British Axial Spondyloarthritis Inception Cohort (BAxSIC): a protocol for a multicentre real-world observational cohort study of early axial spondyloarthritis.

Objectives: Timely diagnosis remains a challenge in axial SpA (axSpA). In addition, data are scarce on the impact of diagnostic delay and disease progression in affected individuals. The British Axial Spondyloarthritis Inception Cohort (BAxSIC) study aims to investigate the impact of newly diagnosed axSpA, the natural history of the disease and the effect of diagnostic delay on disease outcomes.
Methods: BAxSIC is a prospective, multicentre, observational study. Eligible participants are adults (≥16 years of age), with a physician-confirmed diagnosis of axSpA in the 6 months prior to study entry, recruited from secondary and tertiary rheumatology centres in the UK. Participants will be followed up for 3 years, with in-person visits at baseline and 24 months. In addition, patient self-reported assessments will be recorded remotely via the online electronic case report form (eCRF) at 6, 12, 18, 30 and 36 months.
Results: The first patient was enrolled in BAxSIC in June 2023. Recruitment is currently ongoing and is planned to end in June 2026. Initial results will be available in 2027. Since opening, the trial has undergone two protocol amendments.
Conclusion: The BAxSIC study is the first inception cohort designed to investigate the impact of diagnostic delay on clinical presentation and long-term functional outcomes in patients with axSpA in the UK. With an innovative, patient-led virtual longitudinal data collection model, data generated from this study will help inform and improve the care of people newly diagnosed with axSpA.
Trial Registration: ClinicalTrials.gov (http://clinicaltrials.gov), NCT05676775.
(© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)