(099) Description of time trends in the of users of Janus kinase inhibitors in Sweden using a joinpoint regression approach

Background: Janus kinase inhibitors (JAKi) is a relatively new family of immune-modulating drugs, which inhibits the activity of the JAK family of enzymes. JAKi have been approved for the treatment of several chronic inflammatory disorders. A review of JAKi safety in the treatment of inflammatory disorders was conducted by the European Medicines Agency and concluded that JAKi should be used only if there is not a suitable alternative in individuals, over 65 years of age, with increased risk of major cardiovascular problems or cancer and who smokes. The review was concluded and endorsed on 23 January 2023 and was followed by updated product information for JAKi in March 2023.

Objectives: We aim to describe time trends in the number of users of JAKi, and identify potential trend changes using a joinpoint regression approach, in all individuals and in the subgroup over 65 years of age.

Methods: We studied the trend of JAKi prescribing in Sweden using publicly available aggregated data from the Swedish National Board of Health and Welfare’s website, from January 2021 until December 2023. We used the monthly count of patients who filled prescriptions of JAKi (Tofacitinib, Baricitinib, Filgotinib, Upadacitinib, and Abrocitinib) overall, by drug, by sex and in patients over 65 years of age. We described time trends using permutation joinpoint regression models (JP), which identifies segments in time, separated by changes in tendencies called joinpoints. Each segment is described with a monthly percent change (MPC) in prevalent use.

Results: The JP analysis of the number of patients considering all JAKi together in all ages showed a single increasing segment with a significant MPC of 1.56 (95%CI 1.43 - 1.71) without any joinpoint.
In the subgroup over 65 years old, the JP analysis showed a joinpoint in January 2023 (95%CI February 2022 - July 2023), showing 2 segments: an increasing segment until the joinpoint (MPC 0.86, 95%CI 0.51 - 1.62), and a decreasing segment after the joinpoint (MPC -1.24, 95%CI -4.57 - -0.16). The same pattern was observed in both sex strata by men and women, and by drugs in Filgotinib, and Upacitinib. Barecitinib and Tofacitinib showed only one segment with declining tendencies without joinpoints.

Conclusions: The JP analysis in the subgroup over 65 years of age showed a joinpoint in January 2023, while looking at the whole population without any age restriction, no joinpoint was identified. This indicates that the JP managed to identify the period when the safety recommendation was changed.
Since JAKi has newly approved indications and different new competing drugs at different times, exploring time trends by the drug may highlight the effect of the new recommendation on safety by the subgroup of JAKinib.