Fracture Risk and Its Prevention Patterns in Korean Patients with Polymyalgia Rheumatica: a Retrospective Cohort Study

BACKGROUND: To evaluate the incidence of fractures and fracture risk factors in Korean patients with polymyalgia rheumatica (PMR). METHODS: All PMR patients who visited a rheumatology clinic at a tertiary referral hospital between March 2005 and March 2018 were retrospectively assessed. We estimated bone mineral density (BMD) screening rate within 6 months of the first visit and classified the patients according to the performance and results of BMD screening. Incidence rates (IRs) of fractures were calculated in each group and risk factors for fractures were identified using Poisson regression analysis. RESULTS: A total of 95 PMR patients with median (interquartile range) age of 64.0 (56.0–72.0) years were included. Baseline BMD was assessed in only 55.8% of these patients (n = 53); 24 patients with osteoporosis, 20 with osteopenia, and 9 with normal BMD. During 433.1 person-years (PYs) of observation, 17 fractures occurred in 12 patients (IR, 3.93 [95% confidence interval (CI), 2.46–6.26]/100 PYs); 8.32 (95% CI, 4.09–16.90)/100 PYs in the osteopenia group, 3.40 (95% CI, 1.30–8.90)/100 PYs in the osteoporosis group, and 3.37 (95% CI, 1.53–7.39)/100 PYs in the no BMD test group. Risk factors for fractures were female sex, advanced age (≥ 65 years), longer follow-up duration, initial glucocorticoid dose ≥ 10 mg/day, and higher cumulative glucocorticoid dose over the first 6 months. CONCLUSION: The incidence rate of fractures in Korean patients with PMR was 3.93/100 PYs. Female sex, advanced age, longer follow-up duration, and increased glucocorticoid dose are risk factors for osteoporotic fracture.