Relationship between Inflammatory Cytokines and Uric Acid Levels with Adverse Cardiovascular Outcomes in Patients with Stable Coronary Heart Disease

BACKGROUND: So far it is unclear whether the association between serum uric acid (SUA), inflammatory cytokines and risk of atherosclerosis is causal or an epiphenomenon. The aim of the project is to investigate the independent prognostic relationship of inflammatory markers and SUA levels with adverse cardiovascular outcomes in a patient population with stable coronary heart disease (CHD). METHODS: SUA, C-reactive protein (CRP) and interleukin (IL)-6 were measured at baseline in a cohort of 1,056 patients aged 30–70 years with CHD. Cox proportional hazards model was used to determine the prognostic value of these markers on a combined CVD endpoint during eight year follow-up after adjustment for covariates. RESULTS: For 1,056 patients with stable coronary heart disease aged 30–70 years (mean age 58.9 years, SD 8.0) follow-up information and serum measurements were complete and n = 151 patients (incidence 21.1 per 1000 patients years) experienced a fatal or non-fatal CVD event during follow-up (p-value = 0.05 for quartiles of SUA, p = 0.002 for quartiles of CRP, p = 0.13 for quartiles of IL-6 in Kaplan-Meier analysis). After adjustment for age, gender and hospital site the hazard ratio (HR) for SUA increased from 1.37 to 1.65 and 2.27 in the second, third, and top quartile, when compared to the bottom one (p for trend <0.0005). The HR for CRP increased from 0.85 to 0.98 and 1.64 in the respective quartiles (p for trend 0.02). After further adjustment for covariates SUA still showed a clear statistically significant relationship with the outcome (p for trend 0.045), whereas CRP did not (p for trend 0.10). CONCLUSION: The data suggest that compared to inflammatory markers such as CRP and IL-6 serum uric acid levels may predict future CVD risk in patients with stable CHD with a risk increase even at levels considered normal.