ab22407

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

A. Naranjo¹, L. Carmona², D. Gavrila³, A. Balsa⁴, M.A. Belmonte⁵, X. Tena⁶, C. Rodríguez-Lozano¹, R. Sanmartí⁷, I. González-Álvaro⁸, and the EMECAR Study Group⁹*

¹Rheumatology Department, Hospital Dr. Negrín, Las Palmas; ²Rheumatology Department, Hospital Clínico San Carlos, Madrid; ³Epidemiology Unit of the Spanish Society of Rheumatology, Madrid; ⁴Rheumatology Department, Hospital La Paz, Madrid; ⁵Rheumatology Department, Hospital General de Castellón, Castellón; ⁶Rheumatology Department, Hospital Germans Trias i Pujol, Badalona; ⁷Rheumatology Department, Hospital Clinic i Provincial, Barcelona; ⁸Rheumatology Department, Hospital de la Princesa, Madrid; ⁹Sociedad Española de Reumatología, EMECAR Study Group

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.

Key words
Rheumatoid arthritis, cervical spine, atlantoaxial luxation.

*The members of the EMECAR Study Group are listed at the end of this paper.
This study was supported by the medical department of Aventis Pharma, SA.
Please address correspondence and reprint requests to: Antonio Naranjo, MD, Hospital Dr. Negrín, Rheumatology Department, 35020 Las Palmas, Spain.
E-mail: anarher@gobiernodecanarias.org