Incidence, prevalence and treatment burden of polymyalgia rheumatica in the UK over two decades: a population-based study.

OBJECTIVE: Polymyalgia rheumatica (PMR) is the most common inflammatory rheumatic disease in older people. Contemporary estimates of the incidence and prevalence are lacking, and no previous study has assessed treatment patterns at a population level. This study aims to address this.

METHODS: We extracted anonymised electronic medical records of patients over the age of 40 years from the Clinical Practice Research Datalink in the period 1990-2016. The absolute rate of PMR per 100 000 person-years was calculated and stratified by age, gender and calendar year. Incidence rate ratios were calculated using a Poisson regression model. Among persons with PMR, continuous and total duration of treatment with glucocorticoids (GC) were assessed.

RESULTS: 5 364 005 patients were included who contributed 44 million person-years of follow-up. 42 125 people had an incident diagnosis of PMR during the period. The overall incidence rate of PMR was 95.9 per 100 000 (95% CI 94.9 to 96.8). The incidence of PMR was highest in women, older age groups and those living in the South of England. Incidence appears stable over time. The prevalence of PMR in 2015 was 0.85 %. The median (IQR) continuous GC treatment duration was 15.8 (7.9-31.2) months. However, around 25% of patients received more than 4 years in total of GC therapy.

CONCLUSIONS: The incidence rates of PMR have stabilised. This is the first population-based study to confirm that a significant number of patients with PMR receive prolonged treatment with GC, which can carry significant risks. The early identification of these patients should be a priority in future research.