ABSTRACT

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are relatively frequent events that have a major impact on patient well-being, both at the time of the event and in the long term. Recent observations have clearly shown that therapeutic interventions can, to some extent, prevent exacerbations as well as modify their course. This has created both the opportunity and the imperative to develop more effective interventions to mitigate the burden of acute exacerbations, which, in turn, has created a need for precise and operationally tractable definitions. Crucially, a definition of exacerbations is needed that permits the events to be adequately quantified, both in terms of frequency and severity. This has proven difficult for a variety of reasons. First, exacerbations are heterogeneous. In addition, they are primarily a patient-reported event. Objective confirmatory tests based on biomarkers have yet to be satisfactorily developed. The problem of definition is exacerbated by the distinction between definition and diagnosis. As pointed out by Prof. Gordon Snider:

It is important to realize the difference between the definition of a disease and its diagnostic criteria (1). The defining characteristics of a disease are the common properties specifying the group of abnormal persons on whom the description of the disease is based. The definition of a disease is important in communication.