Accuracy of contralateral Villalta score to assess for pre‐existing chronic venous insufficiency in patients with unilateral deep vein thrombosis

Background International guidelines recommend using the Villalta score (VS) to diagnose the postthrombotic syndrome (PTS). However, a high proportion of PTS detected with VS could just reflect the presence of preexisting primary venous insufficiency (PVI). Furthermore, it is unclear whether the contralateral VS (cl-VS) can be used to assess for preexisting PVI. Objectives To estimate whether cl-VS can be used to assess for preexisting PVI, and to assess the proportion of PTS that could be attributable to preexisting PVI. Methods Subanalysis of the SOX multicenter randomized trial focusing on patients with a first unilateral proximal deep vein thrombosis (DVT) followed for up to 2 years. PVI was defined as a baseline cl-VS > 4, and PTS as VS > 4 in the leg ipsilateral to DVT starting 6 months after DVT. Results Among 680 patients, mean cl-VS remained stable over time: 1.23 (standard deviation [SD] ±2.49) at baseline and 1.17 (±2.20), 1.59 (±2.81), 1.54 (±2.50), 1.65 (±2.82), and 1.55 (±2.63) at the 1-, 6-, 12-, 18-, and 24-month visits, respectively. Baseline cl-VS and ipsilateral VS measured during follow-up were mildly correlated (Pearson correlation = 0.13-0.25). This association disappeared after subtracting the cl-VS measured at the same visit from the ipsilateral VS. Overall, 48.8% of patients developed PTS of whom 12.8% had baseline cl-VS > 4. Conclusion In our study of patients with a first unilateral proximal DVT, the proportion of patients with PTS who had a cl-VS > 4 is modest. However, cl-VS appears to be stable over time. Its assessment could constitute a simple way of documenting preexisting PVI and help to classify patients as having PTS.