Cost effectiveness of diagnosis of deep vein thrombosis in symptomatic patients

The most widely used noninvasive test for deep vein thrombosis is Doppler ultrasonographic imaging of the lower extremities. The best evaluated of the noninvasive approaches are ascending contrast venography, impedance plethysmography, Doppler ultrasonography with B-mode imaging. Economic evaluation is aimed at helping decision makers to reach their goal of maximizing the health of the population served, subject to the available resources.

The data that provided the basis for this cost effectiveness analysis were derived from a prospective study of approximately 500 patients referred to a regional thromboembolism program with a first episode of clinically suspected deep vein thrombosis. The application of cost effectiveness analysis to the diagnosis of deep vein thrombosis is readily accomplished using cost minimization. This cost effectiveness technique makes it possible to rank the diagnostic approaches from "worst" to "best", with the best approach defined as that which accomplishes the desired health effect at minimum cost. Effectiveness (health benefit) may be defined in this context as the number or proportion of patients with deep vein thrombosis correctly identified by objective testing or, the number or proportion in whom treatment was correctly withheld.

Clinical diagnosis is cost ineffective; $1,590,784 Canadian, $2,624,220 US. Outpatient diagnosis using noninvasive testing was the most cost effective. Serial Doppler ultrasonography is more costly ($618,265 Canadian, $1,326,180 US) than serial impedance plethysmography ($527,165 Canadian, $1,052,880 US). Combined Doppler ultrasonography and serial impedance plethysmography offers a less costly strategy ($551,065 Canadian, $1,124,580 US) than serial ultrasonography alone.

Objective testing is mandatory. Outpatient testing is preferred, avoiding unnecessary hospital admissions. Noninvasive testing is the most cost effective. The most widely used test, serial Doppler ultrasonography, is less cost effective than serial impedance plethysmography. The combined approach of initial Doppler ultrasonography followed by serial impedance plethysmography combines the advantage of an initial ultrasound image with less costly serial impedance plethysmography.