Twenty-five year trends in prevalence of chronic bronchitis and the trends in relation to smoking

SummaryIntroductionThe present study examines how the trends in the prevalence of chronic bronchitis during the last three decades associate with changes in smoking habits during the same period.MethodsAltogether 47 896 subjects aged 25–74 years were examined in six independent cross-sectional population surveys repeated every five years between 1982 and 2007 in Finland. The presence of chronic bronchitis, smoking habits and other risk factors were measured by standard questionnaires.ResultsDuring the study, the prevalence of chronic bronchitis was significantly higher in men than in women. In men aged 25–64 years, the prevalence of chronic bronchitis decreased from 19% in 1982 to 13% in 2007 (p for trend