ABSTRACT
Medical practitioners are most accustomed to a categorical approach to the definition of disease; patients are either healthy or they are not. However, some conditions such as hypertension and, of more relevance to this chapter, chronic obstructive pulmonary disease (COPD) do not always lend themselves to clear definition as to the onset of ‘‘disease.’’ Infectious diseases are, in general, easier to understand as processes readily distinguishable from normality. An invasive organism attacks the host and results in a self-limited illness, which is terminated by cure or death. The appreciation of the presence of a disease is greatly facilitated by the short time course of the process. In its advanced stages COPD can be diagnosed easily by the medical practitioner, but because it is a disease that has an insidious onset, there is inevitably a period when the lung can be considered to be in a transition state between health and disease. Identifying this transition phase and understanding the factors that determine the progression from health to disease has the potential to allow us to identify susceptible persons. Such knowledge would help the physician to more effectively discourage smoking and would facilitate the development of markers for the evaluation of early interventions designed to protect the lungs against damage. In this chapter we will review the pathophysiology of COPD in its transition phase and the methods that have been developed to attempt to detect ‘‘early’’ dis-
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ease. We will speculate on some of the pathological features that may distinguish susceptible individuals from those who are not.
