A national NHS programme exists in England that offers screening for abdominal aortic aneurysm in men aged 65, with the aim of reducing deaths from aneurysm rupture.1 The key evidence underpinning the formulation of this policy was the results of the multicentre aneurysm screening study (MASS), funded by the Medical Research Council.2 More than 67 000 men aged 65-74 were recruited from four centres in the UK for this study and were randomised to either receive or not receive an invitation to screening. The results after 4 years’ follow-up showed a 42% relative risk reduction in mortality related to abdominal aortic aneurysm (absolute risk reduction from 0.33% to 0.19%). An economic evaluation indicated that the investment in screening was close to being acceptably cost effective, even in the short term.3 The evidence of clinical effectiveness was reinforced by a subsequent Cochrane Review—which estimated a 40% relative risk reduction (absolute risk reduction from 0.27% to 0.16%)—and then by results from MASS after 7 years’ follow-up.4 5 A formal long term economic model built on the MASS data indicated that abdominal aortic …