Abstract
Background: The course of development of smoking related lung diseases, particularly emphysema, is not well characterized.
Methods: We have followed a birth cohort of 1037 New Zealanders from childhood to age 26, by which age 47% had initiated smoking, and 36% were continuing smokers. We recorded symptoms, spirometry, and smoking history at serial assessments. Pulmonary diffusing capacity (DCO) was measured at age 26 in 895 participants.
Results: In males, there was a progressive decrease in DCO (percent predicted) related to smoking exposure, being 106.2% in non-smokers, and 102.3%, 100.4%, 99.9% and 90.9% respectively in the lowest to highest quartiles of pack-year exposures. For females, these figures were 107.6%, 102.1%, 97.8%, 98.8% and 91.4% respectively. There was a highly significant relationship between pack-years of smoking and DCO (males, p = 0.0175; females, p = 0.0007), but little effect on airway function.
Conclusions: A progressive decrement observed in DCO in smokers may reflect early emphysema, apparent by age 26. The dose-response relationship with pack-years argues against suggestions that smoking affects only a "susceptible population".