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 spondylarthritis (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: 1) higher dose or shorter interval of the same drug, 2) switch from current drug to another due to inefficacy, or 3) 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 (PhGA). Acceptable symptom state according to patient (PASS-patient) or physician (PASS-physician) were included in sensitivity analyses. Patient-centered and physician-centered 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-centered model (ORASDAS = 1.94, [95%CI 1.00-3.74]). However, in the physician-centered 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-centered 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-centered 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.