BACKGROUND: High-sensitivity c-reactive protein (hs-CRP) is an established risk predictor in primary prevention. Among available laboratory methods, enzyme linked immunosorbent assay (ELISA) and nephelometry are the most validated for this clinical application. Immunoluminometry is another high-sensitivity method of hs-CRP, with definitive prognostic value in acute coronary syndromes. However, it lacks validation for cardiovascular risk prediction in the outpatient setting, whose hs-CRP values are in a lower range in relation to unstable patients. OBJECTIVE: In an outpatient setting, test the hypothesis that the immunoluminometric method has enough accuracy to measure hs-CRP and classify individuals according to cardiovascular risk. METHOD: C-reactive protein was measured by the methods of immunoluminometry and nephelometry in 152 serum samples obtained from different outpatient subjects. Taken nephelometry as a gold-standard, performance of the immunoluminometric method was evaluated. RESULTS: There was a strong linear association between the two methods, according to the correlation coefficient (r = 0.996; p < 0.001) and regression coefficient (beta = 0.94, 95% C.I. = 0.92-0.95, p < 0.001). The mean difference between the two methods was - 0.22 ± 0.4mg/l. In 97% of the subjects, there was agreement between the methods in definition of low risk (hs-CRP < 1mg/l), intermediate risk (hs-CRP = 1-3mg/l) or high cardiovascular risk (hs-CRP > 3mg/l) - kappa = 0.96; p < 0.001. CONCLUSION: The immunoluminometric method of hs-CRP represents an alternative to nephelometry for the assessment of cardiovascular risk in an outpatient population.
C-reactive protein; Cardiovascular risk; Immunoluminometry; Nephelomerty
