Analytical performance and clinical efficacy for cardiovascular risk estimation of an Olympus immunoturbidimetric...

Increased C-reactive protein (CRP) concentration within the reference interval (<10.0 mg/L) is a strong predictor of cardiovascular disease (CVD) in apparently healthy adults. Cutoff points for use of CRP in estimating CVD risk are <1, 1-3 and >3 mg/L for low, average and high relative risk, respectively. For measuring CRP concentrations to assess cardiovascular risk, high-sensitivity CRP (hsCRP) assays have been developed. The aim of this study was to evaluate the analytical performance and clinical efficacy for cardiovascular risk estimation of the Olympus immunoturbidimetric latex CRP assay (sensitive application). The comparative method used was the CardioPhase* hsCRP assay, approved by the Food and Drug Administration for use in CVD risk assessment. The imprecision of the Olympus hsCRP assay in the concentration range 0.2-10.0 mg/L was 0.38-8.16% within runs and 3.75-9.63% between runs. For method comparison studies, 194 fresh serum samples were selected to cover the interval 0.15-10.0 mg/L CRP. Comparison of the Dade Behring and Olympus methods was performed using weighted Deming regression analysis (slope 0.99 mg/L, intercept 0.002 mg/L, S(y,x)=0.02 mg/L, r=0.992) and a Bland-Altman relative difference plot (mean difference -0.002%, SD=0.040%). The agreement between the Dade Behring and Olympus methods for relative risk class assignments was 95.4%. Statistical analysis of the agreement between the two methods for each relative risk class showed that the differences between the methods were not statistically significant (p>0.10). Although previous reports found poor performance of the Olympus CRP tests for use in cardiovascular and peripheral vascular risk estimation, our study proved good analytical performance and clinical efficacy of the Olympus hsCRP assay for this use.