You will be provided with the titles and abstracts of a collection of medical RCT reports studying a clinical question -- for instance, the efficacy of an intervention on some medical outcome. Please write a few sentences synthesizing the findings of these reports, which could serve as a conclusion section for a systematic review article. Your response should not include any other text. The RCT reports are below.



Title 1:
The Multicentre Aneurysm Screening Study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial.
Abstract 1:
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.
                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.
                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.
                Our results provide reliable evidence of benefit from screening for abdominal aortic aneurysms.


Title 2:
Influence of screening on the incidence of ruptured abdominal aortic aneurysm: 5-year results of a randomized controlled study.
Abstract 2:
From family medical practices 15775 men and women aged 65-80 years were identified and randomized into two groups: one group was invited for ultrasonographic screening for abdominal aortic aneurysm (AAA), and the other acted as age- and sex-matched controls. Of the 7887 invited for screening 5394 (68.4 per cent) accepted. AAA was detected in 218 (4.0 per cent overall and 7.6 per cent of men). Aortic surgery was offered to the screened group if certain criteria were met and no patient died from rupture who was fit for operation and accepted elective treatment. The incidence of rupture was reduced by 55 per cent in men in the group invited for screening, compared with controls. The incidence of rupture in women was low in both groups.


Title 3:
Screening for abdominal aortic aneurysm: lessons from a population-based study.
Abstract 3:
To test the acceptability of screening and to identify modifiable risk factors for abdominal aortic aneurysm (AAA) in men.
                A trial of ultrasound screening for AAA in a population-based random sample of men aged 65-83 years, and a cross-sectional case-control comparison of men in the same sample.
                12,203 men who had an ultrasound examination of their abdominal aorta, and completed a questionnaire covering demographic, behavioural and medical factors.
                Prevalence of AAA, and independent associations of AAA with demographic, medical and lifestyle factors.
                Invitations to screening produced a corrected response of 70.5%. The prevalence of AAAs (> 30 mm) rose from 4.8% in men aged 65-69 years to 10.8% in those aged 80-83 years. The overall prevalence of large (> 50 mm) aneurysms was 0.69%. In a multivariate logistic model Mediterranean-born men had a 40% lower risk of AAA (> 30 mm) compared with men born in Australia (odds ratio [OR], 0.6; 95% CI, 0.4-0.8), while ex-smokers had a significantly increased risk of AAA (OR, 2.3; 95% CI, 1.9-2.8), and current smokers had even higher risks. AAA was significantly associated with established coronary and peripheral arterial disease and a waist:hip ratio greater than 0.9; men who regularly undertook vigorous exercise had a lower risk (OR, 0.8; 95% CI, 0.7-1.0).
                Ultrasound screening for AAA is acceptable to men in the likely target population. AAA shares some but not all of the risk factors for occlusive vascular disease, but the scope for primary prevention of AAA in later life is limited.
There is evidence of a significant reduction in mortality from AAA in men aged 65 to 79 years who undergo ultrasound screening. There is insufficient evidence to demonstrate benefit in women. The cost effectiveness may be acceptable, but needs further expert analysis. These findings need careful consideration in judging whether a co-ordinated population-based screening programme should be introduced.