FLYING IS RISKIER IN PATIENTS WITH FVL AND/OR OC USE

Investigators in the Netherlands evaluatedthe effects of air travel versus long periods ofimmobilization on the ground on indicators ofclotting activation. Seventy-one patientswere divided into 4 groups: (1) patients withthe factor V Leiden (FVL) mutation, (2) patientswho used oral contraceptives (OCs), (3)patients with both risk factors, and (4)patients with neither risk factor. Three indicatorsof clotting were measured at baselineand before and after 3 interventions: an 8-hrplane flight, an 8-hr movie marathon, and 8 hrof a "daily life situation."

Thrombin-antithrombin complex was theindicator that exhibited the greatest increaseof ~30% after the flight, versus decreases of2% and 7.9% after the movie marathon andthe daily life situation, respectively. Highresponders for any of the indicators werefound in 17% of individuals after air travel, versus3% after the movie marathon and only 1%after the daily life situation.

The presence of FVL or OC use increasedthe likelihood of having elevated indicators,and the effect of combining both factorsappeared to be additive. The authors suggestedthat the low air pressure and/or lowoxygen level in planes during travel mayincrease the risk of clotting over thatobserved with immobilization on the ground.Risks appear to be higher in patients with FVLor OC use but are not completely negated inpatients with no risk factors. Two of the highestresponders in the study had neither of thestudied risk factors.

Dr. Garrett is a clinical pharmacist practitionerat Cornerstone Health Care in HighPoint, NC.