Objective: To determine the prevalence of ankylosing spondylitis (AS) and related spondyloarthritides (SpA) in an adult urban population of Izmir, Turkey.
Methods: A survey was conducted of 2887 subjects aged 20 years or over, selected by cluster sampling. Those who responded positively to the screening questions were contacted by 2 rheumatologists and evaluated in detail to establish presence of AS (modified New York criteria) or related SpA (ESSG criteria).
Results: In the initial screening, 2835 subjects participated; 422 were considered screening-positive and a telephone interview was done with 328 (78%). Based on their clinical history, 145 subjects were invited to the hospital and 120 (83%) agreed to do so. After detailed evaluation, 31 subjects were classified as having SpA (including 14 with AS). The age- and sex-adjusted prevalence was estimated to be 0.49% for AS (95% CI 0.26-0.85), and 1.05% for SpA (95% CI 0.70-1.50). The prevalence of AS was 0.54% in men (95% CI 0.19-1.20) and 0.44% in women (95% CI 0.19-0.88), and that of SpA was 0.88% in men (95% CI 0.42-1.59) and 1.22% in women (95% CI 0.73-1.89).
Conclusion: This epidemiological study suggests a high prevalence (0.49%) of AS in an adult urban population from western Turkey, which equals that of rheumatoid arthritis in the same population. The overall prevalence of SpA, including AS, was 1.05%. A minimal male predominance was noted among AS patients, which disappeared among the whole group of patients with SpA.