Full Length ArticleRetrospective review on isolated distal deep vein thrombosis (IDDVT) — A benign entity or not?
Introduction
Isolated distal deep vein thrombosis (IDDVT) is a common variant of venous thromboembolism (VTE) which accounts for approximately 23%–59% of all deep vein thrombosis (DVT) [1]. The risk of pulmonary embolism (PE), a major comorbidity of VTE, was observed to be low in untreated patients with IDDVT with the CALTHRO study reporting a 1.6% incidence during a 3-month follow-up period [2]. Most studies, although not all [3], also reported lower VTE recurrence risk [4], [5], [6]. Hence, when occurring in isolation, IDDVT is generally considered to be more “benign” compared to proximal DVT and/or pulmonary embolism (PE).
Despite their frequent occurrence, the investigation and management of IDDVT are heterogeneous and there remains no standard of care [7], [8]. In fact, in some institutions, compression ultrasonography is limited to the proximal veins without extension to the distal veins, thus possibly leading to the under-diagnosis of distal vein thrombosis [9]. In addition, serial proximal ultrasound is not infrequently only reserved for high-risk patients [8]. The lack of standardised care is due to inconsistent findings in many aspects of IDDVT including immediate thrombotic complications such as proximal DVT extension and PE, and also late VTE recurrence. This is reflected by conflicting recommendations provided by different guidelines, with some recommending observation with serial ultrasonography in low to medium risk patients [10], while others recommending 3 months of upfront treatment [11].
Many ongoing studies, such as CACTUS [9] and TWISTER (NVT01252420), are focusing on the duration of anticoagulation after an acute event. However, there remains a paucity of studies evaluating long-term complications such as thrombosis recurrence and subsequent malignancy. Knowledge of these complications may assist in clarifying both the optimal treatment duration, and also the adequate clinical assessment required for the individual with an IDDVT.
We aim to review the real-life IDDVT management strategies in the warfarin era at two major tertiary hospitals in Northeast Melbourne, where whole leg ultrasound is routinely performed, as well as evaluate epidemiological risk factors and recurrence rates. This is a subset of a larger audit, which evaluated all types of VTE.
Section snippets
Methods
A retrospective analysis was conducted of consecutive patients presenting with VTE during an 18-month period, between July 2011 and December 2012, at two major tertiary teaching hospitals in Melbourne, Australia (Austin Health and Northern Health). Both the tertiary institutions are the only tertiary hospitals serving Northeast Melbourne with an estimated combined population of more than 1.5 million, and constitute the main referral centres for these areas. VTE-related presentations were
Results
A total of 1024 VTE events were identified during the 18-month study recruitment period, involving 1002 patients with 22 recurrent presentations within the period. Excluding patients with known active malignancy, superficial VTE, dural sinus thrombosis and portal vein thrombosis, 578 patients had major VTE (total of 586 events) while 164 patients (total of 166 events) had IDDVT, approximating 22% of all non-cancer VTE patients (Fig. 1). Seventy-seven and eighty-seven patients were affected in
Discussion
This retrospective population-based study reaffirms that IDDVT is relatively common (22% of all non-cancer related VTE), albeit less common than proximal VTE, which is similar to previous studies [1], [3]. The higher incidence compared to the Worcester study [3] is likely due to the routine use of whole-leg ultrasound study in Australia, which leads to increased IDDVT diagnosis.
Despite IDDVT being common, the management strategies remained diverse. Most patients (88%), however, did received
Conclusion
IDDVT patients in this retrospective observational cohort had a non-inferior rate of thrombosis recurrence and prospective malignancy detection, compared to major VTE, despite the lower overall thrombosis burden. This suggests that while the medical community generally considers IDDVT as a benign entity, the incidence of late complications such as recurrence and subsequent malignancies should not be neglected. Appropriate surveillance for these complications remains important in this population
Conflicts of interest
None to declare.
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