Dennis K. Ledford; Richard F. Lockey

Disclosures

Curr Opin Allergy Clin Immunol. 2013;13(1):78-86. 

In This Article

Obesity

Obesity is common and increasing in prevalence worldwide. Obesity is generally defined by BMI, weight in kilogram divided by height in meters squared. Normal weight is defined as less than 25kg/m2, overweight, 25–30kg/m2, and obesity, greater than 30kg/m2. There are some concerns with this definition as central obesity may have more influence on health than total weight. Fat cells appear to modify inflammation and the role of adipocytes varies according to the type of fat or location of the cell.[29,30]

Relationship With Asthma

Multiple studies have attempted to characterize the association of increased body weight and asthma in both children and adults. The majority of peer-reviewed articles in the literature demonstrate a relationship with obesity and both the development and increased severity of asthma. In most of these papers, obesity precedes asthma.[31,32] The National Asthma Survey, published in 2008 and reporting data from 3095 participants, describes a persistence of symptoms, increased work absence, greater use of inhaled beta agonists and corticosteroids, and decrease in asthma control in individuals with greater body mass compared with normal weight asthmatic patients.[33] The mechanism by which obesity influences asthma or asthma symptoms is not established, with possibilities including a modified inflammatory response, increased asthma symptoms due to weight and deconditioning, functional effects on breathing mechanics or decreased response to inhaled corticosteroids.[32,34] There are data to support each possibility but no confirmation of the most important factor.[35]

Another consideration is the misdiagnosis of asthma in the presence of obesity. Symptoms of shortness of breath, exercise-induced dyspnea, and chest tightness as a result of obesity may be misattributed to asthma, resulting in an incorrect diagnosis. Other publications demonstrate that misdiagnosis is as common, up to 30%, in normal weight as in obese individuals, refuting the greater likelihood of misdiagnosis of asthma in obese individuals.[36,37,38]

Diagnostic and Therapeutic Considerations

The therapy of asthma is not modified specifically by increased weight but ideal outcomes are dependent on losing weight. The most effective therapy for asthma, inhaled corticosteroids, may be less effective in the obese individual.[34] This observation does not warrant a modification of the treatment strategy but may prompt the consideration of adding noncorticosteroid therapies to the obese asthmatic. Facilitating weight loss is an ideal but the reality is that most affected individuals cannot lose weight, and if they do so, they usually regain it. Nevertheless, the clinician should encourage weight reduction strategies or consider surgical approaches.[39,40]

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