Biases of Villalta scale in classifying post-thrombotic syndrome in patients with pre-existing chronic venous disease.

OBJECTIVE: The Villalta scale (VS) is a recommended and widely used clinical severity score for diagnosis and grading of post-thrombotic syndrome (PTS). However, patients with primary chronic venous disease (CVD) who have a history of deep venous thrombosis (DVT) may be classified as having PTS even though post-thrombotic disease is not actually present. The purpose of this study was to investigate the biases of the VS with use in patients with pre-existing CVD.

METHODS: This single-center, prospective, observational study included patients who were diagnosed with CVD during a 12-month period from 2016 to 2017. The VS and the Venous Clinical Severity Score (VCSS) were completed, and bilateral lower extremity venous duplex ultrasound studies were performed. The correlation of the VS with the VCSS was analyzed. Sensitivity, specificity, positive bias, and negative bias of the VS combined with a history of DVT were calculated. For patients in whom DVT developed during the study, the VS score was taken 12 months after the onset of DVT and compared with the score before DVT.

RESULTS: A total of 288 patients were included. The VS score correlated well with the VCSS, with a correlation coefficient of 0.86 (P < .001). The two scores changed similarly over time. The accuracy of the VS combined with a history of DVT was 94.1%, with a sensitivity of 71.4% and a specificity of 95.9%. The positive bias was as high as 42.3%, although the negative bias was 2.3%. The VS score decreased to a normal level during follow-up in 41.7% of the CVD patients in whom a new DVT developed (n = 12).

CONCLUSIONS: The use of the VS for defining PTS appeared to misclassify those with primary CVD and a history of DVT as having PTS by 42.3%. Using the VS at follow-up in patients with PTS and pre-existing CVD may be misleading. Re-evaluation of the results of previous studies that used the VS may be needed.