Asthma Cases Continue to Rise: Why?

Mark T. O'Hollaren, MD


January 25, 2007

The Asthma Epidemic

Eder W, Ege MJ, von Mutius E
N Engl J Med. 2006;355:2226-2235

The study authors have written a very clear and helpful summary of the current state of the asthma epidemic. Some of the trends in regard to asthma have been disturbing. For example, they pointed out that the US Centers for Disease Control and Prevention noted an increase in the prevalence of asthma in children in the United States from 3.6% in 1980 to 5.8% in 2003. Only pneumonia and injuries are responsible for more hospitalizations among those under 18 years of age in the United States.[1] More striking increases in the prevalence of asthma have been seen in other countries. For example, approximately 1 in 5 children in Australia in 1964 were reported by their parents to have symptoms of asthma during their first 7 years of life; by 1990 that number had increased to nearly 1 in 2.[2]

The study authors also pointed out that no single instrument can be used to reliably diagnose asthma in any given individual. They noted that asthma is a diagnosis made clinically by combining the patient history, physical examination, and spirometry (including confirmation of reversible airway obstruction). Atopy is strongly associated with asthma, and in some countries the incidence of atopy is increasing; this may or may not be accompanied by a concomitant increase in the incidence of asthma. The study authors also noted that exposure to passive cigarette smoke has consistently been shown to increase the incidence of asthma. Children whose parents smoke are more likely to develop asthma compared with those whose parents do not smoke.

Although air pollution has been shown to exacerbate asthma in those who already have the disease, it is not clear whether it contributes to the de novo development of the disease. Conflicting data were noted in regard to the role of dust mite exposure or pets early in life and the relationship of that exposure to the development of asthma. There is also increasing evidence linking asthma and obesity, with a relationship between body mass index and the incidence of asthma being demonstrated in both adults and children. Although there was some mention in the past that use of antibiotics in childhood may be related to the development of asthma, subsequent studies have not substantiated this finding. weak association exists between the use of acetaminophen and the development of asthma, but not enough to warrant avoidance of the drug.

The study authors, in this erudite summary of an extremely complex area of medicine, noted that asthma is really a syndrome rather than a single, distinct entity. They related asthma to anemia, which may have many causes contributing to the final clinical finding, and stressed that disease presentation results from the interaction of a genetically unique individual with his or her environment.



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