Objective: To determine trends in the incidence and clinical presentation of ankylosing spondylitis first diagnosed between 1935 and 1989 among residents of Rochester, Minnesota, and in the survival of the patients.
Methods: Population-based descriptive study.
Results: The overall age- and sex-adjusted incidence rate was 7.3 per 100,000 person-years (95% confidence interval 6.1-8.4). The rate tended to decline between 1935 and 1989, but there was little change in the age at symptom onset or diagnosis over the 55-year study period. Overall survival was not decreased up to 28 years following diagnosis.
Conclusion: These data indicate that there is a constancy in the epidemiologic characteristics of ankylosing spondylitis and suggest that previously study results indicating changes may have been due to biases in patient selection and study design.