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).

Screening men for abdominal aortic aneurysm: 10 year mortality and cost effectiveness results from the randomised Multicentre Aneurysm Screening Study.

OBJECTIVES: To assess whether the mortality benefit from screening men aged 65-74 for abdominal aortic aneurysm decreases over time, and to estimate the long term cost effectiveness of screening. DESIGN: Randomised trial with 10 years of follow-up. SETTING: Four centres in the UK. Screening and surveillance was delivered mainly in primary care settings, with follow-up and surgery offered in hospitals. PARTICIPANTS: Population based sample of 67 770 men aged 65-74. INTERVENTIONS: Participants were individually allocated to invitation to ultrasound screening (invited group) or to a control group not offered screening. Patients with an abdominal aortic aneurysm detected at screening underwent surveillance and were offered surgery if they met predefined criteria. MAIN OUTCOME MEASURES: Mortality and costs related to abdominal aortic aneurysm, and cost per life year gained. RESULTS: Over 10 years 155 deaths related to abdominal aortic aneurysm (absolute risk 0.46%) occurred in the invited group and 296 (0.87%) in the control group (relative risk reduction 48%, 95% confidence interval 37% to 57%). The degree of benefit seen in earlier years of follow-up was maintained in later years. Based on the 10 year trial data, the incremental cost per man invited to screening was pound100 (95% confidence interval pound82 to pound118), leading to an incremental cost effectiveness ratio of pound7600 ( pound5100 to pound13,000) per life year gained. However, the incidence of ruptured abdominal aortic aneurysms in those originally screened as normal increased noticeably after eight years. CONCLUSIONS: The mortality benefit of screening men aged 65-74 for abdominal aortic aneurysm is maintained up to 10 years and cost effectiveness becomes more favourable over time. To maximise the benefit from a screening programme, emphasis should be placed on achieving a high initial rate of attendance and good adherence to clinical follow-up, preventing delays in undertaking surgery, and maintaining a low operative mortality after elective surgery. On the basis of current evidence, rescreening of those originally screened as normal is not justified. Trial registration Current Controlled Trials ISRCTN37381646.

The place of screening in the management of abdominal aortic aneurysm.

UNLABELLED: The present method of management of Abdominal Aortic Aneurysms (AAA) is ineffective in preventing AAA rupture. 5000 people still die of AAA in the UK each year. Improvements in surgery can only reduce the mortality in the minority who reach hospital following chance detection, and then only by a few percent. Screening, with detection in the community and planned treatment can reduce the mortality of the disease by 58%. Screening programmes for AAA have recently been approved for men aged 65 years, in both the UK and the USA. The proposed UK National Screening Programme is outlined briefly. CONCLUSION: If the aim of treatment is to reduce the mortality of the disease as a whole, resources would be better spent on screening programmes for AAA, rather than developing increasingly sophisticated operative techniques that could only reduce the overall death from AAA by a few percent.

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).

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.

Screening for abdominal aortic aneurysms: the effects of age and social deprivation on screening uptake, prevalence and attendance at follow-up in the MASS trial.

UNLABELLED: OBJECTIVES/SETTING: The effectiveness of screening programmes may be improved by knowledge of factors affecting screening uptake, disease prevalence and attendance for follow-up. Data from the Multicentre Aneurysm Screening Study (MASS) are used to examine the influences of age and social deprivation in the context of screening for abdominal aortic aneurysms (AAAs). METHODS: In the MASS trial, a population-based sample of 34,000 men aged 65 to 74 received an invitation to screening. The associations of attendance at screening with age, social deprivation and season of the year when invited to attend were investigated using logistic regression analysis. Similar analyses were performed for AAA prevalence and attendance at recall scans. RESULTS: Compared with men aged 65-69, those aged 70-74 were less likely to attend screening (79% vs 81%), had increased prevalence of AAA (6% vs 4%) and were less likely to attend for follow-up (79% vs 84%). Compared with those in the least deprived quartile, those in the most deprived quartile also were less likely to attend (75% vs 85%), had increased prevalence (6% vs 4%) and were less likely to attend for follow-up (80% vs 83%). Season showed no significant association with attendance at initial screening. CONCLUSIONS: Higher age and social deprivation are associated with both poorer attendance at screening and follow-up, and having an AAA. This highlights the importance of promoting screening programmes, particularly to the more deprived populations.

Abdominal aortic aneurysm and gastrointestinal disease: should synchronous surgery be considered?

BACKGROUND: Abdominal aortic aneurysm (AAA) is relatively common in an age group in which other abdominal pathologies have an increasing incidence. The co-existence of an aneurysm with a second intra-abdominal pathology presents a difficult management problem for the surgeon. Synchronous aortic and gastrointestinal surgery is often avoided due to the perceived higher risk of infection of the vascular prosthesis. METHODS: Cases of synchronous AAA repair with a second gastrointestinal/biliary procedure were identified from the operative records of a single vascular surgeon working in a district general hospital. RESULTS: Eight cases were identified over a 10-year period, comprising 3 large bowel resections, 2 cholecystectomies and 3 upper gastrointestinal operations as the second synchronous procedure. No graft infections were recorded in this group and there was one death within 30 days. CONCLUSIONS: From our experience and a review of the available literature we conclude that synchronous aortic and gastrointestinal surgery should be considered when urgent surgery for both conditions is indicated.

The Multicentre Aneurysm Screening Study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial.

BACKGROUND: Opposing views have been published on the importance of ultrasound screening for abdominal aortic aneurysms. The Multicentre Aneurysm Screening Study was designed to assess whether or not such screening is beneficial. METHODS: A population-based sample of men (n=67800) aged 65-74 years was enrolled, and each individual randomly allocated to either receive an invitation for an abdominal ultrasound scan (invited group, n=33839) or not (control group, n=33961). Men in whom abdominal aortic aneurysms (> or =3 cm in diameter) were detected were followed-up with repeat ultrasound scans for a mean of 4.1 years. Surgery was considered on specific criteria (diameter > or =5.5 cm, expansion > or =1 cm per year, symptoms). Mortality data were obtained from the Office of National Statistics, and an intention-to-treat analysis was based on cause of death. Quality of life was assessed with four standardised scales. The primary outcome measure was mortality related to abdominal aortic aneurysm. FINDINGS: 27147 of 33839 (80%) men in the invited group accepted the invitation to screening, and 1333 aneurysms were detected. There were 65 aneurysm-related deaths (absolute risk 0.19%) in the invited group, and 113 (0.33%) in the control group (risk reduction 42%, 95% CI 22-58; p=0.0002), with a 53% reduction (95% CI 30-64) in those who attended screening. 30-day mortality was 6% (24 of 414) after elective surgery for an aneurysm, and 37% (30 of 81) after emergency surgery. INTERPRETATION: Our results provide reliable evidence of benefit from screening for abdominal aortic aneurysms.

Screening and management of asymptomatic popliteal aneurysms.

OBJECTIVES: To determine the prevalence of popliteal aneurysms in men to enable the case for screening and elective surgery to be assessed. SETTING: Scott Research Unit, St Richards Hospital, Chichester. METHODS: The popliteal arteries of 1074 men aged between 65 and 80 were scanned with ultrasound, aneurysmal vessels >1.5 cm diameter were rescanned 5 years later to assess their rate of expansion. RESULTS: 11 of 1074 patients screened had a popliteal aneurysm between 15 and 26 mm, a prevalence of 1.0%. Five years later no increase in aneurysm size had occurred and no related complications were reported. CONCLUSION: In men the low prevalence and complication rate of popliteal aneurysms in conjunction with the effective treatment of acutely thrombosed aneurysms provides evidence for conservative management but against screening asymptomatic popliteal aneurysms.

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.

Probabilities of progression of aortic aneurysms: estimates and implications for screening policy.

BACKGROUND: Screening for abdominal aortic aneurysm, and intervention with elective repair, can reduce the incidence of aneurysmal rupture by a half. If a screening programme is implemented, it is essential to determine appropriate follow up intervals for rescreening. This paper estimates probabilities of progression growth of aortic diameter to provide evidence for this. METHODS: Data were taken from 2342 men aged 65-80 screened in the Chichester randomised control trial, who have been followed up for an average of 11 years. Aortic diameter was modelled as a Markov process with four categories: <30 mm (normal), 30-44 mm, 45-54 mm, and > or =55 mm. Estimates of the probabilities of progressing to each higher category were obtained. RESULTS: The probabilities of progression increased with greater initial aortic diameter. The estimated rates/year were 0.018 (95% confidence interval 0.014 to 0.023), 0.16 (0.12 to 0.20), and 0.49 (0.35 to 0.70) respectively for moving up one category. The probabilities of moving from <30 mm to > or =55 mm were estimated as 1% in 5 years and 12% in 15 years, while the corresponding figures for moving from 45-54 mm to > or =55 mm were 91% and 99%. There were differences in rates of progression according to age, with men over 70 years having rates about three times those of men under 70. CONCLUSIONS: It seems unnecessary to follow up men with normal aortic diameter as they experience a low probability of reaching criteria for surgery even within 15 years. However, follow up intervals should be progressively shorter for those with greater aortic diameter, especially in those aged over 70. Active follow up, for example every 3 months, is appropriate for men with an aortic diameter of 45-54 mm.

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.