Among 657 persons who had an FEV1
of less than 80% of the predicted value
before 40 years of age, 174 (26%) had COPD after 22 years of observation, whereas
among 2207 persons who had a baseline FEV1
of at least 80% of the predicted
value before 40 years of age, 158 (7%) had COPD after 22 years of observation
(P