Incidence and Prevalence of Polymyalgia Rheumatica and Giant Cell Arteritis in a Healthcare Management Organization in Buenos Aires, Argentina.

OBJECTIVE: To estimate incidence and prevalence of polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) in a university hospital-based health management organization (Hospital Italiano Medical Care Program) in Argentina. METHODS: Overall and sex-specific incidence rates (IRs) and prevalence were calculated (age ≥ 50 yrs). Incidence study followed members with continuous affiliation ≥ 1 year from January 2000 to December 2015. Diagnosis as per the 2012 European Alliance of Associations for Rheumatology/American College of Rheumatology (ACR) criteria for PMR or the ACR 1990 criteria for GCA. Prevalence was calculated on January 1, 2015. RESULTS: There were 176,558 persons who contributed a total of 1,046,620 person-years (PY). Of these, 825 developed PMR, with an IR (per 100,000 PY) of 78.8 (95% CI 73.4-84.2) overall, 90.1 (95% CI 82.9-97.2) for women, and 58.9 (95% CI 51.1-66.6) for men. Ninety persons developed GCA; the IR was 8.6 (95% CI 6.8-10.4) overall, 11.1 (95% CI 8.5-10.6) for women, and 4.2 (2.2-6.3) for men. There were 205 prevalent PMR cases and 23 prevalent GCA cases identified from a population of 80,335. Prevalence of PMR was 255 per 100,000 (95% CI 220-290) overall, 280 (95% CI 234-325) for women, and 209 (95% CI 150-262) for men; and the prevalence of GCA was 28.6 per 100,000 (95% CI 16.9-40.3) overall, 36.4 (95% CI 20.1-52.8) for women, and 14.2 (95% CI 0.3-28.1) for men. CONCLUSION: This is the first study of incidence and prevalence of PMR and GCA in Argentina. There were similarities and differences with cohorts from other parts of the world, but population-based epidemiologic studies in Latin America are needed.