(B-101) Monitoring pediatric prescribing of baricitinib in the United Kingdom during a period prior to approval for use in patients < 18 years of age

Background: Baricitinib received approval to treat UK adults with moderate to severe active rheumatoid arthritis, moderate to severe atopic dermatitis and severe alopecia areata in 2017, 2020, and 2022, respectively. Prior to the authorization for treatment of juvenile idiopathic arthritis and pediatric AD in 2024, baricitinib was not authorized for any pediatric use in the UK. Therefore, understanding pediatric prescribing of baricitinib prior to regulatory approval for use in this population was important for pharmacovigilance and risk management.

Objectives: This observational cohort study was designed to assess baricitinib prescribing to UK pediatric patients (age < 18 years) from April 2017 to April 2022.

Methods: This study utilized data from CPRD Aurum and CPRD GOLD, two UK primary care electronic medical records databases. Patients with valid registration in the CPRD databases were indexed into the cohort on the day of their earliest recorded baricitinib prescription. The CPRD databases were combined for analysis and patients present in both Aurum and GOLD data were deduplicated. The total number of patients prescribed baricitinib and the proportion of these patients who were ˂18 years of age at index were described. Identified pediatric patients were further analyzed to determine age, sex, and year of earliest recorded baricitinib prescription. The study was approved via CPRD’s Research Data Governance (protocol number 18_220).

Results: During the study period, 1471 patients prescribed baricitinib were identified in CPRD Aurum and 130 in CPRD GOLD. After deduplicating 74 patients present in both databases, 1527 patients (adults and pediatric) remained in the final study cohort. Of these, 12 were < 18 years of age at the time of their earliest CRPD-recorded baricitinib prescription. Therefore, 0.79% (95% CI 0.41% to 1.37%) of baricitinib prescribing was to pediatric patients. These 12 pediatric patients had a mean (SD) age of 12.08 (5.23) years and a median (interquartile range [IQR]) age of 14 (8.5, 16.5) years; 75% were female (n=9). The greatest annual number of pediatric baricitinib prescriptions (n=6) occurred between July 2020 to June 2021.

Conclusions: The small proportion of patients in the CPRD databases prescribed baricitinib who were < 18 years of age did not suggest that further risk management was needed. This work also provides a relevant case study for the utility of CPRD, a GP EMR, in the analysis of prescription patterns for medications traditionally prescribed by specialists.