The epidemiology of asthma

As noted earlier, the clinician and the epidemiologist are in many respects in similar positions in terms of our current understanding of asthma. Through the efforts of the pharmaceutical industry the practitioner has a much wider range of therapeutic tools available to manage reversible airways disease. B-agonists are more specific, have a longer duration of action, minimizing the potential for abuse and coincident toxicity. Theophylline preparations are long-acting and therapeutic drug levels can be accurately assessed. Inhaled corticosteroids provide the opportunity to reduce the negative side aspects of hormonal therapy. Unfortunately, with all these tools, the morbidity and mortality of asthma have not been decreased. In fact, it may be that the disease is a greater worldwide health problem than it was a generation ago. Similarly, epidemiologic research has provided us with increasingly meaningful information, not only of the prevalence of the disease, but with recent longitudinal studies, the factors which impact upon disease remission and relapse. Whether we separate the wheezing syndromes into separate categories of wheezy bronchitis, asthmatic bronchitis, and asthma is probably less important than our understanding of a disease entity which is characterized by bronchial hyper-reactivity in response to a variety of stimuli. The most encouraging aspects of recent epidemiologic research have been the selection of representative populations, using standardized methods, from which significant conclusions can be drawn. At the least, these studies have confirmed and extended our knowledge of a disease that we still do not fully understand. Woolcock et al.[56], and others, have included inhalation challenge testing into their epidemiologic protocols in an attempt to add physiologic assessments to the more traditional symptom complexes. Unfortunately, even this addition has not solved the problem of an asthma diagnosis in the older adult population whose irreversible airways obstructive disease is a confounding variable. Even in younger subjects, as reported by Townley et al.[14], a gradation of responses to methacholine inhalation in atopic subjects, may make the identification of asthmatics more difficult than initially thought. The fact that ex-asthmatics appear to retain their hyper-responsiveness, however, could make inhalation challenge a valuable tool in longitudinal epidemiologic research. What can epidemiologic studies contribute in the future?.(ABSTRACT TRUNCATED AT 400 WORDS)