The performance of the 1987 ARA classification criteria for rheumatoid arthritis in a population based cohort of patients with early inflammatory polyarthritis

Objective. The 1987 American Rheumatism Association (ARA) criteria for rheu matoid arthritis (RA) were developed to discriminate between patients with established RA and those with another rheumatological disorder. Their abili ty to determine which patients presenting with early synovitis have "true" RA is not known. We evaluated whether the 1987 ARA classification criteria for RA in patients newly presenting with inflammatory polyarthritis (IP) pr edict persistent, disabling, or erosive arthritis. Methods. We studied 486 patients with early IP referred to the Norfolk Arth ritis Register. The 1987 ARA criteria were applied at baseline, and assesse d for their ability to identify (1) patients referred to hospital for whom the diagnosis of RA was recorded by the hospital physician; (2) patients at 3 years with (a) persistent synovitis; (b) moderate or greater disability; and (c) erosions. Results, At baseline, 323 (67%) patients satisfied the ARA criteria in the classification tree format. Exactly 50% of those referred to hospital were given a diagnosis of RA. By 3 years, 76% of the 486 patients had persistent disease, 36% had a Health Assessment Questionnaire score greater than or e qual to 1, and 40% had erosions. The sensitivity of the criteria was good, ranging from 77 to 87% depending on the outcome. The specificities were poo r, and thus the overall discriminatory ability showed little improvement ov er random probability. Conclusion. Among patients newly presenting with IF, the 1987 ARA criteria for RA had a low ability to discriminate between patients who developed per sistent, disabling, or erosive disease and those who did not. Alternative c riteria are required for studies investigating early RA.