Pattern of ankylosing spondylitis in an Iranian population of 98 patients.

The prevalence and pattern of ankylosing spondylitis (AS) can vary from country to country, according to genetic and environmental factors. This study aims to analyze the patterns of disease in a population of Iranian patients with AS. We performed a prospective study (2002-2007) analyzing 98 patients with diagnosis of AS according to the modified New York criteria. Selected patients underwent complete clinical (initial symptom, axial and peripheral involvement, heel enthesitis, extra-articular manifestations) and radiological (sacroiliac, lumbar, thoracic, and cervical spine) investigations, and these data were compared with sex, age at onset, and HLA-B27. There was predominance of men (71.4%), adult onset (>16 years, 90.8%), and positive HLA-B27 (73.4%). Family history of AS was noted in 14.3% of the patients. The predominant initial symptoms were inflammatory low back pain (44.2%). Radiological findings included syndesmophytes in 34.7% and "bamboo spine" in 16.3% of patients. Acute anterior uveitis was noted in 44.9% of patients. Male sex was associated with involvement of shoulder (P = 0.001). Female sex and juvenile-onset AS were associated with extra-articular involvement. Positive HLA-B27 was associated with hip involvement (P = 0.042) and adult-onset AS (P = 0.035). Analysis of the patterns of disease in this population of 98 southern Iranian patients with AS revealed that female sex and juvenile-onset AS were associated with extensive extra-axial involvement; and HLA-B27 was associated with hip involvement.