Clinical research study
C-Reactive Protein, Inflammatory Conditions, and Cardiovascular Disease Risk

https://doi.org/10.1016/j.amjmed.2007.08.037Get rights and content

Abstract

Background

It is uncertain to what extent high C-reactive protein (CRP) concentrations reflect the presence of inflammatory conditions in the community.

Methods

We evaluated 3782 Framingham Offspring Study participants (mean age 55 years; 52% women) free of baseline cardiovascular disease. Logistic regression models examined the prevalence of common inflammatory conditions by CRP categories, while a separate matched case-referent analysis evaluated the prevalence of uncommon inflammatory conditions. Cox models were used to assess the influence of common inflammatory conditions on relations between CRP and incident cardiovascular disease.

Results

Common inflammatory conditions were reported by nearly half of the participants; these individuals were more likely to have markedly high CRP concentrations (>10 mg/L, P for trend = .001). In multivariable models, there were increased odds of having at least one common inflammatory condition with CRP concentrations of 1-3.0, 3.01-10, and >10 mg/L, compared with the referent category (<1 mg/L); the respective odds ratios with 95% confidence intervals were 1.41 (1.07-1.86), 1.45 (1.07-1.98), and 1.64 (1.09-2.47) in men, and 1.08 (0.82-1.43), 1.07 (0.80-1.44), and 1.38 (0.97-1.96) in women. In case-referent analyses, uncommon inflammatory conditions were more common in individuals with CRP >10 mg/L compared with those with CRP <1 mg/L (12.1% vs 6.6%; P = .0001). In multivariable models, higher CRP categories were not associated with incident cardiovascular disease, and with additional adjustment for inflammatory conditions, results remained unchanged.

Conclusion

There is high prevalence of common and uncommon inflammatory conditions in individuals with high CRP concentrations. Higher CRP concentrations should be interpreted with caution in cardiovascular disease risk assessment.

Section snippets

Study Sample

The design and selection criteria for Framingham Offspring Study have been described previously.26 For primary analyses, we selected all participants who attended the fifth examination cycle (1991-1995) and had CRP concentrations measured (n = 3782; 1973 women). We excluded participants with prevalent cardiovascular disease at baseline (n = 365), resulting in an available sample of 3417 (1842 women) participants. This sample was used to assess the prevalence of common inflammatory conditions (as

Results

Mean age of the participants was 55 ± 10 years (52% women; Table 1). Participants with prevalent inflammatory conditions were more likely to report current cigarette smoking. Blood pressure, total/HDL cholesterol ratio, and prevalence of diabetes were slightly higher among men compared with women.

Discussion

In our sample of middle-aged to elderly men and women, markedly high CRP concentrations (>10 mg/L) were not uncommon (9.4% of men and 14.0% women). At least one chronic inflammatory condition was reported by nearly half of men and women who were free of prevalent cardiovascular disease. The prevalence of common inflammatory conditions increased with increasing concentrations of CRP. Conversely, participants with low CRP concentrations (<1 mg/L) were less likely to report a common chronic

Conclusion

In our community-based sample, elevated and, in particular, markedly high concentrations of CRP (>10 mg/L) are associated with a significantly higher prevalence of common, as well as uncommon, inflammatory conditions. Further research is warranted using comprehensive, validated ascertainment of inflammatory conditions and high-sensitivity CRP assays to assess the impact of common inflammatory conditions on cardiovascular disease risk prediction. Our findings reinforce previous statements that

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    Supported by the NHLBI’s Framingham Heart Study contract NHLBI N01 HC 25195; R01 HL 073272 01, R01 HL 64753, and R01 HL 076784; and the Donald W. Reynolds Foundation Program in Clinical Cardiovascular Research.

    Part of this article was presented as a poster at the American Heart Association annual scientific sessions, New Orleans, Louisiana, on November 9, 2004.

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