Study objectives: To evaluate the distribution of
airways obstruction in a general population sample.
Methods: Cross-sectional epidemiologic survey of a general
population sample living in Po Delta area (North Italy). Data on
respiratory symptoms, diseases, and risk factors were collected through
standardized interviewer-administered questionnaires. Lung function
tests were performed, with criteria for defining airways obstruction
based on the 1995 European Respiratory Society (ERS) statement
(FEV1/vital capacity ratio < 88% predicted and < 89%
predicted in men and women, respectively), “clinical” criteria
(FEV1/FVC ratio < 70%), and the 1986 American Thoracic
Society (ATS) statement (FEV1/FVC ratio < 75%).
Results: A total of 1,727 subjects aged > 25 years
investigated from 1988 to 1991 were included. Prevalence rates of
airways obstruction for subjects 25 to 45 years old and subjects ≥ 46
years old were as follows: ERS, 10.8% and 12.2%; clinical, 9.9% and
28.8%; and ATS, 27% and 57%, respectively. When considering only
moderate/severe obstruction, the rates were as follows: ERS, 0.4% and
3.6%; clinical, 0.3% and 4.4%; and ATS, 0.5% and 5.2%,
respectively. The trend was confirmed after stratifying for smoking
habit and the presence/absence of respiratory symptoms/diseases. The
highest specificity and predictive value for any respiratory
symptom/disease was shown by the ERS, and the lowest was shown by the
ATS criterion, while the reverse was true for sensitivity; overall
accuracy was slightly lower for the ATS criterion. Multiple logistic
regression models indicated a higher number of significant associations
with known risk factors for airways obstruction according to clinical
and ATS criteria than ERS criterion.
prevalence of COPD in a general population depends very much on the
criterion used for definition of airways obstruction. Further research
is needed to reach a standardized and epidemiologically consistent
criterion for airways obstruction.