Use of Analgesics in Osteogenesis Imperfecta in Denmark-A Nationwide Register-based Cohort Study

Osteogenesis imperfecta (OI) is a group of rare, hereditary diseases caused by mutations to the genes involved in the biosynthesis of collagen type 1. A cardinal feature of OI is the frequent occurrence of fractures. Individuals with OI often experience pain that is not related to fracture episodes. However, little is known about the use of analgesics among people with OI. We aim to examine the use of analgesics in Danes with OI as a measure of pain, using register-based data. This study is a Danish nationwide, population-based, and register-based cohort study. It includes all individuals registered with an OI diagnosis from January 1977 to December 2018, and a reference population matched by birth month, year, and sex. We examined the number of prevalent analgesic users over time and by age, the amount of analgesic use in Defined Daily Doses (DDDs), and the risk of initiating analgesics as well as treatment at a specialised pain centre during the observation period. We present the Sub Hazard Ratio (SHR) [95% confidence interval] for the endpoints comparing the OI cohort to the reference population. Lastly, we evaluated the changes in analgesic use related to fractures in the OI cohort and the proportion of long-term opioid users in both cohorts. A total of 905 individuals with OI and 4542 in the reference population were identified. There were more prevalent analgesic users (71.8% vs. 46.8%) in the OI cohort, with the number of users increasing over time and with age. Individuals in the OI cohort were more likely to initiate analgesics (SHR 1.86 [1.68-2.05]) and specialised pain care (SHR 5.8 [3.1-11.0]) than in the reference cohort. The use of analgesics, as measured in total DDDs, increased shortly after a fracture in the OI cohort but normalised to pre-fracture levels within 6 months. A higher proportion of the OI cohort had repeated dispensed prescriptions of opioids compared to the reference population. Individuals with OI are more likely to use analgesics and to use more analgesics-as measured by DDDs-than non-OI individuals.