A randomized double-blind study of low-molecular-weight heparin (parnaparin) for superficial vein thrombosis: STEFLUX (Superficial ThromboEmbolism and Fluxum).

Background: Optimal doses and duration of low molecular weight heparin (LMWH) for the treatment of superficial vein thrombosis (SVT) is still uncertain. Objectives: To compare the efficacy and safety of different doses and durations of LMWH parnaparin for symptomatic lower limb SVT. Patients/methods: Outpatients with at least 4 cm long SVT of long or short saphenous veins or their collaterals were randomized to receive parnaparin either 8500 UI od for 10 days followed by placebo for 20 days (group A) or 8500 UI od for 10 days followed by 6400 UI od for 20 days (group B) or 4250 UI od for 30 days (group C) in a double blind fashion in 16 clinics. Primary outcome was the composite of symptomatic and asymptomatic deep vein thrombosis, symptomatic pulmonary embolism and relapse and/or symptomatic or asymptomatic SVT recurrence in the first 33 days with 60 day follow-up. Results: Among 664 patients, primary outcome occurred in 33/212 (15.6%), 4/219 (1.8%) and 16/217 (7.3%) subjects of groups A, B and C, respectively (B vs A: Absolute Risk Reduction-ARR-: 13.7%, 95% Confidence intervals-CI: 8-18.9% p<0.001; B vs C: ARR: 5.5%; 95% CI: 1.6-9.4% p=0.011; C vs A: ARR: 8.2%, 95% CI:2-14% p=0.012). During days 0-93 the event rate was higher in group A (22.6%) than either in group B (8.7%; p=0.001) or C (14.3%, p=0.034). No major haemorrhages occurred. Conclusions: Intermediate dose parnaparin for 30 days is superior to either 30 day prophylactic dose or 10 day intermediate dose for lower limb SVT treatment.