An economic evaluation of an abdominal aortic aneurysm screening program in Italy
ABSTRACT Abdominal aortic aneurysm (AAA) is defined as a localized dilatation of an aortic vessel. Though predominantly asymptomatic, it is a chronic degenerative condition associated with life-threatening risk of rupture. The early diagnosis of AAA, ie, before it ruptures, is therefore important; a simple, effective diagnostic method is ultrasound examination. To assess the benefit of screening in Italy, we developed a cost-effective Markov model comparing screening vs nonscreening scenarios.
A 13-health-states Markov model was developed to compare two cohorts of 65- to 75-year-old men: the first group undergoing screening for AAA by means of ultrasound (US), the second following the current practice of incidental detection. The following health states were distinguished: no AAA, unknown small AAA (3-3.9 cm), followed-up small AAA (1 year), unknown medium-sized AAA (4-4.9 cm), followed-up medium-sized AAA (6 months), unknown large AAA (>5 cm), elective repair, emergency repair, postelective-repair AAA, postemergency-repair AAA, rejected large AAA, and death. Transitions between health states were simulated by using 6-month cycles. Transition probabilities were derived from a literature review of relevant randomized controlled trial and from a screening program that is currently ongoing at San Martino Hospital in Genoa, Italy. The Italian National Health Service (NHS) perspective was adopted and incremental cost per life-year saved was calculated with a lifetime horizon; costs and health benefits were discounted at an annual rate of 3% from year 2 onward. Uncertainty surrounding the model inputs was tested by means of univariate, multivariate, and probabilistic sensitivity analyses.
Considering an attendance rate of 62%, the individual cost per invited subject was €60 (US $83.2); 0.011 additional quality adjusted life years (QALY) were gained per patient in the screened cohort, corresponding to an incremental cost-effectiveness ratio (ICER) of €5673/QALY (US $7870/QALY). The results were sensitive to some parameter variations but consistent with the base case scenario. They suggest that on the basis of a willingness-to-pay threshold of €50,000/QALY, screening for AAA is cost-effective, with a probability approaching 100%.
As in economic evaluations developed in other countries, such as the UK, Canada, and The Netherlands, setting up a screening program for AAA can be considered cost-effective from the Italian NHS perspective.
- SourceAvailable from: Paolo A Cortesi[Show abstract] [Hide abstract]
ABSTRACT: To estimate a value set for the calculation of Italian-specific quality-adjusted life years (QALYs), based on preferences elicited on EuroQol five-dimensional (EQ-5D) questionnaire health states using the time trade-off technique. The revised standard Measurement and Valuation of Health protocol was followed. Twenty-five health states, divided into three groups and given to 450 subjects, were selected to obtain 300 observations per state. Subjects aged 18 to 75 years were recruited to be representative of the Italian general adult population for age, sex, and geographical distribution. To improve efficiency, face-to-face interviews were conducted by using the Computer Assisted Personal Interviewing approach. Several random effects regression models were tested to predict the full set of EQ-5D questionnaire health states. Model selection was based on logical consistency of the estimates, sign and magnitude of the regression coefficients, goodness of fit, and parsimony. The model that satisfied the criteria of logical consistency and was more efficient includes 10 main effect dummy variables for the EQ-5D questionnaire domain levels and the D1 interaction term, which accounts for the number of dimensions at levels 2 or 3 beyond the first. This model has an R(2) of 0.389 and a mean absolute error of 0.03, which are comparable to or better than those of models used in other countries. The utility estimates after state 11111 range from 0.92 (21111) to -0.38 (33333). Italian utility estimates are higher than those estimated in the United Kingdom and Spain and used so far to assess QALYs and conduct cost-utility evaluations in Italy. A specific value set is now available to calculate QALYs for the conduction of health economic studies targeted at the Italian health care system.Value in Health 07/2013; 16(5):814-22. DOI:10.1016/j.jval.2013.04.008 · 2.89 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: INTRODUCTION: Abdominal aortic aneurysm (AAA) screening programmes reduce AAA-related mortality and are cost-effective. This study aims to assess the state and variability of AAA screening programmes worldwide. METHODS: Data were obtained from an international expert group convened at the 34th Charing Cross Symposium as well as government websites and published reports on screening programmes. RESULTS: Six countries are in the process of implementing national AAA screening programmes, with Italy still performing screening trials. There is wide variability in inclusion criteria between countries with the majority screening only men in their 65th year, however 3 programmes include women, 2 programmes only include patients with high cardiovascular risk, and 2 trials are also screening for hypertension and lower limb atherosclerosis. Surveillance intervals vary between screening programmes, with the most common regimen being to vary the surveillance interval depending upon aneurysm size, however the optimum surveillance interval in terms of decreasing mortality and cost effectiveness remains uncertain. DISCUSSION: International dissemination of current AAA screening programme outcomes is required to inform developing programmes about optimum screening intervals, benefits of surveillance of the subaneurysmal aorta, and screening for other cardiovascular disease.European journal of vascular and endovascular surgery: the official journal of the European Society for Vascular Surgery 01/2013; 45(3). DOI:10.1016/j.ejvs.2012.12.013 · 3.07 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Small abdominal aortic aneurysms (AAAs [3.0 cm-5.4 cm in diameter]) are monitored by ultrasound surveillance. The intervals between surveillance scans should be chosen to detect an expanding aneurysm prior to rupture. To limit risk of aneurysm rupture or excessive growth by optimizing ultrasound surveillance intervals. Individual patient data from studies of small AAA growth and rupture were assessed. Studies were identified for inclusion through a systematic literature search through December 2010. Study authors were contacted, which yielded 18 data sets providing repeated ultrasound measurements of AAA diameter over time in 15,471 patients. AAA diameters were analyzed using a random-effects model that allowed for between-patient variability in size and growth rate. Rupture rates were analyzed by proportional hazards regression using the modeled AAA diameter as a time-varying covariate. Predictions of the risks of exceeding 5.5-cm diameter and of rupture within given time intervals were estimated and pooled across studies by random effects meta-analysis. AAA growth and rupture rates varied considerably across studies. For each 0.5-cm increase in AAA diameter, growth rates increased on average by 0.59 mm per year (95% CI, 0.51-0.66) and rupture rates increased by a factor of 1.91 (95% CI, 1.61-2.25). For example, to control the AAA growth risk in men of exceeding 5.5 cm to below 10%, on average, a 7.4-year surveillance interval (95% CI, 6.7-8.1) is sufficient for a 3.0-cm AAA, while an 8-month interval (95% CI, 7-10) is necessary for a 5.0-cm AAA. To control the risk of rupture in men to below 1%, the corresponding estimated surveillance intervals are 8.5 years (95% CI, 7.0-10.5) and 17 months (95% CI, 14-22). CONCLUSION AND RELEVANCE: In contrast to the commonly adopted surveillance intervals in current AAA screening programs, surveillance intervals of several years may be clinically acceptable for the majority of patients with small AAA.JAMA The Journal of the American Medical Association 02/2013; 309(8):806-13. DOI:10.1001/jama.2013.950 · 30.39 Impact Factor