Comparison of high-sensitivity C-reactive protein serum assay results obtained using Dade-Behring BNII nephelometer and Ortho Vitros FS 5.1 clinical analyzer in respect of CRP-related risk assessment of chronic metabolic diseases.

BACKGROUND

Serum concentration of high sensitive C-reactive protein (hsCRP) can predict the risk of chronic metabolic and cardiovascular diseases but it is unclear whether turbidimetric high sensitive assays of CRP are adequate.

METHODS

Concentrations of serum CRP in 126 samples of serum were measured with high-sensitivity methods using nephelometry (BN II Nephelometer) and turbidimetry (Ortho Vitros FS 5.1).

RESULTS

For CRP concentrations measured by nephelometry and turbidimetry intra-assay CVs were 3.2 and 0.9% at mean CRP concentrations of 1.4 and 2.1 mg/l, inter-assay CVs for commercial controls were 3.1% and 3.6% at mean concentrations of 1.3 and 1.7 mg/l, and mean biases were 7.62% and 2.26%, respectively. Measurements were strongly, linearly correlated (r = 0.99; CRP vitros = 0.03 +1.03 CRP (BN II)). When disease risk was assessed by nephelometry and turbidimetry, results were similar. If the risk of disease was classified as moderate (1.0 < CRP < or = 3.0 mg/l) or high (CRP > 3.0 mg/l), the frequency of misclassified cases was only 2.3 and 2.1%, respectively. The classification agreement weighted kappa coefficient was 0.94 (95% C.I.: 0.89-0.98).

CONCLUSIONS

turbidimetric high sensitive CRP assays can properly classify CRP-related prediction of chronic metabolic diseases with special consideration on cardiovascular risk.