Risk factors for development and progression of atlantoaxial subluxation in Korean patients with rheumatoid arthritis.

We sought to evaluate the frequency of cervical spine (C-spine) involvement, and associated risk factors for this disorder and its progression in Korean patients with rheumatoid arthritis (RA). From 1995 to 2008, we recruited patients with RA attending the rheumatology clinic of a single tertiary care hospital, and evaluated 1,120 of the patients who had neck pain for C-spine involvement. A diagnosis of C-spine involvement was made in 28.6% of patients evaluated, and within this group, anterior atlantoaxial subluxation (AAS) and subaxial subluxation were found in 89.7 and 15%, respectively. Of the 1,120 patients, 570 patients were followed for more than 3 years. Comparing the clinical characteristics of 193 patients with C-spine involvement and 377 patients without C-spine involvement, we found the associations with female gender, RA diagnosis at or before age 45, erosive changes in hand or foot radiographs, C-reactive protein levels and erythrocyte sedimentation rates at the time of first visit, and combination disease-modifying anti-rheumatic drug (DMARD) therapy. We found using logistic regression analysis that significant predictors of C-spine involvement included erosion in hand or foot radiographs (OR = 2.22, p = 0.001) and RA diagnosis at or before age 45 (OR = 2.26, p < 0.001). Among 137 patients followed for more than 3 years, for whom at least two consecutive X-rays were available, we observed radiographic progression in 60.4%. Patients with and without radiologic evidence for cervical progression did not differ significantly in clinical characteristics. In conclusion, Korean patients with RA frequently show radiographic evidence for progressive involvement of the cervical spine. Significant risk factors for C-spine involvement may be associated with erosive peripheral joint disease and RA diagnosis at an early age.