Effect of Biologics in Subgroups of Axial Spondyloarthritis Based on Magnetic Resonance Imaging and C-Reactive Protein: A Systematic Review and Meta-Analysis

Objective: To determine if the efficacy of biologics differ based on magnetic resonance imaging (MRI) and C-reactive protein (CRP) findings. Methods: We compared four subgroups (MRI+/CRP+, MRI+/CRP−, MRI−/CRP+, MRI−/CRP−) from randomized controlled trials (RCTs). A comprehensive database search was performed to include axial spondylarthritis (axSpA; both radiographic axSpA [r-axSpA] and nonradiographic axSpA [nr-axSpA]) RCTs with treatment efficacy reported by different MRI and CRP subgroups. Study-specific disease activity scores (at 12-16 weeks) were pooled using a random-effects model and compared between the four subgroups. Results: Five trials (all nr-axSpA) were included: three with tumor necrosis factor inhibitors (TNFi, N = 729) and two with interleukin-17 inhibitors (IL-17i, N = 794). TNFi and IL-17i showed efficacy based on the Assessment of Spondyloarthritis International Society 40 (ASAS40) and Bath Ankylosing Spondylitis Disease Activity Index 50 (BASDAI50) in all MRI and CRP subgroups, except the CRP−/MRI− subgroup, which had a single study with only 39 patients. There was no statistically significant difference between the four subgroups in terms of patients achieving ASAS40 (P = 0.60, I² = 0%) or BASDAI50 (P = 0.27, I² = 23.9%). The number needed to treat was three for the CRP+/MRI+ and CRP+/MRI− subgroups and six for the CRP−/MRI+ and CRP−/MRI− subgroups. All trials had a low risk of bias. Between-study heterogeneity was low to moderate. Sensitivity analyses comparing TNFi or IL-17i versus placebo similarly showed no difference between subgroups in terms of ASAS40 (TNFi, P = 0.57; IL-17i, P = 0.28) and BASDAI50 (TNFi, P = 0.37; IL-17i, P = 0.18). Conclusion: In this systematic review, there was no statistically significant difference between the four subgroups in terms of efficacy based on ASAS40 or BASDAI50.