Comparison of three ultrasound methods of measuring the diameter of the abdominal aorta

Background: Three ultrasound methods of measuring the diameter of the abdominal aorta exist: the outer-to-outer (OTO) method, where callipers are placed on the outer layer of the aortic wall; the inner-to-inner (ITI) method, where callipers are placed on the inner layer of the aortic wall; and the leading edge-to-leading edge (LELE) method, where callipers are placed on the outer layer of the anterior wall and the inner layer of the posterior wall. The aim was to determine the variability of the three methods, differences between them, and the consequences on prevalence estimates. Methods: Some 127 consecutive patients with a small abdominal aortic aneurysm (AAA) were included. The maximal anteroposterior diameter was measured using the OTO, ITI and LELE methods by two vascular sonographers who were blinded to each other's measurements. The variability was described as the standard deviation. Results: The variability was 2.7 (95 per cent limits of agreements +/- 5.4) mmfor the OTO, 2.3 (+/- 4.6) mm for the ITI and 2.0 (+/- 4.0) mm for the LELE method. The corresponding coefficients of variability were 6.4, 6.1 and 5.0 per cent. The difference was 4.1mm between ITI and OTO (P &lt; 0.001), 2.0 mm between ITI and LELE (P &lt; 0.001), and 2.1mm between LELE and OTO (P &lt; 0.001). Conclusion: LELE measurement was the most reproducible method of measuring the abdominal aorta. All methods showed a high degree of variability.</p

Cost-effectiveness of the National Health Service Abdominal Aortic Aneurysm Screening Programme in England.

BACKGROUND: Implementation of the National Health Service abdominal aortic aneurysm (AAA) screening programme (NAAASP) for men aged 65 years began in England in 2009. An important element of the evidence base supporting its introduction was the economic modelling of the long-term cost-effectiveness of screening, which was based mainly on 4-year follow-up data from the Multicentre Aneurysm Screening Study (MASS) randomized trial. Concern has been expressed about whether this conclusion of cost-effectiveness still holds, given the early performance parameters, particularly the lower prevalence of AAA observed in NAAASP. METHODS: The existing published model was adjusted and updated to reflect the current best evidence. It was recalibrated to mirror the 10-year follow-up data from MASS; the main cost parameters were re-estimated to reflect current practice; and more robust estimates of AAA growth and rupture rates from recent meta-analyses were incorporated, as were key parameters as observed in NAAASP (attendance rates, AAA prevalence and size distributions). RESULTS: The revised and updated model produced estimates of the long-term incremental cost-effectiveness of £5758 (95 per cent confidence interval £4285 to £7410) per life-year gained, or £7370 (£5467 to £9443) per quality-adjusted life-year (QALY) gained. CONCLUSION: Although the updated parameters, particularly the increased costs and lower AAA prevalence, have increased the cost per QALY, the latest modelling provides evidence that AAA screening as now being implemented in England is still highly cost-effective

Cost-effectiveness of screening for abdominal aortic aneurysm in the Netherlands and Norway

Background: The aim of this study was to determine the cost-effectiveness of ultrasound screening for abdominal aortic aneurysm (AAA) in men aged 65 years, for both the Netherlands and Norway. Methods: A Markov model was developed to simulate life expectancy, quality-adjusted life-years, net health benefits, lifetime costs and incremental cost-effectiveness ratios for both screening and no screening for AAA. The best available evidence was retrieved from the literature and combined with primary data from the two countries separately, and analysed from a national perspective. A threshold willingness-to-pay (WTP) of (sic)20 000 and (sic)62 500 was used for data from the Netherlands and Norway respectively. Results: The additional costs of the screening strategy compared with no screening were (sic)421 (95 per cent confidence interval 33 to 806) per person in the Netherlands, and the additional life-years were 0.097 (-0.180 to 0.365), representing (sic)4340 per life-year. For Norway, the values were (sic)562 (59 to 1078), 0.057 (-0.135 to 0.253) life-years and (sic)9860 per life-year respectively. In Norway the results were sensitive to a decrease in the prevalence of AAA in 65-year-old men to 1 per cent, or lower. Probabilistic sensitivity analyses indicated that AAA screening has a 70 per cent probability of being cost-effective in the Netherlands with a WTP threshold of (sic)20 000, and 70 per cent in Norway with a threshold of (sic)62 500. Conclusion: Using this model, screening for AAA in 65-year-old men would be highly cost-effective in both the Netherlands and Norway