title: Cervical spine involvement in rheumatoid arthritis over time: results from a meta-analysis.
abstract: BACKGROUND
  Complications in rheumatoid arthritis (RA) seem less common than they were years ago. The prevalence and progression of anterior atlantoaxial subluxations (aAASs), vertical subluxations (VSs), subaxial subluxations (SASs), and associated cervical myelopathy in RA over the past 50 years were determined.
  
  
  METHODS
  A literature search was performed by using Medline-OVID/EMBASE, PubMed, and Scopus (from 1960 to June 21, 2014). Prevalence studies were included if the sample size was at least 100 or the prevalence/progression of cervical subluxations was reported. Study quality was assessed by using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. Prevalence of cervical subluxations was calculated for each study. Student's t test and meta-regression were used to evaluate for significance.
  
  
  RESULTS
  In total, 12,249 citations were identified and 59 studies were included. The prevalence of aAAS decreased from 36% (95% confidence interval (CI) 30% to 42%) before the 1980s to 24% (95% CI 13% to 36%) in the 2000s (P = 0.04). The overall prevalence rates were 11% (95% CI 10% to 19%) for VS, 13% (95% CI 12% to 20%) for SAS, and 5% (95% CI 3% to 9%) for cervical myelopathy, and there were no significant temporal changes. Rates of progression of aAAS, VS, and SAS were 4, 6, and 3 lesions per 100 patients per year, respectively. The incidence of new or progressive cervical myelopathy was 2 cases per 100 patients with known cervical subluxations per year.
  
  
  CONCLUSIONS
  Since the 1960s, only aAAS has decreased dramatically. It is still more than twice as common as VS or SAS. No temporal changes in the development of cervical myelopathy in affected patients with RA were noted. The progression rates of cervical subluxations and myelopathy were unchanged over time.
authors.affiliation: Schulich School of Medicine & Dentistry, Western University of Canada (formerly University of Western Ontario), St. Joseph Health Care, 268 Grosvenor Street, London, ON, N6A 4 V2, Canada. xzhang2013@meds.uwo.ca.
authors.forename: Tony
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Schulich School of Medicine & Dentistry, Western University of Canada (formerly University of Western Ontario), St. Joseph Health Care, 268 Grosvenor Street, London, ON, N6A 4 V2, Canada. janet.pope@sjhc.london.on.ca.
authors.forename: Janet
authors.initials: J
authors.lastname: Pope
mesh_terms: D001172:Arthritis, Rheumatoid / Q000150:complications*; D001268:Atlanto-Axial Joint; D002574:Cervical Vertebrae / Q000473:pathology; D006801:Humans; D004204:Joint Dislocations / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D013118:Spinal Cord Diseases / Q000453:epidemiology* / Q000209:etiology