Postal survey on asthma, chronic bronchitis and respiratory symptoms among adult Estonians and non-Estonians (FinEsS-study)

BACKGROUND: According to the data of the population census held in Estonia in 1989, the resident population consisted of 61.5% Estonians and 38.5% non-Estonians, the majority of them being Russians--30.3%. The aim of this study was to investigate the prevalence of asthma, chronic bronchitis and respiratory symptoms among the adults in these ethnic groups. METHODS: The study was a postal survey, similar in design to parallel studies currently in progress in Finland, Estonia and Sweden (FinEsS). RESULTS: The prevalence of physician-diagnosed asthma was 2.0%, being similar in men and women and in both Estonians and non-Estonians. The prevalence of physician-diagnosed chronic bronchitis was 10.5%. Compared with the non-Estonian population, the prevalence was much lower among Estonians (7.9% vs. 13.5%, p<0.001). Such a difference in prevalence was observed in all age groups. The high prevalence of chronic bronchitis in non-Estonians could be related to more extensive smoking habits, smoking indoors and probably ETS exposure. The defined OR between non-Estonians vs. Estonians after correcting for the influence of smoking habits, area of domicile, age, gender, and socioeconomic group was 1.30. A similar pattern of differences between Estonians and non-Estonians was observed in respiratory symptoms. CONCLUSION: This study revealed that the prevalence of physician-diagnosed asthma in Estonians and non-Estonians was the same. Physician-diagnosed chronic bronchitis was more frequent in non-Estonians than in Estonians. A significant difference was determined in the prevalence of respiratory symptoms, especially among those common to chronic bronchitis. The differences remained significant after correction for possible confounders.