title: Intra-individual variability of high-sensitivity C-reactive protein in Chinese general population.
abstract: 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.
authors.affiliation: Department of Cardiology, Kailuan Hospital, Tangshan, China. wushouling@gmail.com
authors.forename: Shouling
authors.initials: S
authors.lastname: Wu
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.forename: Cheng
authors.initials: C
authors.lastname: Jin
authors.forename: Peng
authors.initials: P
authors.lastname: Yang
authors.forename: Dongqing
authors.initials: D
authors.lastname: Li
authors.forename: Hongfeng
authors.initials: H
authors.lastname: Li
authors.forename: Chong
authors.initials: C
authors.lastname: Shen
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000208:ethnology* / Q000235:genetics; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000097:blood* / Q000208:ethnology* / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D014644:Genetic Variation / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein