Background TNF alpha blockers (TNFb) are effective in spondyloarthritis (SpA); primary inefficacy (defined by lack of treatment response in the first three months of treatment) is unfrequent and has been little explored. Who are these patients who have primary inefficacy, and do they respond to a switch?
Objectives To assess the rate of primary inefficacy of TNFb therapy in SpA, to compare demographic and disease characteristics between responders and non-responders and to assess the retention rate of the second TNFb in case of switching.
Methods Study design: Systematic retrospective study from one tertiary care rheumatology department over 5 years. Patients: All patients with SpA (as confirmed by a rheumatologist) starting a TFNb. Demographic factors (age and gender), disease characteristics (symptom duration, B27 status, radiographic sacro-iliitis) and disease activity at TNFb initiation (BASDAI, BASFI, TNFb indication for axial symptoms, CRP) were compared between non responders at 3 months and other patients using univariate tests. For patients with primary inefficacy, survival curve of the second TNFb was assessed in case of switching.
Results Among 222 patients who started a TNFb, 27 patients (12%) stopped the first TNFb for primary inefficacy. Compared to the other patients, these patients were more often women (48% versus 27%, p=0.04), had an older age at TNFb initiation (46 yrs vs 40, p=0.04), had more often a TNFb indication not related to the axial symptoms (29% vs 14%, p=0.007), had a higher BASFI (68 versus 42, p=0.001) and had more often a normal CRP (50% vs 22%, p=0.008). No differences were noted for B27 positivity (overall, 78%) and self-reported activity of disease. Among the 27 patients with primary inefficacy, a second TNFb was prescribed for 16 patients (59%). Primary inefficacy of the second TNFb was observed in 7 patients (44% of 16) and the survival rate at one year for the second TNFb was 44%.
Conclusions Primary inefficacy of the first TNFb is rare in SpA (12%); these patients had a less clear pattern of SpA (ie had less signs of definite and axial SpA); furthermore a second TNFb if prescribed was often also not efficacious. These results suggest primary inefficacy of TNFb in SpA may lead to reconsidering the initial diagnosis; in particular the place of fibromyalgia-like symptoms should be further assessed.
Disclosure of Interest None declared