C-reactive protein in the assessment of disease activity in juvenile rheumatoid arthritis and juvenile spondyloarthritis.

Disease activity in 31 children with JRA and 12 with JSA was investigated clinically and by serial measurements of serum CRP and ESR over a one-year period. Prior mean duration of disease was 4.3 years. There was a significant correlation of CRP with ESR and both parameters correlated significantly with clinical disease activity. CRP concentrations and ESR in active disease were significantly higher than in moderately active and inactive disease, though neither parameter showed any significant difference between moderately active and inactive disease. Clinical scoring was more sensitive in detection of moderate disease activity than were CRP and ESR. However, in systemic JRA without articular involvement, laboratory parameters were more useful for assessing disease activity.