Dyspnea in overweight children: Is it asthma?

Abstract

In a Dutch birth cohort study published in this issue of the Journal, children had an increased risk of bronchial hyperresponsiveness or dyspnea at age 8 years if they had a high body mass index (BMI) at 6 to 7 years of age with or without increased BMI at an earlier age. Taking advantage of the longitudinal nature of their study of 3,756 children, the authors also report the encouraging finding that children who had a high BMI at a young age but whose BMI returned to normal did not have increased risk either of bronchial hyperresponsiveness or dyspnea. As always, extrapolation from an observational study to early-life interventions should be done cautiously. It is not known whether children whose BMI decreases without any known deliberate intervention are the subset of children who might benefit from BMI screening or from weight-reduction programs. Programs for screening and early intervention in obesity abound, but further prospective evaluation of their success in reducing weight and obesity-associated respiratory symptoms is needed. But what does overweight-associated dyspnea signify in the children from this birth cohort, and is dyspnea a symptom of asthma, as the investigators suggest? Mouse model data suggest that obesity can lead to bronchial hyperresponsiveness. Airway narrowing can occur through obesity-associated lung and tidal volume reduction, low-grade systemic inflammation, or obesity-related changes in adipose-derived hormones, including leptin and adiponectin. Nevertheless, studies of adults in which data suggest that asthma might be overdiagnosed in obese adults with dyspnea are accumulating. Misdiagnosis of asthma can result in inappropriate prescription of short-acting bronchodilators or corticosteroids in persons who are short of breath for obesity-related dyspnea that does not represent reversible airway obstruction. In a study of 16,171 participants ( 17 years of age) from the Third National Health and Nutrition Examination Survey, the highest BMI quintile (ie, the most obese participants) was associated with the greatest risk of self-reported asthma, bronchodilator use, and dyspnea with exertion (odds ratio, 2.66; 95% CI, 2.35-3.00). The highest BMI quintile, however, had the lowest risk for significant airflow