Factors associated with treatment intensification in patients with axial spondyloarthritis and high disease activity in clinical practice

Objective: To investigate which factors are associated with treatment intensification (TI) in axial SpA (axSpA) patients with high disease activity (HDA). Methods: Patients with axSpA and HDA [Ankylosing Spondylitis Disease Activity Score (ASDAS) ≥2.1] from the Dutch SpA-Net registry were included. TI was defined as: (i) higher dose or shorter interval of the same drug, (ii) switch from current drug to another due to inefficacy or (iii) addition of a new drug. Only anti-inflammatory drugs were considered. Primary determinants considered were ASDAS, Assessment of SpondyloArthritis international Society Health Index (ASAS HI) and physician global assessment (PhGA). Acceptable symptom state according to patient (PASS-patient) or physician (PASS-physician) were included in sensitivity analyses. Patient-centred and physician-centred logistic regression models were used to investigate the association between potential determinants and TI. Results: In total, 121 patients with HDA were included. TI was conducted in a minority (41/121, 33.9%), and mainly involved a switch or addition of a drug. In multivariable regression analyses, a higher ASDAS was associated with TI in the patient-centred model [odds ratio (OR)ASDAS = 1.94 (95% CI 1.00-3.74)]. However, in the physician-centred model, this association attenuated, and PhGA or PASS-physician were the primary factors associated with TI [ORPhGA = 1.71 (1.24-2.34); ORPASS-physician = 94.95]. Interestingly, patient-centred factors (ASAS HI/PASS-patient/education level) did not contribute to TI. Conclusion: In practice, treatment is intensified in a minority of axSpA patients with HDA. Physician-centred factors are associated with the decision to change treatment, independently of disease activity or patient perspective. Further research is needed to better understand these decisions.