RHEUMATOID-ARTHRITIS IN THE PIMA-INDIANS - THE INTERSECTION OF EPIDEMIOLOGIC, DEMOGRAPHIC, AND GENEALOGIC DATA

Objective. To describe the clinical features and familial distribution of rheumatoid arthritis (RA) in the Pima Indians. Methods. From 1965 through 1990, all cases of RA as defined by the American College of Rh eumatology (formerly, the American Rheumatism Association) 1987 criter ia or all eases of seropositive, erosive disease as defined by the Rom e criteria were identified in individuals who were age 20 years and ol der and were of 50% or more Pima/Tohouo-O'odham heritage. Radiographs were reviewed by 2 musculoskeletal radiologists who were blinded to ca se status. Kinship coefficients were used to evaluate familial aggrega tion. Results. Eighty-eight RA cases were identified from this populat ion-based sample. Over 66% of the cases had seropositive disease, over 60% had erosive disease, and over 40% had subcutaneous nodules. Of th e 88 RA cases, 40 were members of families with more than 1 RA case. T he remainder were simplex cases. Conclusion, In this population, clini cal markers of severe RA were present in a majority of cases. The pres ence of familial aggregation for RA in the Pinna Indians suggests unde rlying genetic factors in disease pathogenesis.