title: Risk Factors for the Development and Progression of Atlantoaxial Subluxation in Surgically Treated Rheumatoid Arthritis Patients, Considering the Time Interval between Rheumatoid Arthritis Diagnosis and Surgery.
abstract: OBJECTIVE
  Rheumatoid arthritis (RA) is a systemic disease that can affect the cervical spine, especially the atlantoaxial region. The present study evaluated the risk factors for atlantoaxial subluxation (AAS) development and progression in patients who have undergone surgical treatment.
  
  
  METHODS
  We retrospectively analyzed the data of 62 patients with RA and surgically treated AAS between 2002 and 2015. Additionally, we identified 62 patients as controls using propensity score matching of sex and age among 12667 RA patients from a rheumatology registry between 2007 and 2015. We extracted patient data, including sex, age at diagnosis, age at surgery, disease duration, radiographic hand joint changes, and history of methotrexate use, and laboratory data, including presence of rheumatoid factor and the C-reactive protein (CRP) level.
  
  
  RESULTS
  The mean patient age at diagnosis was 38.0 years. The mean time interval between RA diagnosis and AAS surgery was 13.6±7.0 years. The risk factors for surgically treated AAS development were the serum CRP level (p=0.005) and radiographic hand joint erosion (p=0.009). The risk factors for AAS progression were a short time interval between RA diagnosis and radiographic hand joint erosion (p<0.001) and young age at RA diagnosis (p=0.04).
  
  
  CONCLUSIONS
  The CRP level at RA diagnosis and a short time interval between RA diagnosis and radiographic hand joint erosion might be risk factors for surgically treated AAS development in RA patients. Additionally, a short time interval between RA diagnosis and radiographic hand joint erosion and young age at RA diagnosis might be risk factors for AAS progression.
authors.affiliation: Department of Neurosurgery, Hanyang University Medical Center, Seoul, Korea.
authors.forename: Min-Kyun
authors.initials: MK
authors.lastname: Na
authors.affiliation: Department of Neurosurgery, Hanyang University Medical Center, Seoul, Korea.
authors.forename: Hyoung-Joon
authors.initials: HJ
authors.lastname: Chun
authors.affiliation: Department of Neurosurgery, Hanyang University Medical Center, Seoul, Korea.
authors.forename: Koang-Hum
authors.initials: KH
authors.lastname: Bak
authors.affiliation: Department of Neurosurgery, Hanyang University Medical Center, Seoul, Korea.
authors.forename: Hyeong-Joong
authors.initials: HJ
authors.lastname: Yi
authors.affiliation: Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Korea.
authors.forename: Je Il
authors.initials: JI
authors.lastname: Ryu
authors.affiliation: Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Korea.
authors.forename: Myung-Hoon
authors.initials: MH
authors.lastname: Han
keywords: Atlantoaxial subluxation; Posterior cervical fusion; Rheumatoid arthritis