Thirty-year cumulative incidence of chronic bronchitis and COPD in relation to 30-year pulmonary function and 40-year mortality: a follow-up in middle-aged rural men.
OBJECTIVE
To describe the 30-year cumulative incidence of chronic bronchitis and COPD in relation to smoking habits. The effect of chronic bronchitis on pulmonary function and mortality was also examined.


METHODS
Middle-aged men belonging to two rural Finnish cohorts of the Seven Countries Study (n = 1,711 in 1959) were followed up for up to 40 years until 2000. Standard questionnaires were used to measure chronic bronchitis, and repeated spirometry was used to evaluate pulmonary function during the 30 years. Forty-year mortality data were examined.


RESULTS
The cumulative incidence of chronic bronchitis and COPD was 42% and 32%, respectively, in continuous smokers, compared to 26% and 14% in ex-smokers and 22% and 12% in never-smokers. During the follow-up, subjects with chronic bronchitis had on average 252 mL (95% confidence interval, 211 to 293 mL) lower forced expiratory volume than those without it. The decrease in forced expiratory volume attributable to chronic bronchitis was most pronounced in those with persistent symptoms and in smokers. In subjects with chronic bronchitis, all-cause mortality was increased by a hazard ratio of 1.30 (95% confidence interval, 1.02 to 1.65). Smokers with chronic bronchitis who decreased their daily cigarette consumption increased their median life span by 2.4 years.


CONCLUSIONS
The lifetime risk of chronic bronchitis among smokers is approximately two in five, and almost one half of smokers who have chronic bronchitis also acquire COPD. Chronic bronchitis is related to earlier death, also in never-smokers, probably partly through a rapid decline in pulmonary function.
Pelkonen
Margit
M
University of Kuopio, Department of Public Health and General Practice, PO Box 1627, FIN-70211 Kuopio, Finland. Margit.Pelkonen@uku.fi
Notkola
Irma-Leena
IL
Nissinen
Aulikki
A
Tukiainen
Hannu
H
Koskela
Heikki
H
D000328:Adult; D000368:Aged; D001991:Bronchitis / Q000175:diagnosis / Q000401:mortality*; D002423:Cause of Death; D003430:Cross-Sectional Studies; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000401:mortality*; D012016:Reference Values; D012424:Rural Population / Q000706:statistics & numerical data*; D012907:Smoking / Q000009:adverse effects / Q000401:mortality*; D016540:Smoking Cessation / Q000706:statistics & numerical data; D016019:Survival Analysis; D015996:Survival Rate