Fibrinogen as a risk factor for coronary heart disease and mortality in middle-aged men and women: The Scottish Heart Health Study

Aims Fibrinogen was measured in 5095 men and 4860 men aged 40–59in a random population sample from 25 districts of Scotlandrecruited during 1984–87: the Scottish Heart Health Study.Fibrinogen was then related to the chance of fatal and non-fatalcoronary events and death from any cause during a subsequentfollow-up period of around 8 years. Methods and results Fibrinogen was measured by the Clauss assay.The effect of fibrinogen on coronary heart disease and deathwas assessed through age-adjusted means and Cox proportionalhazards regression models, accounting for age, cotinine (a measureof tobacco smoke inhalation) and 11 other major coronary riskfactors. Fibrinogen was found to be an important risk factorfor coronary heart disease in men and women, with and withoutpre-existing coronary heart disease. There appears to be a thresholdeffect, with those in the highest fifth of the distributionhaving a much increased risk. Estimated age- adjusted hazardratios by sex and pre-existing coronary heart disease groupfor the highest to lowest fifth of fibrinogen range between1·93 and 4·86. Fibrinogen is also important asa risk factor for coronary death and all-causes mortality, witha similar threshold effect. Comparing the two extreme fifths,the hazard ratios for coronary death are 3·01 and 3·42,and for all-cause mortality are 2·59 and 2·20,for men and women respectively. Adjustment for cotinine reducesthe hazard ratios, but further adjustment for the other 11 riskfactors has little effect for coronary heart disease events.After full adjustment there is a remaining significant (P<0·05)hazard ratio for coronary death and death from any cause andfor a coronary heart disease event for those free of coronaryheart disease at baseline, amongst men, comparing the highestto the lowest fifth. Conclusion Fibrinogen is a strong predictor of coronary heartdisease, fatal or non-fatal, new or recurrent, and of deathfrom an unspecified cause, for both men and women. Its effectis only partially attributable to other coronary risk factors,the most important of which is smoking.