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.