Fibrinogen as a risk factor for coronary heart disease in the scottish heart health study

In the Scottish Heart Health Study 5093 men and 4862 women had their fibrinogen (Clauss assay) measured at baseline (1984-87). Over the following eight years discharges from hospital with a diagnosis of myocardial infarction, coronary artery surgical operations and deaths ascribed to coronary heart disease (CHD) were recorded for all subjects. Fibrinogen was assessed as a risk factor for both all coronary events and for CHD death alone. Account was taken of baseline CHD status. Of the 3930 men without CHD at baseline, 194 had a coronary event, of whom 54 died due to CHD. Of the 1067 men with CHD already at baseline, 195 had a coronary event, of whom 76 died due to CHD. For women the corresponding numbers are 3760,69,11 and 992, 80 ,24. Age adjusted risk ratios by fibrinogen thirds were estimated from Cox regression models. Regardless of baseline status, men have about 40% higher risk in the middle third and nearly twice the risk in the upper third, compared to the lowest third. Women have somewhat different results depending upon baseline status. Those with baseline CHD have no elevated risk in the middle third, but 1.5-2 times the risk in the highest third, compared to the first. Women without baseline CHD have about 2.5 times the risk in the middle third and more than three times the risk in the highest third. Further adjustments for known coronary risk factors (smoking, blood pressure and cholesterol) reduce the risk ratios without entirely removing the effect of fibrinogen. There is no evidence of interaction between fibrinogen and these classical risk factors. These results add to the evidence that fibrinogen is both a primary and a secondary risk factor for CHD, in women as well as in men.