Jean Marie U-King-Im MBBS, Presenter: Nothing to Disclose

William Hollingworth PhD, Abstract Co-Author: Nothing to Disclose

Rikin A. Trivedi MBBS, Abstract Co-Author: Nothing to Disclose

Martin John Graves, Abstract Co-Author: Nothing to Disclose

Nagui Antoun, Abstract Co-Author: Nothing to Disclose

Jonathan Harvey Gillard MD, Abstract Co-Author: Nothing to Disclose

The optimal diagnostic strategy to image carotid stenosis remains controversial. Our main was to assess the long-term cost-effectiveness of five alternative diagnostic strategies for identification of severe carotid stenosis in recently symptomatic patients.

A decision-analytical model with Markov transition states was constructed. Data souces included a prospective study involving 167 patients who had screening Doppler ultrasound (DUS) , confirmatory contrast-enhanced MR angiography (CEMRA) and confirmatory digital subtraction angiography (DSA) as part of their diagnostic workup, individual patient data from the European Carotid Surgery Trial and other published clinical and cost data.

A ‘selective’ strategy whereby all patients receive DUS and CEMRA, only proceeding to DSA if the CEMRA is positive and the DUS is negative, was most cost-effective. This was both the cheapest imaging and treatment strategy ($35,205 per patient) and yielded 6.1590 QALYs; higher than three alternative imaging strategies. A ‘combination’ DUS and CEMRA strategy whereby all discordant DUS and CEMRA results are verified by DSA was fractionally more effective (6.1591 QALYs) but also more expensive ($35,476 per patient) as more patients receive DSA. Probabilistic sensitivity analysis demonstrated that there was less than a 10% probability that imaging with either DUS or DSA alone are cost-effective at the conventional $50,000 per QALY threshold. However, due to the uncertainty in the model inputs, we could not exclude the possibility that any of the three other strategies involving CEMRA would be the most cost-effective in actual practice.

DSA is not cost-effective in the routine diagnostic work-up of the majority of patients. Additional imaging in the form of CEMRA is recommended, with a strategy of ‘CEMRA and selective DUS review’ being shown to be the optimal imaging strategy. Definitive treatment decisions based on CEMRA alone may, however, be acceptable, especially if DSA is not readily available.

J.H.G.: This study was funded by a grant from the UK National Health Service Research and Development

U-King-Im, J, Hollingworth, W, Trivedi, R, Graves, M, Antoun, N, Gillard, J, Identifying Severe Carotid Stenosis in Symptomatic Patients prior to Carotid Endarterectomy: Long-term Analysis of Morbidity and Cost-effectiveness.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4407412.html