Inter-rater Agreement Between Professional-Rated and Patient-Rated Scores of the Villalta Scale for Evaluation of the Post-Thrombotic Syndrome

Within the two years following lower extremity deep vein thrombosis (DVT), between 35 and 56% of cases develop postthrombotic syndrome (PTS) [ 1 Wik H.S. Jacobsen A.F. Sandvik L. Sandset P.M. Prevalence and predictors for post-thrombotic syndrome 3 to 16 years after pregnancy-related venous thrombosis: a population-based, cross-sectional, case-control study. J. Thromb. Haemost. 2012; 10: 840-847https://doi.org/10.1111/j.1538-7836.2012.04690.x Crossref PubMed Scopus (69) Google Scholar , 2 Kahn S.R. Shrier I. Julian J.A. Ducruet T. Arsenault L. Miron M.J. et al. Determinants and time course of the postthrombotic syndrome after acute deep venous thrombosis. Ann. Intern. Med. 2008; 149: 698-707 Crossref PubMed Scopus (649) Google Scholar , 3 Roumen-Klappe E.M. den Heijer M. Janssen M.C. van der Vleuten C. Thien T. Wollersheim H. The post-thrombotic syndrome: incidence and prognostic value of non-invasive venous examinations in a six-year follow-up study. Thromb. Haemost. 2005; 94: 825-830https://doi.org/10.1160/TH05-03-0146 Crossref PubMed Scopus (97) Google Scholar , 4 Roumen-Klappe E.M. Janssen M.C. Van Rossum J. Holewijn S. Van Bokhoven M.M. Kaasjager K. et al. Inflammation in deep vein thrombosis and the development of post-thrombotic syndrome: a prospective study. J. Thromb. Haemost. 2009; 7: 582-587https://doi.org/10.1111/j.1538-7836.2009.03286.x Crossref PubMed Scopus (111) Google Scholar ]. PTS is characterized by eleven possible symptoms and signs, including pain, edema and venous ulcers [ [5] Villalta S. Assessment of validity and reproducibility of a clinical scale for the post thrombotic syndrome (abstract). Haemostasis. 1994; 24: 158a Google Scholar ]. PTS is reported to be moderate to severe in 3–10% of cases, but this can vary to a significant degree within patients during at least the first 2 years after DVT [ [2] Kahn S.R. Shrier I. Julian J.A. Ducruet T. Arsenault L. Miron M.J. et al. Determinants and time course of the postthrombotic syndrome after acute deep venous thrombosis. Ann. Intern. Med. 2008; 149: 698-707 Crossref PubMed Scopus (649) Google Scholar ]. Consequences of PTS include a reduction of quality of life (QoL) and associated patient and societal economic burdens [ [6] Caprini J.A. Botteman M.F. Stephens J.M. Nadipelli V. Ewing M.M. Brandt S. et al. Economic burden of long-term complications of deep vein thrombosis after total hip replacement surgery in the United States. Value Health. 2003; 6: 59-74https://doi.org/10.1046/j.1524-4733.2003.00204.x Abstract Full Text PDF PubMed Scopus (146) Google Scholar ]. The scientific standardization committee of the International Society on Thrombosis and Haemostasis has recommended the Villalta Scale [ [5] Villalta S. Assessment of validity and reproducibility of a clinical scale for the post thrombotic syndrome (abstract). Haemostasis. 1994; 24: 158a Google Scholar ] as the gold standard to assess PTS [ [7] Kahn S.R. Measurement properties of the Villalta scale to define and classify the severity of the post-thrombotic syndrome. J. Thromb. Haemost. 2009; 7: 884-888https://doi.org/10.1111/j.1538-7836.2009.03339.x Crossref PubMed Scopus (174) Google Scholar ]. The Villalta Scale includes a patient-rated symptoms subscale (five items) and professional-rated signs subscale (six items), both assessed at the same time at the outpatient clinic. This reduces the usability of the Villalta Scale in long-term follow-up and clinical trials, as hospital visits can be burdensome and costly. Self-assessment of PTS by patients using the Villalta Scale may be an alternative approach. Recently, Utne et al. (2016) [ [8] Utne K.K. Ghanima W. Foyn S. Kahn S. Sandset P.M. Wik H.S. Development and validation of a tool for patient reporting of symptoms and signs of the post-thrombotic syndrome. Thromb. Haemost. 2016; 115: 1-7https://doi.org/10.1160/TH15-04-0318 Crossref Scopus (32) Google Scholar ] tested whether visually assisted self-assessment of PTS using the Villalta Scale was valid and reliable. They found a very good agreement between the self-rated Villalta Scale score and the original (professional-rated) Villalta Scale score. However, this agreement was dependent on a visual aid, developed earlier for trial purposes by Kahn et al. [ [9] Kahn S.R. Partsch H. Vedantham S. Prandoni P. Kearon C. Definition of post-thrombotic syndrome of the leg for use in clinical investigations: a recommendation for standardization. J. Thromb. Haemost. 2009; 7: 879-883https://doi.org/10.1111/j.1538-7836.2009.03294.x Crossref PubMed Scopus (360) Google Scholar ], as agreement was only moderate (Kappa 0.60, 95% CI 0.48–0.72) for the self-administration of the Villalta Scale without this aid.