Microscopic gut inflammation in axial spondyloarthritis: a multiparametric predictive model

Objective To assess the rates and explore predictors of microscopic gut inflammation in a cohort of patients with axial and peripheral spondyloarthritis (SpA). Methods Ileocolonoscopy was performed in 65 patients with axial and peripheral SpA from the Gent Inflammatory Arthritis and spoNdylitis cohorT. Histopathological analysis and scoring were performed by an experienced pathologist. Results Overall, 46.2% of the patients with SpA showed microscopic gut inflammation. In axial SpA, the following parameters were independently associated with gut involvement: male sex (OR = 8.9, p = 0.035); high disease activity measured by the Bath Ankylosing Spondylitis Disease Activity Index (OR = 2.05, p = 0.032); restricted spinal mobility measured by the Bath Ankylosing Spondylitis Metrology Index (OR = 1.94, p = 0.009); and younger age (OR = 0.85, p = 0.013). No clear association was found for human leucocyte antigen-B27 status, presence of peripheral arthritis, enthesitis, uveitis, psoriasis, intake of non-steroidal anti-inflammatory drugs and family history of SpA. The prevalence of gut inflammation in non-radiographic axial SpA and ankylosing spondylitis was comparable. Conclusions The prevalence of microscopic gut inflammation in SpA remains unaltered over time. Younger age (shorter symptom duration), progressive disease, male sex and higher disease activity are independently associated with microscopic gut inflammation in axial SpA.