Comparison of four strategies for diagnosing deep vein thrombosis: A cost-effectiveness analysis

PURPOSE: Four strategies for the diagnosis of deer vein thrombosis have bee n validated recently. The strategies use various combinations of assessment of a patient's clinical probability of having deep venous thrombosis, seri al lower limb venous compression ultrasonography, and measurement of plasma D-dimer levels. We compared the cost-effectiveness of these diagnostic str ategies. MATERIALS AND METHODS: We performed a formal cost-effectiveness analysis us ing a decision-analysis model. Outcomes considered were costs per patient, 3-month quality-adjusted survival, number of lives saved per 1,000 patients , and incremental costs per quality-adjusted life-year(QALY) gained. RESULTS: Under baseline conditions, with a 24% prevalence of deep vein thro mbosis in tested patients, the effectiveness of all strategies was similar (4.6 to 4.8 lives saved per 1,000 patients managed). The most expensive str ategy was serial ultrasound (repeat ultrasound on day 7 in all patients wit h a normal initial ultrasound) at a cost-effectiveness of $10,716 per addit ional QALY. Performing a repeat ultrasound only in patients with an elevate d D-dimer level (serial ultrasound with D-dimer) was somewhat less expensiv e at $10,281 per additional QALY. Taking clinical probability into account by repeating ultrasound only in patients with an intermediate clinical prob ability of deep vein thrombosis (risk-based serial ultrasound) yielded furt her savings and cost $10,090 per additional QALY. The least expensive and m ost cost-effective option was to perform D-dimer as the initial test, follo wed by a single ultrasound if the D-dimer level was abnormal, and by phlebo graphy in patients with a normal ultrasound and a high clinical probability of deep vein thrombosis (D-dimer with risk-based single ultrasound) at $8, 897 per additional QALY. This strategy allowed a 17% reduction in increment al costs compared with the most expensive algorithm and reduced resource co nsumption (70 ultrasound procedures per 100 patients managed vs 130 to 170 with the other diagnostic strategics). CONCLUSIONS: Combining clinical probability and D-dimer with a single ultra sound in the diagnostic workup of patients with possible deep vein thrombos is is highly cost-effective, allowing a reduction in costs and resource use without any substantial increase in mortality. Serial ultrasonography is l ess cost-effective. (C) 2001 by Excerpta Medica, Inc.