economically and clinically meaningful manner the cost and cost-effectiveness of prostate cancer screening and subsequent treatment, including complications from that treatment. Outcome data from large prostate cancer screening trials using prostate specific antigen (PSA) and digital rectal examination (DRE) and PSA alone were used to construct the screening model. The benefit of screening is expressed in years of life saved by screening, which is calculated by comparing the survival rate of men with prostate cancer to the survival rate of men in the general population. The cost of screening, treatment, and complications were estimated using the Medicare data base and published reports on the cost, morbidity and mortality for radical prostatectomy. The cost per year of life saved by prostate cancer screening with PSA and DRE was $2339-3005 for men aged 50-59, $3905-5070 for men aged 60-69, and $3574-4627 overall for men aged 50-69. The cost per year of life saved by prostate cancer screening with PSA alone for men aged 50-70 was $3822-4956. A sensitivity analysis demonstrates that the cost per year of life saved by prostate cancer screening will not change substantially even if the assumptions in this model have been underestimated or overestimated by 100%. This study quantifies only those parameters which can be reliably compared in concrete terms such as dollars, treatment impact on survival, published complication rates and published treatment costs. Using this type of analysis, prostate cancer screening appears to be a cost-effective intervention. However, the issue of whether prostate cancer screening is cost-effective will be decided definitively only when randomized, controlled trials are available to quantify the costs and benefits of prostate cancer screening.Prostate Cancer and Prostatic Diseases (2001) 4, 138-145.     

Trends in mortality and hospital admission rates for abdominal aortic aneurysm in England and Wales, 1979-1999

BACKGROUND: The aim of this study was to investigate trends in population-based mortality, hospital admission and case fatality rates for abdominal aortic aneurysm (AAA) from 1979 to 1999. METHODS: This was an analysis of routine statistics from 79 495 death certificates in England and Wales and 3217 hospital inpatient admissions in the Oxford Region. RESULTS: Mortality rates for all AAAs increased between 1979 and 1999 from 13 to 25 per million in women and from 80 to 115 per million in men. Admission rates increased in the same time interval from three to 22 admissions per million per year in women, and from 52 to 149 per million per year in men. Case fatality rates for all non-ruptured AAAs that were operated on decreased from 25.8 to 9.0 per cent and for all ruptured AAAs from 69.9 to 54.4 per cent. CONCLUSION: Mortality rates and hospital admission rates for AAA rose in men and even more so in women between 1979 and 1999. Perioperative mortality for ruptured AAA declined a little during the study but nonetheless was still very high at the end. This reinforces the importance of detecting and treating AAA before rupture occurs.     

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.     

Final follow‐up of the Multicentre Aneurysm Screening Study (MASS) randomized trial of abdominal aortic aneurysm screening

Background:

The long‐term effects of abdominal aortic aneurysm (AAA) screening were investigated in extended follow‐up from the UK Multicentre Aneurysm Screening Study (MASS) randomized trial.

Methods:

A population‐based sample of men aged 65–74 years were randomized individually to invitation to ultrasound screening (invited group) or to a control group not offered screening. Patients with an AAA (3·0 cm or larger) detected at screening underwent surveillance and were offered surgery after predefined criteria had been met. Cause‐specific mortality data were analysed using Cox regression.

Results:

Some 67 770 men were enrolled in the study. Over 13 years, there were 224 AAA‐related deaths in the invited group and 381 in the control group, a 42 (95 per cent confidence interval 31 to 51) per cent reduction. There was no evidence of effect on other causes of death, but there was an overall reduction in all‐cause mortality of 3 (1 to 5) per cent. The degree of benefit seen in earlier years of follow‐up was slightly diminished by the occurrence of AAA ruptures in those with an aorta originally screened normal. About half of these ruptures had a baseline aortic diameter in the range 2·5–2·9 cm. It was estimated that 216 men need to be invited to screening to save one death over the next 13 years.

Conclusion:

Screening resulted in a reduction in all‐cause mortality, and the benefit in AAA‐related mortality continued to accumulate throughout follow‐up. Registration number: ISRCTN37381646 ( http://www.controlled‐trials.com ). Copyright © 2012 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.     

Late results concerning feasibility and compliance from a randomized trial of ultrasonographic screening for abdominal aortic aneurysm

BACKGROUND: The study was an update at 10 years of a randomized trial of the efficacy of screening for abdominal aortic aneurysm (AAA). The extent of benefit, feasibility and compliance were examined, and reasons why this intervention may fail a proportion of those screened were identified. METHODS: A total of 6058 men aged 65 years and over were randomized to a group invited to attend ultrasonographic screening or to a control group. The mortality rate from AAA in the two arms of the trial was compared using a Poisson model. Analyses were by intention to treat. RESULTS: There was a 21 per cent reduction in mortality rate from AAA over the 10-year follow-up (relative risk 0.79 (95 per cent confidence interval 0.53 to 1.40)). The observed relative mortality reduction peaked at 4 years with a 52 per cent reduction in the study group. Eighteen of 24 AAA deaths in the study group were among those who did not attend the first screen, or failed to comply with the follow-up protocol. CONCLUSION: A greater awareness of the benefits of full participation in a screening programme could provide a larger and sustained mortality reduction.