title: Global prevalence of ankylosing spondylitis.
abstract: OBJECTIVE
  For effective health care provision, knowledge of disease prevalence is paramount. There has been no systematic endeavour to establish continent-based AS estimates, however, prevalence is thought to vary by country and background HLA-B27 prevalence. This study aimed to estimate AS prevalence worldwide and to calculate the expected number of cases.
  
  
  METHODS
  A systematic literature search was conducted. Prevalence data were extracted and used to calculate the mean prevalence by continent and the expected number of cases based on country-specific prevalence (or, if missing, the prevalence from neighbouring countries). A second estimate was made using the prevalence from countries with similar HLA-B27 prevalences if a country-specific prevalence estimate was not available.
  
  
  RESULTS
  The mean AS prevalence per 10,000 (from 36 eligible studies) was 23.8 in Europe, 16.7 in Asia, 31.9 in North America, 10.2 in Latin America and 7.4 in Africa. Additional estimates, weighted by study size, were calculated as 18.6, 18.0 and 12.2 for Europe, Asia and Latin America, respectively. There were sufficient studies to estimate the number of cases in Europe and Asia, calculated to be 1.30-1.56 million and 4.63-4.98 million, respectively.
  
  
  CONCLUSIONS
  This study represents the first systematic attempt to collate estimates of AS prevalence into a single continent-based estimate. In addition, the number of expected cases in Europe and Asia was estimated. Through reviewing the current literature, it is apparent that the continuing conduct of epidemiological studies of AS prevalence is of great importance, particularly as diagnostic capabilities improve and with the recent development of the criteria for axial SpA.
authors: Epidemiology Group, Institute of Applied Health Sciences, School of Medicine and Dentistry, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD, UK. r05lm0@abdn.ac.uk.
authors: Linda E
authors: LE
authors: Dean
authors: Gareth T
authors: GT
authors: Jones
authors: Alan G
authors: AG
authors: MacDonald
authors: Christina
authors: C
authors: Downham
authors: Roger D
authors: RD
authors: Sturrock
authors: Gary J
authors: GJ
authors: Macfarlane
mesh_terms: D000349:Africa / Q000453:epidemiology; D001208:Asia / Q000453:epidemiology; D005060:Europe / Q000453:epidemiology; D014943:Global Health; D015796:HLA-B27 Antigen / Q000235:genetics; D006801:Humans; D007843:Latin America / Q000453:epidemiology; D009656:North America / Q000453:epidemiology; D015995:Prevalence; D013167:Spondylitis, Ankylosing / Q000453:epidemiology* / Q000235:genetics
chemical_list: D015796:HLA-B27 Antigen
keywords: ankylosing spondylitis; epidemiology; prevalence; spondyloarthropathies; systematic review