Clinical Efficacy of an Automated High-Sensitivity C-Reactive Protein Assay

TLDR

C‑reactive protein predicts future cardiovascular events, but high‑sensitivity methods are needed for accurate risk assessment. The study compared the efficacy of a commercial latex‑enhanced hs‑CRP assay to a validated ELISA for predicting peripheral arterial disease. A prospective nested case‑control study measured baseline hs‑CRP in 144 men who later developed PAD and 144 matched controls over 60 months, comparing a latex assay to an ELISA, which showed a strong correlation (r = 0.95). Both assays identified higher hs‑CRP in PAD cases, with relative risk rising by 31 % per interquartile increase for ELISA and 34 % for Latex, demonstrating that the latex method is as effective as the ELISA for risk stratification.

Abstract

Prospective studies have shown that C-reactive protein (CRP) can be used to predict risk of future cardiovascular events. High-sensitivity methods for CRP (hs-CRP) measurement are needed for this purpose.We compared the clinical efficacy of an automated and commercially available latex-enhanced assay (Latex) for hs-CRP (Dade Behring) to a validated in-house ELISA, previously shown to predict future peripheral arterial disease (PAD) in asymptomatic populations. Using a prospective, nested, case-control design, we measured baseline hs-CRP concentrations in 144 apparently healthy men who subsequently developed symptomatic PAD and 144 age- and smoking habit-matched controls who remained free of vascular disease over the follow-up period of 60 months.The two hs-CRP assays correlated highly (r = 0.95; P <0.001), and all but two participants were classified into concordant quartiles or varied by only one quartile. The median hs-CRP of the case group was significantly higher than that of controls when measured by either the ELISA (1.34 vs 0.99 mg/L; P = 0.034) or the Latex method (1.80 vs 1.20 mg/L; P = 0.042). Furthermore, for both ELISA and the Latex method, the calculated relative risks of developing PAD increased significantly with each increasing quartile of hs-CRP. The calculated interquartile increase in relative risk of PAD was 31% (95% confidence interval, 5.2-62.2%; P = 0.01) for ELISA and 34% (95% confidence interval, 8.2-66.1%; P = 0.007) for the Latex method.Our findings indicate that the Latex method is equally as efficacious as the validated ELISA in classifying patients into cutoff points established by prospective studies for risk stratification for coronary and cerebrovascular disease.