Rheumatoid arthritis in the indigenous qom population of Rosario, Argentina: aggressive and disabling disease with inadequate adherence to treatment in a community-based cohort study.

To describe the baseline and follow up epidemiological/clinical characteristics of rheumatoid arthritis (RA) in a community-based cohort of the qom population. RA (ACR criteria) patients identified (n = 40) or not (n = 25) in the previous study were included. Baseline and follow-up visits (3, 6, and 12 months) were performed. Treatment adherence and modification, disability (Health Assessment Questionnaire Disability Index-HAQ-DI), and Disease Activity [DAS-28 (ESR)] were ascertained. At 12 months, complete and incomplete lost to follow-up patients were identified. The estimated RA prevalence was 3%. The patients' mean (SD) disease duration was 110.5 (17.9) and their median delay in diagnosis 30.4 (IQR 52.8) months; mean (SD) age and years of formal education were 39.8 (1.6) and 5.3 (SD 0.3); 58 (89.2%) were female, and 89.2% were seropositive. At baseline, their mean DAS-28 (ESR) was 4.8 (SD 0.9) with 67.7% having high disease activity and 32.3% moderate; 76.9% reported HAQ-DI ≥ 0.8. At 12 months, three patients have died; 13 (20.9%) were "completely" and 19 (30.6%) "incompletely" lost to follow-up. There were favorable changes over time for disease activity (p ˂ 0.001), HAQ-DI (p ˂ 0.001), and treatment modifications (p ˂ 0.001) but no changes in treatment adherence (p = 0.260). The main cause of lost to follow-up was migration. This population has one of the highest RA prevalence rate reported. Patients had an aggressive and disabling disease, with poor adherence to treatment. Improvements of clinical parameters over time were observed.