High sensitivity C-reactive protein as a disease activity marker in rheumatoid arthritis

To elucidate the potential contribution of high sensitivity C-reactive protein (hs-CRP) testing in the assessment of disease activity in rheumatoid arthritis (RA).

We recorded clinical and psychological variables, the hs-CRP, and erythrocyte sedimentation rate (ESR) in 146 consecutive patients with RA. We analyzed the associations between the ESR and hs-CRP versus the other recorded variables.

The median (interquartile range) ESR (mm/h) and hs-CRP (mg/l) were 15 (7-36) and 5 (2.3-13.9), respectively. Thirty-two (22%) patients had an hs-CRP < 2 mg/l, 61 (42%) an hs-CRP of 2-8 mg/l and 53 (36%) an hs-CRP > 8 mg/l. In patients with an hs-CRP of 2-8 mg/l, the swollen joint counts and the physician disease activity scales were higher, and remission rates were lower than in patients with an hs-CRP of < 2 mg/l. The hs-CRP was consistently more closely associated with disease activity, depression, and helplessness than was the ESR.

High sensitivity CRP testing reveals systemic inflammation that is generally not detectable with routine CRP assays and that is associated with disease activity in RA.