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Evaluates the incidence of deep venous thrombosis (DVT) occurring as a consequence of long flights. Absence of cardiovascular disease and drug use in low-risk subjects; Use of ultrasound scans to diagnose DVT after the flights; Absence of DVT on low-risk groups; Comparison of the incidence of DVT between subjects wearing stockings and those that do not.

Background: The LONFLIT1+2 studies have established that in high risk subjects after long flights (> 10 hours) the incidence of deep venous thrombosis (DVT) is between 4% and 6%. The LONFLIT4 study was designed to evaluate the control of edema and DVT in low-medium risk subjects. The aim of this study was to evaluate edema and its control with specific stockings (ankle pressure between 20 and 30 mm Hg) in long-haul flights. The first part of the study included flights lasting 7-8 hours and the second part included flights lasting 11-12 hours. Ultrasound scans were used to assess thrombosis before and after the flights and a composite edema score was used to evaluate edema and swelling. A group of patients with microangiopathy associated to edema (diabetes, venous hypertension, anti-hypertensive treatment) were also included to evaluate the preventive effects of stockings during flight. Part I: DVT evaluation: Of the 74 subjects in the stocking group and 76 in the control group (150), 144 completed the study. Dropouts were due to low compliance or traveling and connection problems. Age and gender distribution were comparable in the 3 groups as was risk factor distribution. In this part of the study there were no DVTs. Edema evaluation: The level of edema at inclusion was comparable in the two groups of subjects. After the flight there was an average score of 6.9 (1) in the control group. In the stocking group, the score was on average 2.3 (1), three times lower than in the control group (p<0.05). Part II: DVT evaluation: Of the 66 included subjects in the stocking group and 68 in the control group (134), 132 completed the study. Dropouts were due to low compliance or connection problems. Age and gender distribution were comparable in the two groups. In the stocking group no DVT was observed. In the control group, 2 subjects had a popliteal DVT and 2 subjects had superficial venous thrombosis (SVT); in total 4 subjects (6%) in the control group had a thrombotic... [ABSTRACT FROM AUTHOR]

The LONFLIT1/2 studies have established that in high-risk subjects after long (> 10 hours) flights the incidence of deep venous thrombosis (DVT) is between 4% and 6%. The LONFLIT4 study has been planned to evaluate the control of edema and DVT in low-medium-risk subjects. The aim of this study was to evaluate edema and its control with specific flight stockings, in long-haul flights. In the first part of the study 400 subjects at low-medium risk for DVT were contacted; 28 were excluded for several nonmedical problems; 372 were randomized into 2 groups to evaluate prophylaxis with stockings in 7-8-hour flights; the control group had no prophylaxis. Below-knee, Scholl, Flight Socks, producing 14-17 mm Hg of pressure at the ankle, were used in the treatment group. The occurrence of DVT was evaluated with high-resolution ultrasound scanning (femoral, popliteal, and tibial veins). Edema was assessed with a composite score based on parametric and nonparametric measurements. Part II: In this part of the study 285 subjects at low-medium risk for DVT were included and randomized into 2 groups to evaluate edema prophylaxis in 11-12-hour flights; the controls had no prophylaxis while the prevention group had below-knee, Scholl, Flight Socks (comparable to part I). Results. Part I: DVT evaluation. Of the 184 included subjects in the stockings group and 188 in the control group, 358 (96.2%) completed the study. Dropouts were due to compliance or connection problems. Age/sex distributions were comparable in the groups. Stockings Group: of 179 subjects (mean age 49; SD 7; M:F = 101:78), none had DVT or superficial thromboses. Control Group: of 179 subjects (mean age 48.4; SD 7.3; M:F = 98:81), 4 (2.2%) had a DVT. There were also 2 superficial thromboses. In total, 3.35% (6) subjects had a thrombotic event. The difference (p < 0.002) is significant. Intention-to-treat analysis detects 15 failures in the control group (9 lost + 6 thromboses) out of 188 subjects (7.9%) versus 5... [ABSTRACT FROM AUTHOR]