Erythrocyte Sedimentation Rate More Sensitive to Change Than C-Reactive Protein in Rheumatoid Arthritis Patients

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Erythrocyte Sedimentation Rate More Sensitive to Change Than C-Reactive

Protein in Rheumatoid Arthritis Patients

05/20/2004

By Emma Hitt, PhD

The erythrocyte sedimentation rate (ESR) appears to be more sensitive to

change than is C-reactive protein (CRP) after 12 weeks and 24 weeks of

treatment with disease-modifying medications in rheumatoid arthritis (RA), a

new report suggests.

The ESR and CRP tests are the most widely used tests for measuring RA

disease activity; however, few studies have compared their evaluative

properties in patients with RA.

M. Ward, MD, with the National Institute of Arthritis and

Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda,

land, United States, searched the literature to identify clinical trials

and observational studies of disease-modifying medications and

corticosteroids in RA.

All 123 studies selected reported results for both ESR and CRP before

treatment and 4 weeks to 24 weeks after treatment in the same patients.

Effect sizes were evaluated by dividing the change in the test with

treatment by the pretreatment standard deviation. Within each study, a

pooled analysis was performed on the paired differences in effect sizes for

ESR and CRP.

Within the 123 studies, 184 active treatment arms that included measurements

of both ESR and CRP were identified. In addition, 63 studies with 90 active

treatment arms provided sufficient data to permit calculation of effect

sizes.

At 12 weeks, data from 36 treatment arms indicated that ESR was

significantly more sensitive to change than CRP, with a paired difference in

effect sizes of 0.09 units (P = .005). Likewise, in the 76 treatment arms

that reported results at 24 weeks, the ESR was also significantly more

sensitive to change, with a paired difference in effect sizes of 0.11 units

(P = .0004).

" A difference of similar magnitude, favoring the ESR, was also present at 16

weeks of treatment, " Dr. Ward notes.

According to the report, the sensitivity to change of the ESR was not

associated with its level at study entry, while the baseline concentration

of ESR was associated with its sensitivity to change at 12 weeks. In

contrast, the sensitivity to the change of the CRP was higher in studies

with higher baseline CRP concentrations, suggesting that the sensitivity to

change of the CRP is limited by ceiling effects more so than that of the

ESR.

J Rheumatol 2004;31:884-895