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

Abstract

Objective: To examine whether baseline comorbidity burden and extra-musculoskeletal manifestations (EMMs)—psoriasis, uveitis, IBD—are associated with spinal radiographic progression in AS. Methods: We analysed participants fulfilling modified New York criteria with one or more 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: none, one, two, three or more) and ever-presence of each EMM at baseline were exposures. mSASSS change over time with exposure-time interactions was modelled using generalized estimating equations; 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. Results: Among 1150 individuals (mean age 44 years; 75% male; 84% HLA-B27 positive), 3441 patient-years were analysed (median follow-up 2 years; median two radiographs). Compared with those with no comorbidities, progression was greater amongst patients with two (2.7 units/10 years; 95% CI 1.9–3.5) and three or more (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. Conclusion: 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.