Incidence and Disease Course of Polymyalgia Rheumatica During Two Decades: A Nationwide Study Across Health Care...

A new algorithm enables the identification of patients with polymyalgia rheumatica (PMR) across health care sectors in Denmark. We estimated annual incidence rates from 2003 to 2024 and described the disease course, including the occurrence of late-onset giant cell arteritis (GCA) and prednisolone or prednisone (PDN) treatment.

A Danish nationwide, population-based cohort study was conducted using data linked at the individual level. Cases were identified among people ages 50 years or older between January 1, 2003, and November 1, 2024.

A total of 51,401 patients were identified, including 24,456 from primary care and 26,945 from secondary care. The age-standardized incidence of PMR was 112 per 100,000 people (95% confidence interval [CI] 110.8-112.8). During the study period, the incidence declined by 53% in primary health care and increased by 30% in secondary health care, resulting in an overall decline of 12%. Among patients with PMR, GCA occurred at a rate of 5.4 (95% CI 5.1-5.7) per 1,000 patient-years, with a median of 68 days (interquartile range 10-602) from PMR diagnosis. Overall, 28% and 22% of patients were still treated with PDN after 5 and 10 years, with a median daily dose of 4.1 and 5.5 mg of PDN, respectively.

The increasing incidence of PMR in secondary health care was exceeded by the declining incidence in primary health care. Most late-onset GCA developed within the first year after PMR diagnosis. Many patients continued treatment with PDN for 5 to 10 years, indicating a need for earlier use of concomitant therapies.