as a risk factor for deep-vein thrombosis
M Den Heijer, T Koster,
Hj Blom, Gmj Bos, E Briet, Ph Reitsma, Jp Vandenbroucke , Fr
N Engl J Med 1996;
Background. Previous studies bave suggested
that hyperhomocysteinemia may be a risk factor for venous
thrombosis. To assess the risk of venous thrombosis
associated with hyperhomocysteinemia, we studied plasma
homocysteine levels in patients with a first episode of
deep-vein thrombosis and in normal control subjects.
Methods. We measured plasma homocysteine
levels in 269 patients with a first, objectively diagnosed
episode of deep-vein thrombosis and in 269 healthy controIs
matched to the patients according to age and sex.
Hyperhomocysteinemia was defined as a plasma homocysteine
level above the 95th percentile in the control group (18.5
µmol per liter).
Results. Of the 269 patients, 28 (10
percent) had plasma homocysteine levels above the 95th
percentile for the controls, as compared with 13 of the
controls (matched odds ratio, 2.5; 95 percent confidence
interval, 1 .2 to 5.2).The association between elevated
homocysteine levels and venous thrombosis was stronger among
women than among men and increased with age. The exclusion
of subjects with other established risk factors for
thrombosis (a deficiency of protein C, protein S, or
antithrombin; resistance to activated protein C; pregnancy
or recent childbirth; or oral-contraceptive use) did not
materially affect the risk estimates.
Conclusions. High plasma homocysteine levels
are a risk factor for deep-vein thrombosis in the general