P194 Prescribing of bisphosphonates and their impact on the risk of fractures in patients with polymyalgia rheumatica (PMR) in England: a cohort study and target-trial in the Clinical Practice Research Datalink Aurum

Abstract Background/Aims PMR is a common indication for long-term glucocorticoid (GC) treatment with real-world data on GC treatment in PMR showing that one quarter of patients continue them for >4 years. People with PMR have a 63% increased risk of fracture compared with age- and sex-matched controls and this risk is GC-dose related. Prescription of bisphosphonates alongside GCs is recommended for people with PMR at highest risk of fracture but overall rates of prescribing of these medications are low. It is not known whether those at greatest risk receive these preventative medications or whether there is unwarranted variation in care. Whilst there is evidence that bisphosphonates reduce the risk of GC-induced osteoporosis and vertebral fractures, there are no trials assessing the impact of bisphosphonates on fracture risk specifically in people with PMR. We addressed these evidence-gaps, describing prescribing patterns of bisphosphonates in people with PMR and their impact on rates of fragility fractures using national primary care data. Methods Using data from Clinical Practice Research Datalink Aurum we defined a population of people aged ≥50, diagnosed with PMR between January 2010-March 2022, and prescribed GCs. Two stages were used. Stage 1: Bisphosphonate prescriptions were characterised as prevalent (pre-PMR diagnosis), incident (at diagnosis), or late (post-diagnosis, but whilst still on GCs). We considered age, gender, and deprivation and stratified by risk factors for fractures. Stage 2: A target trial approach assessed the effect of bisphosphonates on fragility fractures. “Time zero” was the latter of date of first prednisolone prescription within 21 days of PMR diagnosis and PMR diagnosis date. People were excluded if they were on bisphosphonates before this date. Differences in probability of outcomes were estimated, adjusting for confounders. Follow-up was for a maximum of 5 years since time zero. Results Stage 1: 43,091 people were included. 32.5% who had additional risk factors for fracture were not prescribed bisphosphonates. Women and those in least deprived quintiles were more likely to be prescribed bisphosphonates. Stage 2: 41,826 people were included. The probability of a fragility fracture was 1.40%, 95% CI (1.10%, 1.70%), if someone was treated with a bisphosphonate for 12 months and 2.32%, (2.12%, 2.52%), if untreated over the same period; average treatment effect 0.915% points, (0.560%, 1.27%). Conclusion Many people with PMR who are at higher risk of fractures from their GC treatment do not receive bisphosphonates. There is variation in prescribing by gender and levels of socioeconomic deprivation. In people with PMR treated with GCs, bisphosphonates reduce the risk of fragility fracture. These findings suggest that practice could be improved and can be used to inform shared decision making between patients and clinicians. Disclosure H. Twohig: None. D. Jenkinson: None. J. Bailey: None. S. Hider: None. I. Scott: None. S. Muller: None.