Prevalence and clinical characteristics of ankylosing spondylitis in Iceland - a nationwide study

Clin Exp Rheumatol. May-Jun 2010;28(3):333-40. Epub 2010 Jun 23.


Objectives: To determine the prevalence and clinical characteristics of ankylosing spondylitis (AS) in the Icelandic population, which carries a high prevalence of HLA-B27.

Methods: A nationwide search was performed by screening hospital records and private rheumatology services for cases of AS in association with an on-going genetic study. Individuals diagnosed with AS according to the modified New York criteria were asked to participate in the study by answering a standardised questionnaire and to undergo an interview and clinical evaluation.

Results: A total of 256 individuals fulfilled the modified New York classification criteria for AS (169 male, 87 female); 84% of these individuals were HLA-B27 positive vs. 15% in the population (p<10-16). Of those contacted 223 patients (87.1%) answered the standardised questionnaire and were included in the study. The prevalence of AS in Iceland was 0.13% (CI 0.11-0.14%). A highly conservative prevalence number, based only on clinically evaluated patients, gave prevalence of 0.10% (CI 0.09-0.11%). Mean age at onset of symptoms was 24+/-8 years and at diagnosis 32.1+/-10.2 for male and 34.2+/-10.1 for female patients (not significant). Female patients more often had arthritis in peripheral joints and male patients were more often diagnosed with iritis. Prostatitis was experienced by 27% of male patients.

Conclusions: AS is less common in the Icelandic population than reported in various Caucasian populations with a similar prevalence of HLA-B27.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age of Onset
  • Female
  • HLA-B27 Antigen / genetics*
  • Humans
  • Iceland / epidemiology
  • Incidence
  • Male
  • Prevalence
  • Severity of Illness Index
  • Spondylitis, Ankylosing / epidemiology*
  • Spondylitis, Ankylosing / genetics*
  • Spondylitis, Ankylosing / physiopathology
  • Surveys and Questionnaires
  • Whites / statistics & numerical data
  • Young Adult


  • HLA-B27 Antigen