The relative contributions of nature and nurture in chronic obstructive pulmonary disease

The causal relationship between cigarette smoking and chronic bronchitis and emphysema has been established beyond reasonable doubt. There is good evidence that a number of other host and environmental factors may also be involved but the exact nature of the relationships is not yet understood. It is therefore not yet possible to use historical information such as total cigarette consumption, place of residence and occupation to construct a profile of the high-risk or susceptible smoker. It is clear, however, that in only a small proportion of smokers, probably fewer than 10 percent, clinical airflow obstruction develops, and in a small proportion of these the crippling form of the disease develops. Until more is learned about the interrelation of the factors involved in COPD, the practical approach to identifying the smoker in whom clinical airflow obstruction is going to develop is to follow all smokers with spirometric tests at regular intervals (for example, annually). Those persons whose test results fall in the low normal range in early or midadult life and those who show an unexpectedly rapid decline in function should be considered to fall in the high-risk category.