C-Reactive Protein versus Erythrocyte Sedimentation Rate: Implications Among Patients with No Known Inflammatory Conditions

Abstract

Background: Measurements of C-reactive protein (CRP) concentration and erythrocyte sedimentation rate (ESR) are frequently ordered jointly in clinical practice.

Aim: To investigate the factors associated with discordances between CRP concentration and ESR in adults.

Methods: We conducted a cross-sectional study of 1472 adults with no known inflammatory disorders (44.5% male; median age, 52 years; range, 18-91 years), randomly selected from a municipality in Spain. The participants underwent simultaneous measurements of ESR, serum CRP, and interleukin-6 concentrations. Alcohol consumption, smoking, and physical activity were evaluated by questionnaire. Body mass index (BMI) measurement and metabolic syndrome criteria were available for all participants.

Results: Most (n = 1123, 74.9%) of the participants showed normal CRP and ESR values. Sixty-nine (4.6%) participants showed high CRP and ESR values. Seventy-two (4.8%) participants showed a discordant pattern of high ESR and normal CRP values, which was associated with age after adjusting for sex, alcohol consumption, physical activity, BMI, and the presence of metabolic syndrome (odds ratio [OR], 1.052; 95% CI, 1.034-1.071; P < .001). A total of 208 (13.8%) participants showed a discordant pattern of high CRP and normal ESR values, which was associated with BMI after adjusting for covariates (OR, 1.099; 95% CI, 1.064-1.136; P < .001). BMI appeared to be the main determinant of serum CRP concentrations in this population. Serum interleukin-6 concentrations were positively associated with the discordant pattern of high CRP and normal ESR values.

Conclusion: In this general adult population with no overt inflammatory disease, the discordant pattern of high ESR and normal CRP was associated with greater age, whereas the pattern of high CRP and normal ESR was associated with higher BMI.