Abstract 5064: Venous Thrombosis after Air Travel: Prevention with Aspirin vs Low-Molecular-Weight Heparin (lmwh) in High-Risk Subjects. A Prospective Study
LONFLIT studies have observed that in subjects at high-risk (HRS) for deep venous thrombosis (DVT) during/after long (>10 hours) flights, the incidence DVT (by ultrasound scans) may be between 4% and 6% (including subclinical thrombi), This study evaluated DVT prevention in HRS: 886 subjects were approached and 600 were included. They were divided into 3 groups and advised to use during the flights: a:exercise only (no pharmacological prophylaxis) b: aspirin (400 mg tablets, soluble aspirin; one dose daily for 3 days, starting 24 hours before flights) c: low-molecular-weight heparin (LMWH; enoxaparine - Lovenox - injected 2– 4 hours before flights. The single dose was weight-adjusted (1000 IU - equivalent to 0.1 ml per 10kg of weight). Subjects with possible problems due to aspirin or LMWH, using anticoagulants and other drugs (at risk of interactions) were excluded. High-resolotion ultrasound scans included femoral,popliteal and soleal veins and were performed within 24 hours after the second flight. The time separation between the two flights was <8 days (average 6.5;SD1.1). 458 subjects completed the two-flights study. Dropouts were due to low compliance or traveling/connections problems. Age/sex and risk distribution were comparable in the three groups. Mean age was 44.7 (range, 24 – 66; SD 7.1; 54% males). In the control group (160), there were 6.87% of subjects with DVT plus 2 superficial thromboses (SVT)(total events 8.1%). Of 142 subjects in the aspirin treatment group, there were 4.9% of subjects with DVT plus 3 SVTs (total 7% of subjects with a thrombotic event). In the LMWH group (156) there were no cases of DVT and 2 superficial thrombosis (1.28%); (P<0.002 in comparison with the other two groups). DVT was asymptomatic in 64% of subjects; D-dimer was elevated in 78% o subjects with events and in 28% of subjects without events. Mild gastrointestinal symptoms were reported in 15% of patients using aspirin. No side-effects were observed in the LMWH group. In conclusion, one dose of LMWH is an important option to consider for HRS during long-haul flights.