Analytical performance and agreement between different laboratory technologies for hs-CRP Measurements

High-sensitivity CRP (hsCRP) is a validated biomarker of low-grade vascular inflammation that refines risk stratification, particularly in primary prevention when the decision to initiate statin therapy is otherwise uncertain for cardiovascular risk comparable in magnitude to blood pressure or LDL cholesterol. In the Physicians' Health Study and more than 50 subsequent epidemiologic studies, elevated hsCRP predicted first-ever vascular events years in advance in healthy subjects, and a 2010 meta-analysis of >160,000 subjects found each SD increase in log-hsCRP conferred a relative risk of 1.37 for coronary heart disease and 1.55 for cardiovascular mortality effect sizes comparable to total cholesterol, HDL-C, and blood pressure. [Ridkler 2016] hsCRP assays use enhanced immunoassay methods most commonly particle-enhanced immunoturbidimetric or immunonephelometric assays that extend the analytic range down to 0.15–0.3 mg/L, well below the detection limit of standard CRP assays used for acute infection/inflammation. Immunoturbidimetric assays (e.g., Beckman Coulter AU5800, Roche Cobas systems) CRP–antibody aggregation produces turbidity measured photometrically with light scattering proportional to CRP concentration.

Immunonephelometric assays (e.g., Behring Nephelometer or NHANES) similarly quantify antigen-antibody complex formation but measure scattered rather than transmitted light.
Method comparison was performed using 52 human serum samples. Samples were analyzed on the Atellica system (Siemens) at the Maccabi Healthcare Services North Mega Laboratory (Yokneam) at 571 nm and compared with results obtained using the Beckman AU680 analyzer, based on a turbidimetric assay at 570 nm, at Ziv Medical Center (Safed). Detection ranges vary by platform. For the Siemens Atellica hsCRP assay, the measuring interval is 0.16–9.5 mg/dL, with a limit of detection (LoD) of 0.11 mg/L and a limit of quantification (LoQ) of 0.16 mg/L. Beckman technology measuring range is 0.8-8 mg/L with LOD= 0.08 mg/L.