Effectiveness of biologic therapy on disease activity in ankylosing spondylitis: a BIOBADASER III observational study

Abstract

Background The advent of biologic therapy (BT) in ankylosing spondylitis (AS) has substantially benefited patients with inadequate response to conventional therapy. However, it is known patients with inadequeate response to a 1st BT have worse response to 2nd and further lines. Objectives To analyze the effectiveness of BT in biologic-naïve and biologic-experienced real-world AS patients, measuring response through change in activity indexes (ASDAS-CRP and BASDAI) and percentage of low activity and inactive disease at 12 months. Methods Data were obtained from BIOBADASER III, an ongoing observational longitudinal multicenter cohort of patients with rheumatic diseases treated with BT or targeted synthetic DMARDs. Patients were divided into 2 groups, according to their state before entering the study: BT-naïve (BTn) receiving their 1st BT, and BT-experienced (BTe) receiving their 2nd or further BT; regardless of the specific drug they received. Disease activity indexes (DAI) were collected at baseline and after 12 months of BT; mean and SD was calculated for each group and interpreted according to ASDAS disease activity states and, since not established, analogous categories previously used for BASDAI (<2 inactive, ≥2 <4 low, ≥4 <6 high, ≥6 very high)1. Clinical response was assessed by ASDAS improvement cut-offs (≥1.1 clinically important improvement (CII), ≥2 major improvement (MI)) and BASDAI CII (≥1.1)2, BASDAI change (Δ) ≥2 or BASDAI50. Results 846 patients, (29.3% women, mean age 47.6 years) were included, 422 BTn and 424 BTe. Mean DAI results (table 1): at baseline, AS had high disease activity by BASDAI (>4) and ASDAS (>2.1 to <3.5). At 12 months, disease activity was low on both groups (BASDAI<4, ASDAS >1.3 to <2.1), reaching BASDAI CII; ΔBASDAI≥2 was only achieved in BTn. No group reached BASDAI50. ASDAS CII was reached in all groups, but MI was not seen. Percentage of patients achieving low disease activity and inactive disease are summarized at table 2, being overall higher for the BTn compared to the BTe group. Conclusion The mean disease activity on patients starting biologic therapy is high. A clinically important improvement is met after 12 months of therapy, irrespectively of the index used or the prior use of biologics. The delta in DAI is bigger in the biologic-naïve group who receive the 1st BT. The biologic-naïve group also reaches a higher percentage of low disease activity and inactive disease. Further analysis is needed to see if these tendencies remain after separating the groups per type of biologic drug.