An Unrecognized Relationship Between Asthma and Obesity
SOURCE: Pakhale S, et al. Effects of weight loss on airway responsiveness in obese adults with asthma: Does weight loss lead to reversibility of asthma? Chest 2015;147:1582-1590.
The prevalence of asthma is increasing, although the reasons behind this are not entirely clear. There may be an important link between asthma and obesity.
For instance, incident asthma is almost 50% more common in obese persons. Each increment of three units in body mass index (BMI) is associated with a 35% increase in asthma. Even the degree of airway hyperreactivity — the hallmark of asthma — is directly related: For each one-unit increase in BMI (e.g., a BMI change from 30 to 31 kg/m2), there is a 3% increase in airway hyperreactivity.
Whether treatment of obesity might benefit patients with asthma has received little attention in the literature. Pakhale et al performed a prospective controlled trial in obese adults (mean BMI = 45 kg/m2) with asthma to compare metrics of pulmonary function and airway hyperreactivity in subjects who participated in a weight loss program vs control. The intervention group received lifestyle intervention to enhance dietary weight loss and exercise.
The metric for airway hyperreactivity was the PC20 — the amount of methacholine necessary to produce a bronchoconstrictive effect enough to reduce FEV1 by 20% (the more methacholine it takes, the less hyperreactive your airways are).
At the end of the 3-month trial, the intervention group had lost a mean of approximately 17 kg, but the control group had a gain of approximately 1 kg. The intervention group enjoyed improvements in pulmonary function (improved FEV1), asthma quality of life, and PC20. Weight reduction may be an overlooked tool for asthma management.
Weight reduction may be an overlooked tool for asthma management.
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