Impact of comorbidities and extra-musculoskeletal manifestations on radiographic progression in ankylosing spondylitis.

Abstract

To examine whether baseline comorbidity burden and extra-musculoskeletal manifestations (EMMs) - psoriasis, uveitis, IBD-are associated with spinal radiographic progression in ankylosing spondylitis (AS). We analysed participants fulfilling modified New York criteria with ≥1 lateral cervical or lumbar radiograph. Radiographic progression was quantified using the modified Stoke AS Severity Score (mSASSS), excluding score 1 at each vertebral corner (range 0-48). Comorbidity count (22 self-reported conditions: 0,1,2,≥3) and ever-presence of each EMM at baseline were exposures. mSASSS change over time with exposure-time interactions was modelled using GEE; coefficients were rescaled to represent mean difference in progression (units/10 years). Models adjusted for baseline mSASSS, sex, symptom duration, CRP, HLA-B27, smoking, TNF inhibitor use, and number of EMMs or comorbidity count. Secondary analyses examined potential sex- and segment-specific effects. Among 1,150 individuals (mean age 44 years; 75% male; 84% HLA-B27 positive), 3,441 patient-years were analysed (median follow-up 2 years; median 2 radiographs). Compared with those with no comorbidities, progression was greater amongst patients with 2 (2.7 units/10 years; 95%CI 1.9-3.5) and ≥3 (2.3; 1.5-3.1) comorbidities. Uveitis (2.2 units/10 years; 1.3-3.0) and psoriasis (2.4 units/10 years; 1.4-3.5), but not IBD, were associated with greater progression. Sex-specific analyses suggested greater spinal progression in females than males with psoriasis. Cervical-predominant changes were seen with uveitis and psoriasis. Comorbidity burden, uveitis, and psoriasis are independently associated with greater spinal radiographic progression in AS. These readily identifiable features may inform risk stratification and targeted management strategies.