THE EFFECTS OF ALCOHOL ON COAGULATION AND FIBRINOLYTIC FACTORS - A CONTROLLED TRIAL

Light-to-moderate alcohol intake is associated with a reduced incidenc e of ischaemic cardiovascular events, whilst heavy alcohol intake can predispose individuals to stroke. Alcohol-induced changes in coagulati on and fibrinolysis may be relevant and are the subject of this contro lled trial of varying alcohol intake in 55 predominantly beer-drinking men. Following 4 weeks stabilization maintaining usual drinking habit s, participants were randomized to either continue usual alcohol intak e or to restrict alcohol by changing to low alcohol beer for 4 weeks. In a final 4 week period, they crossed over to low or usual alcohol in take, respectively. Comparing combined low and usual alcohol periods, an increase in mean weekly alcohol intake from 92 to 410 ml (mean dail y intake from 13 to 58 ml) was associated with a decrease in plasma fi brinogen (by 11%, P < 0.001) and platelet count (3%, P < 0.05), but in creases in factor VII (7%, P = 0.001), tissue plasminogen activator (t PA; 16%, P = 0.01) and plasminogen activator inhibitor-1 (PAI-1; 21%, P < 0.001). The ratio, tPA/PAI-1, fell from 0.50 to 0.44 (P = 0.02) co nfirming the relatively greater increase in PAI-1 , with alcohol consu mption. Two lipid-associated natural anticoagulants, tissue factor pat hway inhibitor and beta(2)-glycoprotein-I, did not change. The substan tial reduction in plasma fibrinogen with alcohol intake may well contr ibute to the apparent protection alcohol confers against ischaemic cor onary and cerebral events. The increase in factor VII and relatively g reater increase in PAI-1 than tPA with alcohol intake may attenuate th is benefit and indeed may sufficiently predispose individuals to throm bosis to contribute to the increased incidence of ischaemic stroke see n in heavier drinkers. The balance of anticoagulant and procoagulant a nd fibrinolytic effects in any individual may vary depending on quanti ty and type of alcoholic beverage ingested, as well as on genetic and other variables, all of which merit further study. (C) 1998 Rapid Scie nce Ltd.