High-sensitivity C-reactive protein elevation in patients with prior myocardial infarction in the United States

Importance: The extent to which levels of high-sensitivity C-reactive protein (hs-CRP), a known marker of increased cardiovascular risk, are elevated and are associated with standard cardiovascular risk factors in patients with a history of myocardial infarction (MI) is unknown.

Objectives: To determine the pattern and determinants of the distribution of hs-CRP in those with a prior MI in the United States using a nationally representative sample.

Design and participants: Adults with hs-CRP data in the National Health and Nutrition Examination Surveys from 1999-2010.

Results: Among 1296 individuals in our cohort, the median age was 65 years and the median hs-CRP level was 2.69 mg/L, measured an average of 7.1 years after the MI. Among these patients, 22% had hs-CRP levels of <1 mg/L, 61% had ≥2 mg/L, and 48% had ≥3 mg/L. Increasing hs-CRP was associated in a multivariable model with increasing body mass index (partial R² [pR²] 0.113, P < .001), increasing non-high-density lipoprotein [HDL] (pR² 0.030, P < .001), increasing age (pR² 0.008, P = .017), and decreasing HDL (pR² 0.005, P = .046). Adjusted mean hs-CRP was also higher in women (3.6 vs 2.7 mg/L; P < .001), in people with hypertension (3.5 vs. 2.8, P = .030), and among smokers (4.2 vs 2.3 mg/L; P < .001), and lower in people with hyperlipidemia (2.8 vs. 3.5, P = .007). Standard cardiovascular risk factors accounted for only 22% of the variability in hs-CRP levels.

Conclusions and relevance: Among patients with prior MI, elevated hs-CRP is prevalent several years after the MI, and standard cardiovascular risk factors explain only a small proportion of hs-CRP variability. In light of emerging evidence on the importance of inflammation in the pathogenesis of cardiovascular disease, the high prevalence of elevated hs-CRP in patients with prior MI in the United States may have public health implications.