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

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.