Distribution of C‐Reactive Protein and Its Relation to Risk Factors and Coronary Heart Disease Risk Estimation in the National Health and Nutrition Examination Survey (NHANES) III

Abstract

The authors examined the distribution of, and risk factors associated with, the inflammatory marker C‐reactive protein (CRP) among a large sample of non‐institutionalized American adults aged 30–74 years of age, and its relation to estimated 10‐year coronary heart disease risk. The population studied comprised 4472 men and 5212 women aged 30–74 years, without coronary heart disease, who had CRP measurements in the Third National Health and Nutrition Examination Survey (NHANES III). The 10‐year risk of coronary heart disease was estimated from Framingham risk factor algorithms among those with CRP levels of ≤ 0.21 mg/dL, >0.21–<0.5mg/dL, 0.5–<1.0 mg/dL, and ≥1.0 mg/dL. Mean (SD) levels of CRP were 0.41 (0.64) mg/dL in men and 0.55 (0.91) mg/dL in women. Levels of at least 1 mg/dL were measured in 6.4% of men and 12.9% of women. CRP levels were highest among non‐Hispanic black men and Mexican‐American women. According to multiple logistic regression analysis, cigarette smoking and increased age, body mass index, and systolic blood pressure in men, and body mass index and diabetes in women, were strongly associated with a greater likelihood of CRP levels of ≥1.0 mg/dL (p<0.001). Among persons with CRP levels of ≥0.21 mg/dL, >0.21‐<0.5 mg/dL, 0.5‐<1.0 mg/dL and ≥1.0 mg/dL, the 10‐year estimated risk of coronary heart disease were 13.4%, 17.6%, 19.6%, and 21.1% among men, respectively, and 2.7%, 3.6%, 4.1% and 4.3% among women, respectively (both p<0.001 across CRP categories); higher risks across CRP groups were also found among ethnic/gender subgroups. CRP remained a significant predictor of coronary heart disease risk in unadjusted and age‐adjusted analyses. Conclusion. Elevation of CRP is associated with several major coronary heart disease risk factors and with unadjusted and age‐adjusted projections of 10‐year coronary heart disease risk in both men and women.