Long-term risk of venous thromboembolism recurrence after isolated superficial vein thrombosis

Background: Isolated superficial vein thrombosis (iSVT) (without concomitant deep vein thrombosis [DVT] or pulmonary embolism [PE]) is a frequent event, but available data on long-term outcomes are scarce and retrospective. Therefore, we aimed to determine prospectively the risk and type of venous thromboembolism (VTE) recurrence after iSVT and compare them with those of proximal DVT. Methods: Using data from the prospective, multicenter, observational, OPTIMEV study, we assessed, at 3 years and after anticoagulants were stopped, the incidence and the type of VTE recurrence (iSVT/DVT/PE) of patients with a first objectively confirmed iSVT without cancer (n = 285), and compared these with those of patients with a first proximal DVT without cancer (n = 262). Results: As compared with proximal DVT patients, iSVT patients had a similar overall incidence of VTE recurrence (5.4% per patient-year [PY] versus 6.5% per PY, adjusted hazard ratio [aHR] 0.9, 95% confidence interval [CI] 0.5-1.6), but iSVT recurred six times more often as iSVT (2.7% versus 0.6%, aHR 5.9, 95% CI 1.3-27.1) and 2.5 times less often as deep-VTE events (2.5% versus 5.9%, aHR 0.4, 95% CI 0.2-0.9). Varicose vein status did not influence the risk or the type of VTE recurrence. Saphenian junction involvement by iSVT was not associated with a higher risk of recurrence (5.2% per PY versus 5.4% per PY), but was associated with recurrence exclusively as deep-VTE events. Conclusion: In patients with a first iSVT without cancer, after stopping anticoagulants, the incidence of deep-VTE recurrence is half that of DVT patients, but the overall risk of recurrence is similar. Ssaphenian junction involvement seems to influence the risk of deep-VTE recurrence, whereas varicose vein status has no impact or a low impact on VTE recurrence.