Atlantoaxial Subluxation In Patients With Psoriatic Arthritis

Objective We aimed to investigate the prevalence and incidence of atlantoaxial subluxation (AAS) in psoriatic arthritis (PsA), identify associated risk factors, and describe the clinical and radiographic characteristics of affected patients. Methods We included individuals from our observational cohort of PsA, excluding those with a history of trauma or cervical spine surgery. We calculated prevalence and incidence of AAS, and we used descriptive statistics to summarize and compare baseline demographic and disease-related characteristics between patients with and without AAS. Additionally, we used Cox regression with time-varying covariates to identify factors linked to AAS development and performed multivariable GEE analysis to assess associations with AAS. Results Among 1,535 PsA patients, 34 (2.21%) were identified with AAS, including 20 at baseline and 14 during follow-up, with an incidence of 1.16 per 1000 person-years. Patients with AAS had higher rates of radiographic sacroiliitis (71.0%) and greater peripheral joint damage. Elevated ESR was observed in 86.7% of cases. Cox regression identified radiographic sacroiliitis (HR 6.61, 95% CI 1.64–26.67) as the strongest predictor of AAS, while male sex was associated with a lower hazard (HR 0.42, 95% CI 0.07–0.89). In GEE analysis, radiographic sacroiliitis (OR 3.64, 95% CI 1.6–8.24) and higher modified Steinbrocker scores were associated with AAS, whereas older age (OR 0.95, 95% CI 0.93–0.98) and male sex (OR 0.40, 95% CI 0.17–0.92) were associated with lower ORs. Conclusion AAS is an uncommon complication in PsA strongly associated with radiographic sacroiliitis and radiographic damage in peripheral joints.