Overweight modifies the longitudinal association between uric acid and some components of the metabolic syndrome: The Tromso Study

Background: Elevated uric acid (UA) is associated with the presence of the metabolic syndrome (MetS). In a prospective cohort study, we assessed whether baseline and longitudinal change in UA were risk factors for development of MetS and its individual components. Methods: We included 3087 women and 2996 men who had UA measured in the population based Tromso Study 1994-95. The participants were stratified according to body mass index (BMI). Endpoints were MetS and each component of the syndrome after 7 years, according to the revised National Cholesterol Education Program's Adult Treatment Panel III (NCEP-ATP III) definition. Results: Multiple logistic regression analyses showed that higher baseline UA was associated with higher odds of developing elevated blood pressure in overweight subjects (BMI = 25 kg/m(2), odds ratio [OR] per 59 mu mol/L UA increase 1.44, 95 % confidence interval [CI] = 1.17-1.77, P = 0.001), but not in normal-weight subjects (BMI < 25 kg/m(2), P for interaction = 0.04). Overweight also modified the association between baseline UA and the development of elevated fasting glucose (P for interaction = 0.01). UA was a predictor of MetS in all subjects (OR per 59 mu mol/L UA increase 1.29, 95 % CI 1.18-1.41, P < 0.001). Furthermore, longitudinal UA change was independently associated with the development of MetS in all subjects (OR per 59 mu mol/L UA increase over 7 years 1.28, 95 % CI 1.16-1.42, P < 0.001). Conclusion: Increased levels of baseline UA independently predicted development of elevated blood pressure and higher fasting glycemia in the overweight, but not the normal-weight subjects. Baseline UA and longitudinal increase in UA over 7 years was associated with the development of MetS in all subjects. Whether increased UA should be treated differently in normal-weight and overweight persons needs further study.