Lisette van Dam

Cost-effectiveness of MRI for diagnosing recurrent ipsilateral DVT 3 47 with an abnormal CUS (scenario 2) would be the most expensive strategy (1-year health care costs of €1529), because of high false-positive rates. Notably, the most and least expensive strategy differed for only €320, which is a relatively limited difference. Cost-effectiveness The estimated total 1-year health care costs of each diagnostic scenario were plotted against the predicted mortality per 10,000 patients ( Figure 4 and Table 3 ). Strategies at the bottom left of the figure are optimal, with low costs and low mortality. The diagnostic strategy that treats all patients had the lowest predicted mortality (1 per 1029 patients), but with highest estimated total health care costs. Four diagnostic scenarios were on the efficient frontier and thus potentially the most cost-effective strategies: CDR and D-dimer testing followed by CUS (positive/negative/inconclusive) and MRDTI (scenario 10), CUS (positive/negative/ inconclusive) followed by MRDTI (scenario 7), CUS (normal/abnormal) alone (scenario 2) and the treat all scenario. All other strategies were dominated, with either higher health care costs or higher mortality. Of the four scenarios on the efficient frontier, diagnostic scenario 10 has the lowest estimated costs of on average €1219 per patient with a predicted mortality of about 1 per 573 patients. Compared to this scenario 10, diagnostic scenario 7 increases average costs by €45 per patient and reduces mortality to 1 per 609 patients. The associated ICER for scenario 7 versus 10 is 0.4 million euros per prevented death. Scenario 2 further increases average costs by €266 per patient and decreases the predicted mortality to 1 per 737 patients. Here, the associated ICER of scenario 2 versus 7 is 0.9 million euros per prevented death. In the treat all scenario the average cost per patient further increases with €475 compared to scenario 2, while the estimated mortality decreases to 1 per 1029 patients. The associated ICER of the treat all scenario versus scenario 2 is 1.2 million euros per prevented death. For an acceptability threshold of 0.5 to 2 million euros per prevented death, scenario 10 is discarded, because scenario 7 provides lower mortality at acceptable costs (as 0.4 < 0.5 million). Thus, scenarios 7 and 2 and the treat all scenario remain as potentially optimal strategies (as 0.5 < 0.9 < 1.2 < 2 million).