Do HMG-CoA reductase inhibitors affect fibrinogen?

OBJECTIVE: To review commonly used fibrinogen assay methods and the evidenc e demonstrating an association between fibrinogen and increased risk of cor onary artery disease and to review the current literature to determine and assess the impact of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase i nhibitors on fibrinogen. DATA SOURCES: Primary and review articles identified from a MEDLINE search (1966-December 1999); references obtained from these publications were subs equently reviewed for additional relevant articles. STUDY SELECTION AND DATA EXTRACTION: All articles were evaluated, and all r elevant information was included in this review. DATA SYNTHESIS: The Clauss method is currently the preferred method for det ermining plasma fibrinogen concentrations, due to its high degree of accura cy and precision. Furthermore, unlike immunologic methods, its reliability is unaffected by change in triglycerides. The effects of four HMG-CoA reduc tase inhibitors (atorvastatin, lovastatin, simvastatin, pravastatin) on fib rinogen have been revaluated. Atorvastatin has been shown to induce signifi cant increases in fibrinogen (22% increase; p < 0.05) by using the immunone phelometric method. This method also demonstrated that lovastatin use was a ssociated with a 24.4% increase (p < 0.0001) in plasma fibrinogen concentra tion. Simvastatin has been shown in multiple studies using the Clauss metho d to have a neutral effect on fibrinogen. The majority of studies have reve aled significant decreases (7-19%) in fibrinogen following treatment with p revastatin. CONCLUSIONS: Future studies need to be performed evaluating the effects of HMG-CoA reductase inhibitors on fibrinogen, but using direct comparisons an d clotting assay methodology.