The ability of the wide range CRP assay to classify individuals with low grade inflammation into cardiovascular risk groups

Background High sensitivity C-reactive protein (hsCRP) has become a routine assessment tool to discriminate between patients at low, intermediate or high risk for cardiovascular events using the threshold values of 1 and 3 mg/L, respectively. Over the past years, several studies have proposed the wide range C-reactive protein (wrCRP) as an alternative to the hsCRP in various clinical scenarios. However, the potential use of wrCRP in assessing the cardiovascular risk has not yet been evaluated. Methods Both wrCRP and hsCRP were evaluated in 15,780 apparently healthy individuals who underwent a routine annual checkup in the Tel Aviv Sourasky Medical Center. Individuals with CRP levels > 5 mg/L were excluded. Agreement between the two methods was observed using the Bland-Altman method and the concordance correlation coefficient. Deming regression was used to build a calibration equation. Reclassification of individuals’ risk level was observed and Cohen's kappa was used to evaluate risk agreement. Results A high correlation (r = 0.98) along with a significant difference (p < 0.001) between hsCRP and wrCRP raised the need for calibration. A simple calibration equation (Adjusted wrCRP = 0.3136 + 0.8803 × wrCRP) led to high agreement which enabled 8.4% reclassification of the risk group. A change in the intermediate risk threshold value from 1 to 0.9 mg/L led to an almost perfect agreement (kappa = 0.87, p < 0.001) and a low reclassification rate (7.6%), with under 0.05% of the population undergoing a major reclassification (from high to low risk or vice versa). Conclusions In the era of limited financial resources, wrCRP assay may be used as a reasonable routine assay to evaluate the cardiovascular risk in patients undergoing a routine annual checkup.