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This Article Full Text (PDF) All Versions of this Article: chest.07-2959v1 134/2/317    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Article Archive Download to citation manager Google Scholar Articles by Lessard, A. Articles by Boulet, L.-P. PubMed PubMed Citation Articles by Lessard, A. Articles by Boulet, L.-P.

Obesity and Asthma: A Specific Phenotype?

From : Centre de Recherche, Hôpital Laval, Institut de cardiologie et de pneumologie de l'Université Laval

lpboulet{at}med.ulaval.ca

Abstract

BackgroundObesity is associated with an increased prevalence of asthma, especially in women, and appears to be more severe in the obese. This study aimed to determine if obese subjects have a specific asthma phenotype.

MethodsForty-four consecutive obese (body mass index [BMI] 30 kg/m²) subjects and 44 consecutive non-obese (BMI < 25 kg/m²) subjects, all with asthma, had an asthma control questionnaire, a methacholine challenge with symptom perception scores and sputum induction for differential cell count. Their BMI, waist circumference and waist-to-hip ratio also were measured.

ResultsDespite similar expiratory flows, bronchodilator response, airway responsiveness to methacholine and symptom perception scores, asthma control was poorer in obese than in non-obese subjects (p = 0.005). Total lung capacity (p = 0.01), expiratory reserve volume (p < 0.0001), functional residual capacity (p < 0.0001) and residual volume (p = 0.006) were lower in obese than in non-obese subjects. Induced sputum eosinophil and neutrophil counts were similar in both groups although there was an inverse correlation between sputum eosinophils and waist circumference and a trend for a similar relationship for BMI. Blood serum C-reactive protein (p = 0.009) and fibrinogen (p = 0.0004) levels were higher in obese than in non-obese subjects.

ConclusionObese people with asthma had poorer asthma control than non-obese asthmatics despite similar symptoms perception. Bronchial and systemic inflammatory characteristics and the specific pattern of pulmonary function changes suggest a different phenotype of asthma in these subjects.

Key Words: Asthma • asthma control • BMI • lung function • obesity • sputum induction • symptom perception • inflammatory markers