Assessing the contribution of fibrinogen in predicting risk of death in men with peripheral arterial disease

Background: Although fibrinogen is known to be an independent population-level risk factor for cardiovascular disease in healthy individuals, less is known about its value for individual-level risk prediction. Objectives: To assess the independent contribution of plasma fibrinogen to risk prediction in men with peripheral arterial disease. Patients and methods: We used data from the 785 men randomized to placebo in the Lower Extremity Arterial Disease Event Reduction (LEADER) trial. Men were followed at 6-monthly intervals up to 3 years, during which 116 patients died. Multivariable standard and pooled logistic regression were used to model odds of death in the next 3 years or in a 6-month interval. The c-statistic and predictiveness curves were used to assess improvement in predictive ability. Results: Fibrinogen measured at baseline was an independent predictor of all-cause mortality risk (adjusted odds ratio [OR] 1.44, 95% confidence interval [CI] 1.02-1.94, for a 1 g L-1 increase). Adding baseline fibrinogen to a set of other risk factors did not, however, substantially improve predictive ability. Similarly, fibrinogen measured at the start of a 6-month interval was independently associated with odds of death in the next 6 months (adjusted OR 1.65; 95% CI 0.96-2.73). Again, predictiveness curves with and without fibrinogen did not substantially differ, although the c-statistic increased by 0.011. Conclusions: Although fibrinogen was independently associated with both 6-month and 3-year mortality risk, individual-level risk prediction was not substantially improved by including fibrinogen in risk models.