Objectives
To identify factors that drive high biologic usage in a real-world clinical setting.
Methods
We collected retrospective data from all patients with axial spondyloarthritis who had received biologic therapy for their disease in our designated specialised clinic in a tertiary centre. Our outcome measure was ‘high biologic usage’ (defined as the use ≥ 3 biologic drugs/tsDMARDs and/or ≥ 2 biologic pathways targeted for therapy. We analysed patient age, sex, BMI, the concomitant presence of chronic widespread pain (CWP), HLA-B27 positivity, radiographic-SpA, extra-articular manifestations, time to initiate biologic therapy from diagnosis and disease activity measures (BASDAI, pain VAS and CRP) to identify predictors.
Results
Out of a total of 227 patients in our axSpA cohort, 166 (71% male, mean age 48 years) had received biologic therapy. Of these, 62 (27%) met the definition of high biologic usage. Our analysis identified four factors that were significantly associated with our outcome: HLA-B27 positivity (positive correlation), time to start biologic from diagnosis (negative correlation), concomitant chronic widespread pain (negative correlation) and aggregate BASDAI burden while on biologics (positive correlation).
Conclusion
There was a significant cohort of axial spondyloarthritis patients who met our criteria of ‘high biologic usage’. HLA-B27 positivity, the early requirement of biologics in the disease course and higher aggregate BASDAI burden were associated with greater biologic usage. A concomitant diagnosis of chronic widespread pain has the confounding effect of being associated with a higher BASDAI though lower biologic usage, exemplifying the impact this diagnosis has on clinical decision making. Key messages: Patients with axSpA receiving high-cost therapies form distinct clusters based on response to treatment, and the presence or absence of CWP. Concurrent CWP in axSpA can introduce cognitive bias when deciding on the need for change in therapy, especially given the subjective nature of assessments including BASDAI. AxSpA patients with CWP are likely to represent a distinct subtype of disease who display worse clinical outcomes and are likely to require alternative management strategies.