HMG-CoA reductase inhibitors, other lipid-lowering medication, antiplatelet therapy, and the risk of venous thrombosis

BACKGROUND: Statins [3-hydroxymethyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors] and antiplatelet therapy reduce the risk of atherosclerotic disease. Besides a reduction of lipid levels, statins might also have antithrombotic and anti-inflammatory properties, and anti-platelet therapy reduces clot formation. We have studied the risk of venous thrombosis with use of statins, other lipid-lowering medication, and antiplatelet therapy.

MATERIALS AND METHODS: Patients with a first episode of deep vein thrombosis in the leg or pulmonary embolism between March 1999 and September 2004 were included in a large population-based case-control study (MEGA study). Control subjects were partners of patients (53%) or recruited via a random-digit-dialing method (47%). Participants reported different all-medication use in a questionnaire.

RESULTS: Of 4538 patients, 154 used statins (3.3%), as did 354 of 5914 control subjects (5.7%). The use of statins [odds ratio (OR) 0.45; 95% confidence interval (CI) 0.36-0.56] but not other lipid-lowering medications (OR 1.22; 95% CI 0.62-2.43), was associated with a reduced venous thrombosis risk as compared with individuals who did not use any lipid-lowering medication, after adjustment for age, sex, body mass index, atherosclerotic disease, antiplatelet therapy and use of vitamin K antagonists. Different types and various durations of statin therapy were all associated with a decreased venous thrombosis risk. Antiplatelet therapy also reduced venous thrombosis risk (OR 0.56; 95% CI 0.42-0.74). However, sensitivity analyses suggested that this effect is most likely explained by a so-called 'healthy user effect'. Simultaneous use of medication most strongly reduced venous thrombosis risk.

CONCLUSION: These results suggest that the use of various types of statins is associated with a reduced risk of venous thrombosis, whereas antiplatelet therapy and other lipid-lowering medications are not.