The value of the ACR 1987 criteria in very early rheumatoid arthritis.

We assessed the sensitivity and specificity of the ACR 1987 revised criteria for rheumatoid arthritis (RA) in 121 patients with recent-onset (< or = 6 months) RA, 68 with reactive arthritis (ReA), 19 with ankylosing spondylitis (AS), and 13 with psoriatic arthritis (PsA). The sensitivity of each single criterion ranged 8.3-90.9% and specificity 52.0-100%. The sensitivity of four fulfilled criteria was 83.5% and specificity 86.0%. In ReA 11.8%, AS 5.3%, and PsA 38.5% of patients fulfilled four criteria respectively. Thus at the beginning of RA, 83% of patients could be diagnosed correctly by using the ACR 1987 criteria, and the remaining 17% had seropositive and/or erosive arthritis at the onset. The suitability of the radiographic ACR criteria is discussed.