To compare the impact of meeting specific classification criteria [modified New York (mNY), European
Spondyloarthropathy Study Group (ESSG), and Assessment of SpondyloArthritis international Society (ASAS) criteria] on anti-
tumor necrosis factor (anti-TNF)
drug retention, and to determine predictive factors of better
drug survival. All patients fulfilling the ESSG criteria for
axial spondyloarthritis (SpA) with available data on the axial ASAS and mNY criteria, and who had received at least one anti-TNF treatment were retrospectively retrieved in a single academic institution in Switzerland.
Drug retention was computed using survival analysis (Kaplan-Meier), adjusted for potential confounders. Of the 137 patients classified as having axial SpA using the ESSG criteria, 112 also met the ASAS axial SpA criteria, and 77 fulfilled the mNY criteria.
Drug retention rates at 12 and 24 months for the first
biologic therapy were not significantly different between the diagnostic groups. Only the small ASAS non-classified axial SpA group (25 patients) showed a nonsignificant trend toward shorter
drug survival. Elevated CRP level, but not the presence of bone marrow
edema on magnetic resonance imaging (MRI) scans, was associated with significantly better
drug retention (OR 7.9, ICR 4-14). In this cohort, anti-TNF
drug survival was independent of the classification criteria. Elevated CRP level, but not positive MRI, was associated with better
drug retention.