Rheumatoid arthritis in the Pima Indians of Arizona: an assessment of the clinical components of the New York criteria.

When a prevalence study of Rheumatoid Arthritis (RA) was made in the adult Pima Indian population living on the Gila River Reservation, a high prevalence was found using the New York criteria (5-9 per cent). This was mainly due to the high frequency of limitation of motion which brought in many undesirable subjects. After excluding it as a component of New York criteria we found a prevalence for RA of 3 per cent with a predominance among the females (3-8 as against 2-0 per cent in males). The group so defined fulfilled the requirements of the Rome criteria, showed a higher concordance with serological or radiological evidence of RA, and appeared to identify subjects in whom the experienced clinical rheumatologist would more often agree with the diagnosis.