Are clinical measures influenced by various ethnic origins in Iranian patients with ankylosing spondylitis? A pilot study

Background: Ankylosing spondylitis (AS) may manifest with heterogeneous patterns according to ethnic origins. The purpose of this study was to describe the influence of various Iranian ethnic origins on clinical measures in patients with AS. Methods: 0ne hundred sixty-three AS patients diagnosed by modified New York 1984 criteria were enrolled consecutively. The patients were classified into Fars, Turk, Kord, Lor and other ethnic origins. Several clinical measures were described and compared between the ethnic origins. Results: The highest and the lowest finger to floor distance was observed for Fars ethnicity (20.4±14.8) and other ethnicities (5.9±8.1), respectively (P=0.04). The frequency of severe decrease in cervical slope was significantly different between various ethnicities (P=0.025). The most and the least frequency of severe decrease in cervical slope was observed in Fars patients (61.3%) and other ethnicities (20%), respectively. The frequency of severe thoracic kyphosis was significantly dissimilar between various ethnicities (P=0.006). The most and the least frequency of severe increase in thoracic kyphosis was observed in Fars (68.8%) and Lor patients (25%), respectively. A significant relationship was seen only between other ethnicities and finger to floor distance, lateral lumbar flexion, chest expansion and BASDAI (P < 0.05). Conclusion: Clinical expression variations in AS disease might be influenced by various Iranian ethnic origins. A larger sample size with other Iranian ethnicities (Baluch, Arab, etc) is required to clear the definite relationship between Iranian ethnicities and clinical expression.