Levels of C-reactive protein associated with high and very high cardiovascular risk are prevalent in patients with rheumatoid arthritis

Abstract

Objective: C-reactive protein (CRP) levels>3 mg/L and>10 mg/L are associated with high and very high cardiovascular risk, respectively, in the general population. Because rheumatoid arthritis (RA) confers excess cardiovascular mortality, we determined the prevalence of these CRP levels among RA patients stratified on the basis of their RA disease activity.

Methods: We evaluated physician and patient global assessments of disease activity, tender and swollen 28 joint counts, erythrocyte sedimentation rate (ESR), and CRP measured in a single clinic visit for 151 RA patients. Disease activity was calculated using the Clinical Disease Activity Index (CDAI) and the Disease Activity Score 28 Joints (DAS28-ESR and DAS28-CRP).

Results: Median CRP level was 5.3 mg/L. 68% of patients had CRP>3 mg/L, and 25% had CRP>10 mg/L. Of those with 0-1 swollen joints (n = 56), or 0-1 tender joints (n = 81), 64% and 67%, respectively, had CRP>3 mg/L, and 23% and 20%, respectively, had CRP>10 mg/L. Of those with remission or mildly active disease by CDAI (n = 58), DAS28-ESR (n = 39), or DAS28-CRP (n = 70), 49-66% had CRP>3 mg/L, and 10-14% had CRP>10 mg/L. Of patients with moderate disease activity by CDAI (n = 51), DAS28-ESR (n = 78), or DAS28-CRP (n = 66), 67-73% had CRP>3 mg/L, and 25-33% had CRP>10 mg/L.

Conclusion: Even among RA patients whose disease is judged to be controlled by joint counts or standardized disease scores, a substantial proportion have CRP levels that are associated high or very high risk for future cardiovascular events in the general population.

Figure 1. Scatterplots of CRP Levels by (a) Physician and (b) Patient Global Assessments of Disease Activity.

CRP (log2) levels and global assessments were determined at the same clinic visit. The global assessments were recorded independently using a 100 mm visual analog scale in which 0 = no disease activity and 100 = maximal disease activity. The dotted reference lines denote a global assessment of 30 and CRP = 3 mg/L. CRP levels>3 mg/L are associated with high cardiovascular risk in the general population according to a scientific statement from the AHA and the CDC (7).

Figure 2. CRP Levels by (a) Swollen and (b) Tender Joint Count Category.

CRP (log2) values are shown within each swollen joint count category. CRP levels and joint counts were determined at the same clinic visit. Blue lines denote location of the median. The dotted reference line is at CRP = 3 mg/L.

Figure 3. CRP Levels by Disease Activity as Determined by CDAI.

CRP (log2) values are shown within each CDAI category. CRP levels and CDAI were determined at the same clinic visit. Blue lines denote location of median. The dotted reference line is at CRP = 3 mg/L.

Figure 4. CRP Levels by Disease Activity as determined by (a) DAS28-ESR and (b) DAS28-CRP.

CRP (log2) values are shown within each swollen joint count category. CRP levels and DAS28 were determined at the same clinic visit. Blue lines denote location of median. Dotted reference line is at CRP = 3 mg/L.