title: Factors That Predict Risk of Cervical Instability in Rheumatoid Arthritis Patients.
abstract: METHODS
  Retrospective data analysis.
  
  
  OBJECTIVE
  To identify factors affecting the atlantodental interval, the Ranawat value, and subaxial translation after rheumatoid arthritis (RA) diagnosis. In addition, factors predictive for cervical spine instability (CSI) development after RA diagnosis were examined.
  
  
  BACKGROUND
  Development of CSI affects the prognosis and mortality of RA patients. Previous studies described that obesity is associated with reduced radiographic joint damage in RA patients. We hypothesized that body mass index (BMI) is also associated with radiographic cervical damage in RA patients.
  
  
  METHODS
  Cervical radiographs were taken at full flexion, neutral position, and full extension to measure the geometric length of the anterior atlantodental interval, the Ranawat value, and subaxial translation. These values were entered into multivariable linear regression analysis based on potential associated factors. Hazard ratios were calculated to identify independent factors predictive of CSI.
  
  
  RESULTS
  Of the patients diagnosed with RA between January 2005 and August 2015, 1611 who underwent at least one cervical radiograph were included. After adjusting for sex, age, BMI category, CSI, rheumatoid factor, and RA medication, multivariate analysis revealed that the risk of atlantoaxial subluxation in the underweight and normal BMI groups was about 1.6-fold (hazard ratio, 1.63; 95% CI, 1.10-2.43; P = 0.015) and 1.7-fold higher, respectively, than that in the obese group, and that the risk of vertical subluxation was about 2.5-fold (hazard ratio, 2.52; 95% CI, 1.32-4.83; P = 0.005) higher in the underweight group than in the obese group. We also found that the rheumatoid factor positivity was a predictive risk factor for CSI development.
  
  
  CONCLUSIONS
  We identified risk factors predictive for CSI occurrence after RA diagnosis through cervical radiograph assessment. We found that BMI was an independent predictor for development of CSI. Further large-scale prospective studies are required to confirm these findings.
  
  
  METHODS
  3.
authors: Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Gyonggi-do, Korea.
authors: Myung-Hoon
authors: MH
authors: Han
authors: Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Gyonggi-do, Korea.
authors: Je Il
authors: JI
authors: Ryu
authors: Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Gyonggi-do, Korea.
authors: Choong Hyun
authors: CH
authors: Kim
authors: Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Gyonggi-do, Korea.
authors: Jae Min
authors: JM
authors: Kim
authors: Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Gyonggi-do, Korea.
authors: Jin Hwan
authors: JH
authors: Cheong
authors: Department of Neurosurgery, Hanyang University Medical Center, Wangsimni-ro, Seongdong-gu, Seoul, Korea.
authors: Koang Hum
authors: KH
authors: Bak
authors: Department of Neurosurgery, Hanyang University Medical Center, Wangsimni-ro, Seongdong-gu, Seoul, Korea.
authors: Hyoung Joon
authors: HJ
authors: Chun
authors: Department of Neurosurgery, Hanyang University Medical Center, Wangsimni-ro, Seongdong-gu, Seoul, Korea.
authors: Hyeong-Joong
authors: HJ
authors: Yi
authors: Department of Rheumatology, Hospital for Rheumatic Diseases, Hanyang University Medical Center, Wangsimni-ro, Seongdong-gu, Seoul, Korea.
authors: Jae Bum
authors: JB
authors: Jun
authors: Department of Neurosurgery, Asan Medical Center, Olympic-ro, Songpa-gu, Seoul, Korea.
authors: Jae Woo
authors: JW
authors: Chung
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000000981:diagnostic imaging* / Q000453:epidemiology; D015992:Body Mass Index; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000097:blood / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012217:Rheumatoid Factor / Q000097:blood; D012307:Risk Factors
chemical_list: D012217:Rheumatoid Factor