Epidemiology of ankylosing spondylitis in Northwest Greece, 1983-2002

Objective. To investigate the incidence and the prevalence of ankylosing spondylitis (AS) in a defined area of northwest Greece with a total population of about 500 000 inhabitants. Methods. AS cases were recorded from (i) in- and out-patients referred to the rheumatology clinics of the Ioannina university hospital and the Ioannina general hospital, and (ii) patients referred to private rheumatologists practising in the study area. An incident case was defined as any patient with AS, diagnosed during the period between 1 January 1983 and 31 December 2002 who were resident in the study area for at least 1 yr before the diagnosis. A prevalent case was defined as any patient with AS who was a resident of the study area on 31 December 2002. Diagnosis was based on the modified New York criteria for AS. Population data were based on the 1981, 1991 and 2001 National Censuses. Results. A total of 113 cases were diagnosed among the population of the area studied during the period 1983-2002. Men constituted a 4.65-fold higher number of patients than women, and had a significantly higher mean age at diagnosis. All patients presented bilateral sacroiliitis, 40 patients (35.9%) had peripheral joint involvement and 15 patients presented extra-articular manifestations (13.27%). HLA-B27 antigen was found in 80.5% of our patients. The age-adjusted mean annual incidence rate for the population aged greater than or equal to16 yr was 1.5 cases per 10(5) inhabitants [95% confidence interval (CI) 0.4-2.5], and the age-adjusted prevalence rate on 31 December 2002 was 29.5 cases per 10(5) inhabitants (95% CI 25.9-33.1). The incidence rates were higher in the age group 35-44 yr for men and in the age group 25-34 yr for women. Conclusion. The incidence and prevalence of AS in the area studied were significantly lower than in other white populations and higher than in the Japanese population.