Obesity May Increase Asthma Incidence

A meta-analysis of 7 studies which included a total 300,000 patients found that being overweight (BMI higher than 25) was associated with an increased incidence of asthma. The incidence of asthma was especially high in obese individuals (BMI higher than 30), with an odds ratio of 1.92.

In this study, there seemed to be a "dose-dependent" increase in the odds of asthma according to weight. One important question is whether those patients had asthma or exertion-related dyspnea related to obesity. Several studies have shown improvement in respiratory symptoms (mainly shortness of breath) when obese patients with asthma loose weight.

References:

Overweight, Obesity, and Incident Asthma. A Meta-analysis of Prospective Epidemiologic Studies. David A. Beuther and E. Rand Sutherland. American Journal of Respiratory and Critical Care Medicine Vol 175. pp. 661-666, (2007).
Obesity and Asthma: Pulmonary Perspective. David A. Beuther, Scott T. Weiss and E. Rand Sutherland. American Journal of Respiratory and Critical Care Medicine Vol 174. pp. 112-119, (2006).
Decreased response to inhaled steroids in overweight and obese asthmatic children. JACI, 2011.
Childhood obesity is associated with an increased risk of worse asthma control and exacerbations. JACI, 2011.
Higher body mass index may decrease response to inhaled corticosteroids in persistent asthma (http://goo.gl/Xt6eP).
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