Validation of the LET classification

Introduction

Acute thrombus removal therapies may reduce post-thrombotic syndrome in certain deep venous thrombosis patients. The LET classification is designed to identify patients at high risk for developing post-thrombotic syndrome in the acute phase using thrombus location and extent. This study evaluates the use of the LET classification to predict post-thrombotic syndrome in a cohort of patients after deep venous thrombosis.

Methods

A cohort of 660 deep venous thrombosis patients was invited to participate and fill out a questionnaire with Quality of life questionnaires, basic information, a modified self-assessment version of the Villalta scale for post-thrombotic syndrome and potential confounders. Original data on thrombus extension was available, and the LET classes were determined. Obtained information was analysed using ANOVA and in a multiple logistic regression model to correct for confounders. All different LET classes were compared to post-thrombotic syndrome occurrence, post-thrombotic syndrome prediction and disease specific quality of life scores (VEINES-Sym/Qol).

Results

Three hundred and fifteen patients responded, and in 309 a post-thrombotic syndrome score was distilled. LET I,II,III ( n = 63) had an odds ratio of 3.4(1.2–9.2) for predicting severe post-thrombotic syndrome, and LET II ( n = 17) had an odds ratio of 5.1(1.3–20.8) compared to LET class I ( n = 97). Both the VEINES-Sym and VEINES-Qol score were significantly lower for LET I,II,III compared to LET I, and LET II compared to LET I.

Conclusion

The LET classification can be used to classify patients according to acute thrombus location and extent. Extensive and centrally located (LET I,II,III) deep venous thrombosis showed the highest probability in developing severe post-thrombotic syndrome and lower disease specific quality of life.

Feasibility of identifying deep vein thrombosis characteristics with contrast enhanced MR-Venography

Purpose

To assess the feasibility of identifying deep vein thrombosis characteristics with contrast enhanced magnetic resonance venography.

Materials and Methods

A total of 53 cases of deep vein thrombosis extending in and/or above the common femoral vein were evaluated by 4 independent observers (2 expert, 2 novice) using pre-determined characteristics to determine the thrombosis present to be acute, sub-acute or old. If present, chronic remnants of a previous deep vein thrombosis were reported. Additionally these image qualifications were compared to the reported duration of complaints.

Results

In all cases all observers were able to qualify the thrombosis. The interobserver agreement between the experts was excellent (kappa 0.97) and good between expert and novice (kappa 0.82). Thrombosis identified as acute had an average duration of complaints of 6,5 (2–13) days, sub‐acute 13 (8–18) days and old 22 (15–32) days.

Conclusion

Qualification of thrombosis as acute, sub-acute or old and identification of chronic remnants of DVT with CE-MRV using routinely identifiable characteristics is feasible and reproducible with good to excellent interobserver agreement.

Viilaita Scale: Goals and Limitations

The post-thrombotic syndrome (PTS) is a common, debilitating complication following deep venous thrombosis. PTS is a syndrome for which it has been difficult to provide a clear definition. PTS was defined as chronic venous signs/symptoms after a deep venous thrombosis. A number of scales are available to diagnose PTS, but there is a strong need for standardization. The Villalta scale was chosen as the standardized PTS scale. The Villalta scale has been validated in several studies and shows good correlation with generic and disease-specific quality of life scales. The inter-observer rate between study nurses and physicians was shown to be very good. Furthermore, the scale shows good discriminative properties among the different severity groups of PTS. The Villalta scale is useful for use in randomized controlled trials and it allows pooling of data from different studies. The Villalta scale should undergo further validation on intra-rater reliability. Ongoing randomized controlled trials will further validate the Villalta scale for use in PTS.