Arterial cardiovascular risk factors and venous thrombosis: results from a population-based, prospective study (the HUNT 2)

Background An explanation for the increased risk of myocardial infarction and stroke in patients with venous thrombosis is lacking. The objective of this study was to investigate whether risk factors for arterial cardiovascular disease also increase the risk of venous thrombosis. Design and Methods Cases who had a first venous thrombosis (n=515) and matched controls (n=1,505) were identified from a population-based, nested, case-cohort study (the HUNT 2 study) comprising 71% (n=66,140) of the adult residents of Nord-Trondelag County in Norway. Results The age- and sex-adjusted odds ratio of venous thrombosis for subjects with concentrations of C-reactive protein in the highest quintile was 1.6 (95% confidence interval: 1.2-2.2) compared to subjects with C-reactive protein in the lowest quintile. This association was strongest in subjects who experienced venous thrombosis within a year after blood sampling with a three-fold increased risk of participants in the highest versus the lowest quintile. Having first degree relatives who had a myocardial infarction before the age of 60 years was positively associated with venous thrombosis compared to not having a positive family history [odds ratio 1.3 (95% confidence interval: 1.1-1.6)]. Subjects with blood pressure in the highest quintile had half the risk of developing venous thrombosis compared to subjects whose blood pressure was in the lowest quintile. There were no associations between the risk of venous thrombosis and total cholesterol, low density lipoprotein-cholesterol, high density lipoprotein-cholesterol, triglycerides, glucose or smoking. We confirmed the positive association between obesity and venous thrombosis. Conclusions C-reactive protein and a family history of myocardial infarction were positively associated with subsequent venous thrombosis. Blood pressure was inversely correlated to venous thrombosis. These findings should be confirmed by further investigations.