External Validation of the Patient-Reported Villalta Scale for the Diagnosis of Postthrombotic Syndrome

INTRODUCTION:  The Villalta scale is the endorsed tool to diagnose and grade the severity of postthrombotic syndrome (PTS); however, assessing presence and severity of PTS is time-consuming and relies on both the clinician and patient's assessments. The patient-reported Villalta scale version 2 (PRV2) is a visually assisted form that enables patients to self-assess presence and severity of PTS. Herein, we report on external validation of this tool. METHODS:  We assessed the agreement and kappa values of PRV2 to diagnose and assess severity of PTS compared with the original Villalta score in a cohort of 181 patients (196 limbs) who participated in the SAVER pilot randomized control trial. Presence of PTS was defined as PRV2 ≥5 or a Villalta score ≥5. RESULTS:  PTS prevalence was 42% using PRV2 and 33% using the Villalta scale. The corresponding kappa and percentage agreement were 0.60 (95% confidence interval [CI]: 0.49-0.71) and 81% (95% CI: 76-87), respectively. Kappa values and percentage agreements between PRV2 and Villalta scale increased with increasing severity of PTS. The sensitivity of PRV2 to detect PTS of any severity was 84% (95% CI: 73-92) with a specificity of 79% (95% CI: 71-86). CONCLUSION:  We conclude that the PRV2 is an acceptable tool for diagnosing and grading the severity of PTS.