Early diagnosis of ankylosing spondylitis: an introduction to the newly designed Iran criteria for ankylosing spondylitis.

More than 14 years of clinical practice in rheumatology led the author to develop his experience-based criteria for early ankylosing spondylitis (AS) diagnosis. This study aims to introduce this new set of criteria, Iran criteria for ankylosing spondylitis, and to assess its sensitivity in comparison with 1984 modified New York criteria. A cost-effective diagnostic approach towards AS diagnosis is also proposed. The criteria score the patients according to the findings in history and physical examination, imagings and HLA-B27 testing. Sensitivity analysis was performed in a retrospective manner after reviewing the medical records of 120 patients at the outpatient Rheumatology Clinic of the author (private sector), regarding clinical diagnosis by a single rheumatologist as the gold standard. The sensitivity was separately measured for disease durations of 2, 2-5, 5-10 and more than 10 years. Iran criteria for AS recorded a sensitivity of 100 % in all disease durations. However, the sensitivity of 1984 modified New York criteria was 48.39 % in early stages of the disease and increased to 92.10 % for disease duration of more than 10 years. Iran criteria for AS provide a highly sensitive instrument for detecting AS in its early and late, clinical and subclinical, radiographic and pre-radiographic stages as well as atypical forms.