Characteristics and burden of disease in patients with radiographic and non-radiographic axial Spondyloarthritis: a comparison by systematic literature review and meta-analysis

Objectives To compare the clinical characteristics, burden of disease (eg, disease activity, function, quality of life), treatment modalities and treatment effect in patients with radiographic and non-radiographic axial Spondyloarthritis (r-axSpA and nr-axSpA). Methods A systematic literature review (2009-2018) was performed using the participants, intervention, comparator and outcomes methodology. Studies reporting outcomes (clinical presentation, burden of disease, treatment modalities and treatment effect) of both r-axSpA and nr-axSpA were included. A pooled analysis was performed (standardised means difference and relative risk for continuous and binary variables, respectively) and random or fixed effects methods were used depending on the heterogeneity of the studies. Results 60 studies out of 787 references were included. Pooled analysis showed that, compared with patients with nr-axSpA, patients with r-axSpA were more frequently men (69.6% vs 53.6%), smokers (37.7% vs 31.1%) and had higher mean disease duration (8.6 vs 5.0 years) and longer time to diagnosis (6.1 vs 4.2 years). Peripheral manifestations were more prevalent in nr-axSpA, while uveitis and structural damage on MRI of the sacroiliac joints were more prevalent in r-axSpA. C-reactive protein and the Bath Ankylosing Spondylitis Mobility Index were higher in r-axSpA, while Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index and Ankylosing Spondylitis Quality of Life were similar in both groups. No significant differences were found with regard to treatment effect. Conclusions Patients with r-axSpA and nr-axSpA share a similar clinical presentation except for peripheral involvement, which is more prevalent among nr-axSpA. Except for a more impaired mobility in r-axSpA, both groups showed a comparable burden of disease, treatment modalities and treatment effect.