Many long-term studies have reported on associations of plasma fibrinogen concentration with cardiovascular disease, but few have been large enough to provide reliable estimates in different circumstances. Moreover, most published prospective studies have related disease risk only to baseline values of plasma fibrinogen (which can lead to substantial underestimation of any risk relationships) and have corrected only for baseline values of possible confounding factors (which can lead to residual biases). By appropriate combination of data from individual participants from all relevant prospective studies in a systematic ‘meta-analysis’, with correction for regression dilution, the Fibrinogen Studies Collaboration aims to characterize more precisely than has previously been possible the strength and shape of the age- and sex-specific associations of plasma fibrinogen with coronary heart disease (and, where data are sufficient, with other vascular diseases). It will also help to determine to what extent such associations are independent of possible confounding factors. A central database has been established containing data on plasma fibrinogen, sex and other potential confounding factors, age at baseline fibrinogen measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of fibrinogen and potential confounding factors has been sought to allow study-specific correction for regression dilution.
Synthesis of the available prospective studies of plasma fibrinogen has yielded information on each of 154,211 participants in 31 prospective studies. During approximately 1.38 million person-years of follow-up, there were 6944 first nonfatal myocardial infarctions or stroke events and 13,210 deaths, with moderately strong associations found between usual plasma fibrinogen level and the risks of CHD, stroke, other vascular mortality, and nonvascular mortality in a wide range of circumstances in healthy middle-aged adults.
These and other findings have now been published.