Pulmonary function, exhaled nitric oxide and symptoms in asthma patients with obesity: a cross-sectional study

Abstract

BackgroundObesity is a risk factor for the development of asthma. In patients with obesity the diagnosis of asthma is often based on symptoms, but without objective measurements. Nevertheless, obesity-associated asthma is recognized as a distinct asthma phenotype. Therefore, this study explores lung function and symptoms in asthma patients with and without obesity.MethodsThe Netherlands Epidemiology of Obesity (NEO) study is a population-based cohort study with 6671 participants (aged 45–65 years) of whom 472 had asthma. Of this latter group, linear regression analysis was used to examine differences in lung function and symptoms between asthma patients with (n = 248) and without obesity (n = 224), and between asthma patients with and without increased FeNO. Analyses were adjusted for confounders.ResultsAsthma patients with obesity had lower predicted FEV1 and FVC values than patients without obesity [adjusted mean difference (MD) -3.3% predicted, 95% CI -6.5, −0.2; adjusted MD −5.0% predicted, 95% CI -7.8, −2.1]. The prevalence of symptoms was higher in patients with obesity. Asthma patients with obesity and with increased FeNO had lower FEV1 and FEV1/FVC values compared with those with low FeNO (adjusted MD −6.9% predicted, 95% CI -11.7, −2.0; −2.4%, 95% CI -4.6, −0.2).ConclusionAsthma patients with obesity had lower FEV1 and FVC values than patients without obesity. This suggests that patients with obesity have restrictive lung function changes, rather than obstructive changes. Asthma patients with obesity and increased FeNO showed more obstructive changes. FeNO might help to identify patients with eosinophilic inflammation-driven asthma, whereas patients with low FeNO might have an obesity-associated asthma phenotype in which symptoms are partly caused by the obesity.Electronic supplementary materialThe online version of this article (10.1186/s12931-017-0684-9) contains supplementary material, which is available to authorized users.

Obesity and Asthma: Key Clinical Questions

“…Thus, in the prospective Netherlands Epidemiology of Obesity cohort study, high FeNO levels were observed in 25% of obese asthmatics. When compared with the remaining obese asthmatics, those with high FeNO levels had greater bronchoconstriction and more symptoms related to pollen, dust, or animal exposure, suggesting the predominance of a T H 2 pattern [35].…”

“…In addition, we must confirm that the patient's symptoms are related to the objective presence of reversible airflow limitation, together with changes in lung volumes and bronchial hyperresponsiveness [43,47]. Obesity itself does not alter the bronchial response to methacholine in terms of FEV 1 values [24,35], thus making the methacholine challenge test especially useful in the diagnosis of asthma. However, during bronchoconstriction, obese patients without asthma develop more dyspnea [37,48,49] and air trapping than nonobese patients [50], probably as a result of greater limitation of expiratory flow and premature closure of the airways.…”

“…Several important considerations must be taken into account when diagnosing asthma in an obese patient. First, obese patients commonly have symptoms that simulate asthma [35]. The low-intensity systemic inflammation associated with obesity (neuroinflammation) is likely responsible for the greater proprioceptive sensitivity of obese patients.…”

Metabolic aspects of the relationship of asthma and obesity

“…Лица, страдающие БА на фоне ожирения, испытывают на себе влияние феномена полиморбидности, что в сочетании с развитием резистентности к ингаляционным глюкокортикостероидам сопровождается ухудшением контроля течения основного заболевания, повышением частоты и длительности госпитализации [15]. Пациенты с БА, сочетанной с ожирением, имеют больше респираторных симптомов и более низкие значения объема форсированного выдоха за первую секунду (ОФВ1) и форсированной жизненной емкости легких (ФЖЕЛ) по сравнению с пациентами без ожирения [16]. Ассоциация БА и ожирения имеет гендерные и возрастзависимые особенности [17].…”

“…В то же время в исследовании M.J. Kasteleyn и соавт. не было обнаружено различий в уровне выдыхаемого NO между пациентами с БА без ожирения и пациентами, страдающими БА на фоне ожи-рения [16]. Продуцируемый NO, наряду с защитным эффектом (расслабление гладких мышц бронхов, ослабление гиперчувствительности дыхательных путей), может оказывать цитотоксическое или цитостатическое действие на клетку при определенных условиях.…”