No abstract

The Netherlands Organization for Scientific Research.

To cite this article: ten Cate-Hoek AJ, Toll DB, Bü ller HR, Hoes AW, Moons KGM, Oudega R, Stoffers HEJH, van der Velde EF, van Weert HCPM, Prins MH, Joore MA. Cost-effectiveness of ruling out deep venous thrombosis in primary care versus care as usual. J Thromb Haemost 2009; 7: 2042-9.Summary. Background: Referral for ultrasound testing in all patients suspected of DVT is inefficient, because 80-90% have no DVT. Objective: To assess the incremental cost-effectiveness of a diagnostic strategy to select patients at first presentation in primary care based on a point of care D-dimer test combined with a clinical decision rule (AMUSE strategy), compared with hospital-based strategies. Patients/Methods: A Markov-type cost-effectiveness model with a societal perspective and a 5-year time horizon was used to compare the AMUSE strategy with hospital-based strategies. Data were derived from the AMUSE study (2005)(2006)(2007), the literature, and a direct survey of costs (2005)(2006)(2007). Results of base-case analysis: Adherence to the AMUSE strategy on average results in savings of €138 ($185) per patient at the expense of a very small health loss (0.002 QALYs) compared with the best hospital strategy. The iCER is €55 753($74 848). The cost-effectiveness acceptability curves show that the AMUSE strategy has the highest probability of being cost-effective. Results of sensitivity analysis: Results are sensitive to decreases in sensitivity of the diagnostic strategy, but are not sensitive to increase in age (range 30-80), the costs for health states, and events. Conclusion: A diagnostic management strategy based on a clinical decision rule and a point of care Ddimer assay to exclude DVT in primary care is not only safe, but also cost-effective as compared with hospital-based strategies.

BACKGROUND Point-of-care D-dimer tests have recently been introduced to enable rapid exclusion of deep venous thrombosis (DVT) without the need to refer a patient for conventional laboratory-based D-dimer testing. Before implementation in practice, however, the diagnostic accuracy of each test should be validated. METHODS We analyzed data of 577 prospectively identified consecutive primary care patients suspected to have DVT, who underwent 5 point-of-care D-dimer tests—4 quantitative (Vidas®, Pathfast™, Cardiac®, and Triage®) and 1 qualitative (Clearview Simplify®)—and ultrasonography as the reference method. We evaluated the tests for the accuracy of their measurements and submitted a questionnaire to 20 users to assess the user-friendliness of each test. RESULTS All D-dimer tests showed negative predictive values higher than 98%. Sensitivity was high for all point-of-care tests, with a range of 0.91 (Clearview Simplify) to 0.99 (Vidas). Specificity varied between 0.39 (Pathfast) and 0.64 (Clearview Simplify). The quantitative point-of-care tests showed similar and high discriminative power for DVT, according to calculated areas under the ROC curves (range 0.88–0.89). The quantitative Vidas and Pathfast devices showed limited user-friendliness for primary care, owing to a laborious calibration process and long analyzer warm-up time compared to the Cardiac and Triage. For the qualitative Clearview Simplify assay, no analyzer or calibration was needed, but interpretation of a test result was sometimes difficult because of poor color contrast. CONCLUSIONS Point-of-care D-dimer assays show good and similar diagnostic accuracy. The quantitative Cardiac and Triage and the qualitative Clearview Simplify D-dimer seem most user-friendly for excluding DVT in the doctor's office.

The rule can safely exclude DVT in primary care patients suspected of DVT, irrespective of age, gender and history of DVT.