C-Reactive Protein Concentrations Are Very High and More Stable over Time Than the Traditional Vascular Risk Factors Total Cholesterol and Systolic Blood Pressure in an Australian Aboriginal Cohort

BACKGROUND: Stability of circulating high-sensitivity C-reactive protein (hsCRP) concentrations has implications for its utility in assessing cardiovascular disease (CVD) risk. We sought to determine hsCRP reproducibility in an indigenous Australian cohort with a view to use hsCRP as a marker of future CVD in community-based risk-factor screenings. METHODS: Seventy people living in a community on the northern coast of Australia participated in 2 risk-factor screenings over a median (interquartile range) follow-up time of 829 (814-1001) days. hsCRP was measured by high-sensitivity nephelometry. RESULTS: Geometric mean hsCRP concentrations at baseline and follow-up were 4.5 and 5.1 mg/L, respectively (P = 0.220), and Pearson product-moment correlation was 0.775. The proportion of people at high CVD risk (hsCRP >3.0 mg/L) at baseline was 67.1% and remained consistently high (68.6%) at follow-up Linear regression analysis for follow-up hsCRP as a function of baseline hsCRP, sex, and differences in total and regional body fatness showed that baseline hsCRP was the single predictor in the model, accounting for 63.9% of the total variance in follow-up hsCRP (P-model < 0.001). Prevalence agreement (95% Cl) between baseline and follow-up for the hsCRP >3.0 mg/L category was 84% (73%-92%) (P-McNemar = not significant), and kappa coefficient was fair (0.64, compared with 0.31 for systotic blood pressure >= 140 mmHg and 0.43 for total cholesterol; >= 5.5 mmol/L. CONCLUSIONS: hsCRP concentrations remained consistently reproducible over time across a wide concentration range in an Aboriginal cohort. Correlations between concentrations over time were better than for other traditional CVD risk factors. hsCRP concentration has potential as a marker of future CVD risk. (C) 2008 American Association for Clinical Chemistry