Impact of High-Sensitivity C-Reactive Protein Cutoff Selection on Cardiovascular Risk Classification Beyond Lipid Measurements in Korean Adults: A KNHANES 2024 Study

Background/Objectives: This study aimed to describe the distribution of high-sensitivity C-reactive protein (hsCRP) in Korean adults and to evaluate the incremental detection of elevated hsCRP beyond lipid abnormalities using nationally representative data. Methods: We analyzed 2024 Korean National Health and Nutrition Examination Survey data from adults aged ≥20 years with available hsCRP and lipid measurements, excluding pregnant women. Elevated hsCRP was defined using three cutoffs: ≥1 mg/L, ≥2 mg/L, and >3 mg/L. Additional detection by hsCRP was defined as the proportion of participants without any lipid abnormality, as defined according to the NCEP ATP III criteria, who had elevated hsCRP. Results: A total of 5769 adults were included in the common hsCRP and lipid analysis population. In the survey-weighted analysis, 72.5% of participants had hsCRP < 1 mg/L, whereas 12.8%, 6.2%, 6.9%, and 1.6% had hsCRP 1 to 3 to 3 mg/L were 27.5%, 14.7%, and 8.5%, respectively. Any lipid abnormality was present in 34.4% of participants. Among 3861 participants with normal lipid profiles, elevated hsCRP was found in 22.6%, 11.7%, and 6.8%, corresponding to overall additional detection rates of 14.8%, 7.7%, and 4.4% at cutoffs of ≥1, ≥2, and >3 mg/L, respectively. Conclusions: hsCRP identified additional individuals who were not detected by conventional lipid abnormalities. These findings provide nationally representative descriptive data on hsCRP distribution and threshold-based classification in Korean adults and underscore the need for population-specific interpretation of hsCRP cutoffs.