Background If anti TNF alpha therapy response has been well evaluated and established for patients meeting NY criteria and/or MRI sacroiliitis in randomized clinical trials, only scarce data is available for patients without structural damage of the sacroiliac joint or inflammation.
Objectives To estimate the frequency of use and the treatment effect of anti TNF alpha therapy in early axial Spondyloarthritis (SpA )in daily practice, and compare this effect with regard of the presence of structural damage and objective signs of inflammation.
Methods Study design: prospective, multi-centre, observational study. Patients: 708 patients with early (<3years symtom duration) inflammatory back pain (IBP) suggestive of SpA (DESIR cohort). Statistical analysis: Frequency of use of anti TNF alpha therapy: estimation of the percentage of patients receiving anti TNF alpha therapy over the first 2 years of follow-up (Kaplan Meier technique). Treatment effect: patients receiving anti TNF alpha therapy were matched with patients not receiving anti TNF alpha therapy at a 1:1 ratio according to a propensity score. Moreover, the results were adjusted to the baseline BASDAI, BASFI and CRP levels. Missing data were handled by the last observation carried forward technique. Short-term (after at least 8 weeks under anti TNF alpha therapy) efficacy endpoint was ASAS40.
Results Of the 708 enrolled patients, 203 (28.7%) received at least one anti-TNF drug during follow-up. Of these patients, 127 (62.6%) presented with either X-ray sacroiliitis (67, 33.1%), MRI sacroiliitis (82, 40.4%) or CRP abnormality (83, 40.9%), and 72 (35.5%) without any objective sign of inflammation nor structural damage at the baseline visit for initiation of anti TNF alpha therapy. Data for assessment of the primary endpoint was only available in 197 of the patients receiving anti TNF therapy. Therefore efficacy analyses were only performed in 394 patients (e.g. 197 patients receiving anti TNF therapy + 197 patients receiving usual daily care). An ASAS40 response was observed more frequently after treatment with anti TNF alpha therapy than usual daily care (31.8% vs 23.7 %, p=0.0003, [OR= 2.76 (1.67-4.56)]).
No significant interaction between treatment effect and the presence of objective signs of inflammation was found with regard to the ASAS 40 short term response: the magnitude of the treatment effect (delta ASAS40 response percentage) was similar (73.7% OR=2.69 [1.47-4.95] vs. 71.9%OR=2.33 [0.92-4.95]) in the patients with vs. without any sign of inflammation or structural damage. However, the magnitude of the response was different (37.7% vs. 21.7% and 18.4% vs. 10.7%after anti TFN alpha therapy and after any other usual care in the groups with vs. without objective sign of inflammation or structural damage respectively).
Conclusions This study: 1/shows the high frequency of use of anti TNF alpha therapy in early axial SpA in daily practice 2/confirms the efficacy of anti TNF alpha therapy in comparison to any other daily care modalities 3/suggests that such treatment effect does exist regardless of objective sign of structural damage or inflammation 4/ suggests that patients without sign of inflammation are more refractory to treatment whatever this treatment modality is.
Disclosure of Interest None Declared