PB0900 - A Ten-Year Retrospective Evaluation of the Management of Iliofemoral Deep Vein Thrombosis in Australia

Background: Iliofemoral deep vein thrombosis (IFDVT) is associated with higher risk of adverse outcomes compared to more distal DVTs such as phlegmasia, recurrent thromboembolism and post-thrombotic syndrome (PTS).

Aims: To characterize the real-world management of IFDVT in an Australian population.

Methods: Retrospective evaluation of IFDVT managed at Northern Health, Victoria, Australia from January 2011 to December 2020. The analysis included demographics, risk factors, management and outcomes, with median follow-up 26 months. Results were compared to non-iliofemoral lower limb DVT (n=1793).

Results: A total of 376 IFDVT episodes (median age 69 years; 54.4% female (n=204)) were diagnosed. 61.6% (n=231) were provoked events, most commonly due to active malignancy (n=100, 26.7%), followed by immobility/injury (n=86, 22.9%). 27% (n=103) had a prior VTE. 25% (n=94) of patients had concomitant pulmonary embolism, while 9% (n=34) had bilateral DVTs. Seven cases were associated with May-Thurner syndrome, all were treated with catheter-directed thrombolysis, and five received iliofemoral stenting.
In the non-malignant cohort, IFDVT patients more often received warfarin treatment (51.1% vs 42.9%, p=0.008) and longer duration (8 vs 6 months, p< 0.001) or indefinite anticoagulation (29.0% vs 16.0%, p< 0.001) compared to other DVTs. VTE recurrence (2.7/100PY) (HR 0.84 95% CI: 0.56-1.25) and major bleeding (2.7/100PY) (HR 1.68, 95%CI: 0.88-3.23) were not significantly different between both groups. However, the 30-day all-cause mortality (5.1% vs 1.2%, p< 0.001) including death due to thrombosis (1.4% vs 0.4%, p=0.023) were more common with IFDVT. 35 patients (12.4%) reported PTS, including four patients with May-Thurner syndrome.
Malignant patients with IFDVT had comparable VTE recurrence rate (4.3/100PY, p=0.418) but higher major bleeding (12.4/100PY, p=0.044

Conclusion(s): While the VTE recurrence and major bleeding were comparable between patients with IFDVT and non-IFDVTs, mortality was higher in the former. This suggests a high-risk cohort that warrants careful assessment.