Context: Patients with suspected deep vein thrombosis (DVT) of the lower extremities are usually investigated with ultrasonography either by the proximal veins (2-point ultrasonography) or the entire deep vein system (whole-leg ultrasonography). The latter approach is thought to be better based on its ability to detect isolated calf vein thrombosis; however, it requires skilled operators and is mainly available only during working hours. No randomized comparisons are yet available evaluating the relative values of these 2 strategies.
Objective: To assess if the 2 diagnostic strategies are equivalent for the management of symptomatic outpatients with suspected DVT of the lower extremities.
Design, setting, and patients: A prospective, randomized, multicenter study of consecutive symptomatic outpatients (n = 2465) with a first episode of suspected DVT of the lower extremities who were randomized to undergo 2-point or whole-leg ultrasonography. Data were taken from ultrasound laboratories of 14 Italian universities or civic hospitals between January 1, 2003, and December 21, 2006. Patients with normal ultrasound findings were followed up for 3 months, with study completion on March 20, 2007.
Main outcome measure: Objectively confirmed 3-month incidence of symptomatic venous thromboembolism in patients with an initially normal diagnostic workup.
Results: Of 2465 eligible patients, 345 met 1 or more exclusion criteria and 22 refused to participate; therefore, 2098 patients were randomized to either 2-point (n = 1045) or whole-leg (n = 1053) ultrasonography. Symptomatic venous thromboembolism occurred in 7 of 801 patients (incidence, 0.9%; 95% confidence interval [CI], 0.3%-1.8%) in the 2-point strategy group and in 9 of 763 patients (incidence, 1.2%; 95% CI, 0.5%-2.2%) in the whole-leg strategy group. This met the established equivalence criterion (observed difference, 0.3%;95% CI, -1.4% to 0.8%).
Conclusion: The 2 diagnostic strategies are equivalent when used for the management of symptomatic outpatients with suspected DVT of the lower extremities.
Trial registration: clinicaltrials.gov Identifier: NCT00353093.