Abstract 3488: Hyperuricemia and the Risk of Isolated Hypertension among Young People without Cardiovascular and Metabolic Risk Factors: The CARDIA Study

Abstract

PURPOSE: The association between higher serum uric acid (SUA) levels and hypertension in the context of the metabolic syndrome is well known. If such an association was causal, one would expect to demonstrate a link between hyperuricemia and incidence of isolated hypertension - a hypothesis that has not been tested so far. METHODS: We used the 15-year limited-access data from the prospective cohort study of Coronary Artery Risk Development in young adults (CARDIA), sponsored by the National Institutes of Health, to identify a group of non-smoking young people with normal blood pressure and free of insulin resistance, hyperlipidemia, obesity, and a family history of cardiovascular diseases. These young people aged between 18 and 30 years at baseline were followed-up for a period of 15 years by 6 study visits where all cardiovascular risk factors were reassessed. Incidence of JNC-7 hypertension was the outcome of interest in Cox proportional hazards models where age, gender, race, lipid levels, blood pressure, alcohol, body mass index, smoking and serum insulin levels (time-varying where appropriate) were the covariates. Baseline serum uric acid (continuous) was the independent variable of interest. A second set of Cox regression analyses was performed among the subgroup of these individuals who remained free of all cardiovascular risk factors (except for hypertension) over the 15-year follow up. RESULTS: Out of the 5113 CARDIA participants at baseline, 2057 subjects were free of cardiovascular risk factors at baseline and were available for evaluation at year 15. Over the follow-up period, 828 subjects developed hypertension. In multivariate Cox models, each mg/dl increase in serum uric acid was associated with a hazard ratio of 1.45 (1.09–1.91). In the second set of analyses, 753 were free of all cardiovascular risk factors at baseline and remained free of any of the components of the metabolic syndrome except hypertension (n = 122 incident cases of hypertension) were studied. In these analyses each mg/dl increasse in SUA was associated with a risk adjusted hazard ratio of 1.60 (95% CI 1.02–2.49). CONCLUSIONS: Unrelated to the other features of the metabolic syndrome, higher levels of SUA among young people predicts isolated hypertension.