To examine serum concentrations of hyaluronic acid (HA) in patients with rheumatoid arthritis (RA) and to investigate the relationship between clinical measures of disease activity and serum HA concentrations in these patients.
Sixty-five patients with established RA were enrolled and RA disease activity was measured by clinical variables. Serum samples obtained at the time of the clinical evaluation were assayed for serum HA, erythrocyte sedimentation rate (ESR), and C reactive protein (CRP), and correlations between these laboratory variables and clinical disease activity were sought.
Concentrations of serum HA were higher in patients with RA than in healthy controls. There was statistically significant correlation between patient age and serum HA and between serum HA and disease activity measured by physician assessment and number of swollen joints. Correction for age strengthened the correlation between serum HA and measures of disease activity. ESR did not correlate with any measure of clinical disease activity. CRP concentrations correlated with physician assessment of disease activity, and number of swollen joints and tender joints, but the correlation was not as strong as the correlation between serum HA and disease activity variables.
Measurement of serum HA may be a useful measure of disease activity in patients with RA. Measurement of serum HA appears to be a better correlate of clinical disease activity in patients with RA than ESR or CRP.