Risk factors for cervical spine instability in patients with rheumatoid arthritis.

Positivity for ACPA was a significant risk factor for C-spine instability, and AAS was remarkably correlated to the early initiation of biologic DMARDs, a surrogate index of poor long-term outcomes. Key Points • The presence of antibodies against citrullinated proteins was a strong risk factor for C-spine instability in patients with rheumatoid arthritis. • Atlantoaxial subluxation was significantly associated with early initiation of biologic DMARDs, a surrogate index of poor long-term outcome.