Asthma: the epidemic has ended, or has it?

All truths are easy to understand once they are discovered; the point is to discover them. A sthma, a chronic inflammatory lung condition with acute episodes of bronchoconstriction and exacerbation, is associated with considerable patient morbidity, a diminution of productivity, and an increase in health-care utilization. Throughout the 1980s and 1990s, there was a clear perception that asthma prevalence was increasing. This perceived trend prompted concern about a possible " asthma epidemic. " Worldwide efforts to promote awareness about asthma diagnosis, prevention, and treatment followed the publication of these concerns. 1 In the United States, the Healthy People 2010 initiative 2 has clearly targeted improving asthma care, awareness , and education as key objectives. In this issue of CHEST (see page 1993), Vargas et al report on asthma trends in Mexico from 1991 to 2001, analyzing health claims data from a nationwide database representing approximately one third of the Mexican population. Asthma incidence (ie, newly diagnosed asthma cases determined by first-time family physician visits), emergency department visits for asthma, and hospital discharges with asthma listed as a primary diagnosis steadily increased from 1991 to 1995. This increment was followed by a plateau (from 1995 to 1997) and a subsequent decline (from 1997 to 2001). It appears that in Mexico, at least for a third of the population with health insurance, there is an early trend toward decreased health-care utilization by asthmatic patients. This may, in part, be due to a decrease in the incidence of asthma in this population. Can the same be said about the incidence of asthma in the United States and other countries? Are we continuing to observe a worldwide increase in asthma incidence or has the asthma epidemic truly stabilized, and perhaps even decreased? Moreover, are we even using the proper tools to detect any changes in the trend? The answers to these questions are conflicting, in part due to the lack of uniformity in definitions and the nature of epidemiologic survey tools used to monitor asthma trends. The principal source of data for the estimation of asthma prevalence in the United States is the National Health Interview Survey (NHIS), 3 a multipurpose health survey conducted by the National Center for Health Statistics, Centers for Disease Control and Prevention, to study the health of the civilian, noninstitutionalized, household population of the United States. The NHIS undergoes periodic revision , to reflect the changing nature of the …