Intra-individual variability of high-sensitivity C-reactive protein in Chinese general population.

BACKGROUND: Intra-individual variability of high-sensitivity C-reactive protein (hsCRP) has implications for its utility in assessing the risk of cardiovascular disease. However, to our knowledge, none of the community-based studies have evaluated the variability of hsCRP in Chinese adults.
METHODS: 56,218 employees of Tangshan Kailuan Company, aged 18-96years participated in 2 health examinations over a two-year follow-up time. hsCRP was measured by high-sensitivity nephelometry. Intra-class correlation coefficient (ICC) and k statistic were used to evaluate the stability for quantitative variable and categorical variables respectively.
RESULTS: Geometric mean of hsCRP concentrations at baseline and follow-up were 0.95mg/L vs 1.67mg/L for male (P<0.05) and 0.98mg/L vs 1.66mg/L for female (P<0.05), respectively. Pearson correlation coefficient for hsCRP between baseline and follow-up were 0.37 and 0.44 for male and female, respectively (all P<0.05). The ICC of hsCRP (0.55 for male and 0.60 for female) was less than those for body mass index, systolic blood pressure, diastolic blood pressure, total cholesterol and fasting blood glucose in male and female. However, the k statistic (0.47 for male and 0.50 for female) of hsCRP (≥3mg/L) is greater than or near to those of systolic blood pressure, diastolic blood pressure, total cholesterol and fasting blood glucose. As the age increases, the stability of hsCRP in men and women gradually increased.
CONCLUSIONS: As a categorical variable (≥3.0mg/L), hsCRP has potential as a marker of future cardiovascular disease risk. However, the influence of age and gender should be taken into account in its application to the prediction of cardiovascular disease risk.