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DVT study

Study assessing DVT resolution, recurrence and PTS

study will detect associations between characteristics present at baseline and outcomes identified during follow-up.
The study population mainly comprises outpatients but patients diagnosed with a DVT through this service, whilst an inpatient may be included in the study providing they meet the inclusion criteria

Researchers at the University Hospitals Bristol NHS Foundation Trust and the University of the West of England, UK, are investigating the thrombus morphology, evolution and resolution in a deep vein thrombosis (DVT) patient population, in order to identify the level of variation in response to anticoagulation treatment and provide more precise and quantitative disease characterisation in response to treatment.

In a protocol paper, ‘Deep vein thrombosis resolution, recurrence and post-thrombotic syndrome: a prospective observational study protocol’, published in BMC Hematology, the study authors also state that they will detect associations between characteristics present at baseline and outcomes identified during follow-up.

“This research into the response to treatment of lower limb DVT and predictive factors for DVT resolution, recurrence and PTS could inform a more tailored approach to anticoagulation therapy for the future management of DVT.”

This prospective, observational study will use duplex ultrasound to examine changes in thrombus characterisation, evolution and resolution over a two year period in patients with a confirmed DVT and seek associations between characteristics present at baseline and the outcomes of DVT resolution, recurrence and the development of post-thrombotic syndrome (PTS).

The study population mainly comprises outpatients but patients diagnosed with a DVT through this service, whilst an inpatient may be included in the study providing they meet the inclusion criteria:

  • Symptomatic adult patients aged between 18 and 85 years, diagnosed with a confirmed lower limb DVT on ultrasound
  • Diagnosis of lower limb DVT is made where partial or occlusive thrombus is present in any of the deep veins by either direct ultrasonic visualisation of intraluminal thrombus, lack of complete compressibility or absence of flow following distal compression.

The follow-up schedule comprises six visits for those participants with a first episode of DVT in the limb concerned at the following intervals: one week, one month, three months, six months, one year and two years. Participants with a history of previous ipsilateral DVT will undergo three follow up visits at one week, six months and two years.

At each visit participants undergo full compression ultrasound assessment of the complete lower limb venous tree from the level of the inguinal ligament to the ankle (common femoral vein, popliteal vein, peroneal veins, posterior tibial veins, anterior tibial veins, soleal veins, gastrocnemius veins, greater saphenous vein and short saphenous vein) to identify the presence or absence of residual or new DVT or superficial thrombophlebitis in each venous segment.

The presence of thrombus is recorded as occlusive or non-occlusive and details of recanalisation patterns are recorded in each segment. If the original diagnostic scan identifies the presence of thrombus in the iliac veins then the abdominal venous system is also scanned in full at each follow-up visit. In all cases, if flow in the common femoral vein on spectral Doppler ultrasound is not phasic with respiration, a full assessment of the external iliac vein, common iliac vein and inferior vena cava is undertaken using colour and spectral Doppler ultrasound.

Fifteen venous segments are assigned a thrombus score at each visit: inferior vena cava, common iliac vein, external iliac vein, common femoral vein, profunda femoris vein, proximal femoral vein, distal femoral vein, popliteal vein, peroneal veins, posterior tibial veins, anterior tibial veins, soleal veins, gastrocnemius veins, greater saphenous vein and short saphenous vein.

The thrombus load score is adapted from the updated reporting standards in venous disease from the Ad Hoc Committee on Reporting Standards of the Joint Council of the Society for Vascular Surgery and the North American Chapter of the International Society for Cardiovascular Surgery and a modified version of Haenan’s clot score.

Each venous segment is scored as follows:

  • 0=patent
  • 1=subsegmental, non-occlusive thrombus
  • 2=subsegmental, occlusive thrombus
  • 3=occlusive thrombus throughout segment

At each visit, a detailed clinical assessment is made of the leg in which the thrombosis is/was present and the patients’ symptoms, including pain, aching, heaviness, itching, cramp and paraesthesia are recorded using an interviewer-administered questionnaire. The Villalta Scale is used to quantify the symptoms of the burden of venous disease. The presence of oedema, teleangiectasias, reticular veins, varicose veins, hyperpigmentation, eczema, lipodermatosclerosis and ulceration are recorded according to the Clinical, Etiological, Anatomical and Pathophysiological (CEAP) classification system for classifying venous disease severity.

Details of the anti-coagulation treatment received by each patient in the study are collected as it is recognised that there are several different anti-coagulation therapies available and that variation in anti-coagulation regimes can occur depending on patient pathway, patient profile, patient choice and primary care follow-up. IN addition, participants’ compliance with compression stocking use is also recorded at each visit as ‘no use’, ‘occasional use’ or ‘routine use all day, every day’.

Any participant identified as having a recurrent DVT or an existing DVT that has extended at any point during follow-up is immediately reviewed by the rapid access thrombosis clinic. A recurrent DVT is diagnosed as the presence of a new thrombus either in the ipsilateral or contralateral leg or the presence of new thrombus on old thrombus in the same venous section as the original thrombosis, all of which are confirmed on Duplex ultrasound.

In total, 195 participants were recruited to the study and the first participants completed two years of follow up in February 2016. Data collection will continue until January 2018 with results expected to be published in late 2018.

“This research into the response to treatment of lower limb DVT and predictive factors for DVT resolution, recurrence and PTS could inform a more tailored approach to anticoagulation therapy for the future management of DVT,” the researchers note.

The article was edited from the original article, under the Creative Commons license.

To access this paper, please click here