Current classification tools for the diagnosis of chronic venous disease, including acute deep vein thrombosis (DVT) and post-thrombotic syndrome (PTS), include “redundant” elements that are unimportant to patients, according to an address delivered by Mark Meissner (Seattle, USA) at the International Union of Phlebology chapter meeting (UIP 2019; 25–27 August, Krakow, Poland). It was also emphasised that existing instruments do not account for some elements that are important to patients, such as venous claudication.
Speaking to delegates at UIP, Meissner opened: “If we look at current interventions for acute deep vein thrombosis (DVT), we have a number of high-profile recent successes such as the direct oral anticoagulant (DOAC) extended therapy for unprovoked or recurrent DVT, but we have also had some high-profile failures, such as the use of stockings for the prevention of post-thrombotic syndrome in the SOX trial and ATTRACT trial.”
Questioning the audience on why PTS prevention trials are failing while DVT prevention trials are proving successful, Meissner drew attention to the findings of the SOX and ATTRACT studies; in the SOX trial, 806 patients were randomised either to 30mm or 40mm knee-high stockings, or a placebo. Ultimately, there was no significant difference in the primary outcome of PTS—as defined by the Ginsberg score—between both groups (13% and 14% respectively). Results of the ATTRACT trial, which randomised patients to either catheter-directed thrombolysis or standard anticoagulation treatment, demonstrated a similar lack of difference.
While it is possible, Meissner argues, that these were not beneficial interventions—resulting in unsuccessful results across both trials—the instrument used for measuring a primary outcome of PTS may also present a “significant problem” for clinicians.
“There is essentially three instruments that have been used,” said Meissner, asserting the limitations of existing classification methods. The Ginsberg score, described by Meissner as a qualitative rather than quantitative tool, defines whether or not a patient has PTS based on yes or no answers to questions regarding pain and swelling, while the venous clinical severity score (VCSS), a patient questionnaire prone to “some error in observability,” is also considered to have problems.
The third and most commonly used instrument is the Villalta scale, which has been accepted as the gold standard in diagnosing PTS, even though it has “never been published”. Nevertheless, Meissner agrees that “it does include some of the elements we look for,” including pain, heaviness, oedema, skin induration, hyperpigmentation and redness. However, Meissner also highlighted the limitations of this classification tool, referring to the findings of a qualitative structure interview with 16 post-thrombotic patients on what is truly important for patients.
He said: “It was revealed that four domains are of primary importance; first and foremost is agonising discomfort. This was rarely described by patients as pain and did not fit very well into the Villalta instrument, and was usually described as heaviness, restlessness, pressure or venous claudication, but not typically as pain.”
Meissner also explained that while skin changes are important to patients suffering with a painful ulcer, all other forms of skin change—which represents four components of the Villalta scale—were “not important to patients at all”. Other areas that were considered important ranged from fluctuating heaviness and swelling to the fear of recurrence and loss of social interaction because of physical problems encountered as a result of chronic venous disease.
It was concluded, following this interview with patients, that the Villalta scale does not represent the full scope of typical post-thrombotic complaints or their importance to patients. In addition to this, studies presented at UIP 2019, including an investigation conducted by Imperial College London, UK (see below), underlined that the Villalta scale is not disease-specific and over-identifies mild PTS, which has little to no significant impact on a patient’s quality of life. This suggests that a more optimal instrument is required.
Meissner himself concluded: “Recent large randomised trials investigating the prevention of PTS have largely been negative; it’s certainly possible that these interventions are truly ineffective, but it’s equally likely that these clinical trials are flawed and probably one of the big reasons is the inappropriate outcome measures.”