The incidence of rheumatoid arthritis in Spain: results from a nationwide primary care registry

• Published in: Rheumatology (Oxford, England) Vol. 47; no. 7; pp. 1088 - 1092
• Main Authors: Carbonell, J., Cobo, T., Balsa, A., Descalzo, M. Á., Carmona, L.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.07.2008; Oxford Publishing Limited (England)
• Subjects: Adolescent; Adult; Age Distribution; Aged; Arthritis; Arthritis - diagnosis; Arthritis - epidemiology; Arthritis, Rheumatoid - epidemiology; Biological and medical sciences; Cohort studies; Disease occurrence; Diseases of the osteoarticular system; Early Diagnosis; Epidemiology; Female; Humans; Incidence; Inflammatory joint diseases; Male; Medical sciences; Middle Aged; Miscellaneous. Osteoarticular involvement in other diseases; Population studies; Primary care; Primary Health Care - statistics & numerical data; Registries; Rheumatoid; Sex Distribution; Spain - epidemiology; Europe; Spain; Rheumatoid; Early diagnosis; Disease occurrence; Cohort studies; Population studies; Registries; Arthritis; Epidemiology; Primary care; Incidence; Immunopathology; Diseases of the osteoarticular system; Rheumatology; Autoimmune disease; Inflammatory joint disease; Care; Chronic; Cohort study; Rheumatoid arthritis; Diagnosis
• ISSN: 1462-0324; 1462-0332
• DOI: 10.1093/rheumatology/ken205

Objective. To estimate the incidence of early arthritis (EA) and of RA in adults (>16 yrs) in Spain. Methods. Primary care physicians were instructed in the detection of new cases using a checklist. All cases were evaluated at EA units (EAUs) within 15 days of detection. ACR criteria for the classification of RA were assessed every 6 months thereafter. Results. In an area covering 4 342 378 inhabitants over the age of 16 yrs, 2467 patients were referred to the EAU, of whom 1063 fulfilled EA criteria (43.1%). After 6 months, 362 patients fulfilled RA criteria. The estimated annual incidence of EA was 25/100 000 population (95% CI: 23, 26). The annual incidence of RA was 8.3 cases/100 000 (95% CI: 7.5, 9.2): 11.3/100 000 in women (95% CI: 10.0, 12.8), and 5.2/100 000 in men (95% CI: 4.3, 6.3). The incidence of RA increased with age in both sexes. At the 6 months’ assessment, 187 (51.7%) of the patients with RA were RF positive. The presentation of RA was mainly polyarticular (n = 268; 74.0%). There were 701/1063 patients with EA who did not fulfil RA criteria by 6 months after the first rheumatologist visit. If all cases of undifferentiated arthritis (n = 118; 17%) became RA, the incidence would be in the range of 10 cases/100 000 population. Conclusions. RA incidence in Spain is in the lower range of published data. The incidence of EA is about three times that of RA.