Prevalence and associated factors of anterior atlantoaxial luxation in a nation-wide sample of rheumatoid arthritis patients

Abstract

Objective: To estimate the prevalence of anterior atlantoaxial subluxation (AAS) in patients with rheumatoid arthritis (RA), and to analyse its association with disease markers.

Methods: Cross-sectional analysis of a cohort of RA patients randomly selected from the clinical registries of 34 centres. AAS, defined as an atlantoaxial displacement in cervical spine X-rays greater than 3 mm on flexion films, was actively searched for. Bivariate and multivariate analysis was performed to examine its association with clinical, functional, and treatment variables.

Results: AAS was found in 88 out of 736 patients with available cervical radiographs, (prevalence and 95% confidence interval [CI]: 12% [9.7-14.2]). The presence of AAS was highly associated with a Larsen score (0-150) over 50 (OR and 95% CI: 5.31 [2.68-10.55]), RA duration of more than 10 years (4.48 [2.70-7.44]), disease onset before age 50 (4.15 [2.42-7.12]), eye involvement (3.93 [1.63-9.46]), and previous RA related surgery (3.90 [2.46-6.19]). No association was found with rheumatoid factor. Multivariate analysis showed that a disease onset before the age of 50, the number of previous DMARD, and, above all, a Larsen score greater than 50 were important independent factors associated with AAS. There is a 33% increased risk for AAS every 10 units up in the Larsen score.

Conclusion: AAS is frequent in RA patients, particularly in those with markers of erosive disease.