Factors Associated With the Absence of Cervical Spine Instability in Rheumatoid Arthritis: A >10-Year Prospective Multicenter Cohort Study.

OBJECTIVE

To identify factors associated with the absence of cervical spine instability in patients with rheumatoid arthritis (RA).

METHODS

Cervical spine instability was defined as the presence of at least one of the following: atlantoaxial subluxation, vertical subluxation of the axis, or subaxial subluxation. In 2001-2002, 634 enrolled outpatients with "classical" or "definite" RA underwent a radiographic cervical spine checkup. In 2012-2013, 233 (36.8%) prospectively underwent routine clinical follow-ups with a >10-year radiographic evaluation. The prevalence and independent predictive factors for no instability were analyzed by multivariable logistic regression. Next, 85 of 292 outpatients (29.1%) without baseline cervical spine instability completed consecutive >5-year and >10-year radiographic examinations. The incidence and predictors for no new development of instability were assessed similarly.

RESULTS

Among 233 patients, those without cervical spine instability decreased from 114 (48.9%) to 47 (20.2%) during >10 years. Steinbrocker peripheral joint destruction stages I-II (odds ratio [OR], 3.797; p=0.001), no corticosteroid administration (OR, 2.700; p=0.007), and no previous joint surgery (OR, 2.480; p=0.020) were predictors for no instability. Then, 33 of 85 (38.8%) consecutively followed patients without baseline cervical spine lesions did not develop instability throughout. Steinbrocker stages I-II (OR, 5.355; p=0.005) and no corticosteroid therapy (OR, 3.868; p=0.010) were predictors for no new onset of instability. C-reactive protein (CRP) level≤1.0 mg/dL was marginal in both models (n=233 [OR, 2.013; p=0.057], n=85 [OR, 2.453; p=0.075]).

CONCLUSION

Steinbrocker stages I-II, no corticosteroids, no previous joint surgery, and possibly CRP ≤1.0 mg/dL are factors associated with >10-year absence of cervical spine instability in RA.