[Population distribution and clinical characteristics in rheumatoid arthritis patients with cervical spine instability]

OBJECTIVE: To investigate the population distribution of cervical spine instability in rheumatoid arthritis (RA) patients, and to analyze the clinical characteristics in RA patients with cervical spine instability. METHODS: A total of 439 RA patients who had completed cervical spine X-ray examination from Department of Rheumatology and Immunology of Peking University Shenzhen Hospital and Peking University Third Hospital from August 2015 to March 2019 were enrolled. The clinical data, laboratory data and cervical radiographic data were collected and analyzed by t-test, rank sum test and Chi-square test to clarify the clinical characteristics in the RA patients with cervical spine instability. RESULTS: Of the 439 RA patients, 80.9% (355/439) were female, with an average age of (52.9±13.9) years, a median duration of the disease was 60 months, the shortest history was 2 weeks, and the longest history was up to 46 years. 29.6% (130/439) of the RA patients showed cervical spine instability. Among them, 20 RA patients were complicated with two different types of cervical instability, the atlantoaxial subluxation (AAS) accounted for 24.6% (108/439), the vertical subluxation (VS) accounted for 7.3% (32/439) and the subluxial subluxations (SAS) accounted for 2.3% (10/439). The patients with cervical spine instability had a longer duration of disease [120 (36, 240) months vs. 48 (12, 120) months], a higher proportion of peripheral joint deformity (56.9% vs. 29.9%), and a higher visual analog scale (VAS) measuring general health score (4.89±2.49 vs. 3.93±2.38), a lower hemoglobin [(111.31±19.44) g/L vs. (115.56±16.60) g/L] and a higher positive rate of anti-cyclic citrullina-ted peptide (CCP) antibody (90.8% vs. 76.6%). There were no significant differences in gender, age, number of swollen joints, number of tenderness joints, erythrocyte sedimentation rate, rheumatoid factor level, 28-joint disease activity score, positive rate of anti keratin antibody, duration of glucocorticoid use and duration of disease modifying anti-rheumatic drugs use between the two groups. CONCLUSION: In the study, 29.6% of the RA patients showed cervical spine instability. RA patients with cervical spine instability had a long-term disease, a higher proportion of peripheral joint deformity, a higher VAS measuring general health score, a lower hemoglobin and a higher positive rate of anti-CCP antibody.