Weight Loss for Children and Adults with Obesity and Asthma. A Systematic Review of Randomized Controlled Trials

Abstract

Background: Asthma and obesity are major public health problems, affecting hundreds of millions of people worldwide. Obesity is associated with increased asthma risk and severity, and lower asthma-related quality of life. Objective: In this systematic review, we aimed to evaluate whether weight loss in subjects with obesity and asthma leads to improvement in asthma-related outcomes. Data Sources and Extraction: We searched PubMed and Google Scholar for all studies in English published January 2000-December 2018. Studies were included if they were randomized, controlled clinical trials (RCTs) for overweight/obese children or adults with asthma, with sufficient data to assess outcomes and study quality. Non-randomized and non-controlled studies were excluded, as well as those in subjects without overweight/obesity, or with non-asthmatic controls. Synthesis: We identified four RCTs involving children (total n = 246) and six involving adults (n = 502). All interventions were designed for weight loss and varied from dietary restrictions to multifactorial interventions with exercise training and cognitive behavioral therapy; the duration of intervention ranged from 8 weeks to 18 months. All RCTs reported successful improvements in weight or body mass index (20.14 standard deviation scores to 215.9% BMI reduction in children, 1.8%-14.5% weight loss in adults). RCTs generally reported improvements in asthma-related quality of life and, to some degree, asthma control. RCTs involving adults also reported improvements in lung function (FEV 1 , FVC, TLC), while RCTs in children showed less consistent results. Conclusions: These findings suggest that weight loss in subjects with obesity and asthma may improve asthma outcomes. However, there was wide variability in populations studied, baseline and postintervention assessments, follow-up length, outcome definition and reporting, and statistical approaches, which hindered the ability to compare studies, perform a pooled analysis, or assess generalizability.

Bariatric surgery: a potential cure for asthma?

“…The pathophysiology of the asthma-obesity link is complex and involves mechanical [6], cytokine-mediated [6,7] and genetic factors [6,8], with complex genetic-environmental interactions [6]. Furthermore, weight-loss interventions have shown improvement in asthma outcomes [9][10][11]. In a recent meta-analysis of randomised clinical trials (RCTs) of weight-loss interventions, OKONIEWSKI et al [11] reviewed four RCTs in children and six in adults of weight-loss interventions in obese asthmatics and concluded that, while the available studies are not uniform, weight loss leads to improvement in asthma-related quality of life, asthma control and lung function.…”

Pediatric obesity‐related asthma: A prototype of pediatric severe non‐T2 asthma

“…One of the approaches to manage obesity-related asthma is to address body weight. Some weight-loss studies conducted in children, 88 but not all, 23 have shown an improvement in asthma disease burden, including improvement in pulmonary function, although there was no change in systemic inflammation. 88 These findings differed from pre and post studies on adult bariatric surgery patients where in addition to improvement in airway responsiveness 89 and lung volumes, 90 there was an improvement in systemic inflammatory measures which correlated with improvement in pulmonary function, supporting a role of systemic immune responses in the obese asthma phenotype.…”

“…Cumulative weight gain over time is associated with asthma‐like symptoms, such as wheeze . Therefore, weight loss is associated with smaller and less consistent improvements in asthma outcomes in children relative to adults . Ethnic differences may stem from differences in body fat distribution, particularly in light of the contribution of truncal adiposity to the obese‐asthma link .…”

“…88 These findings differed from pre and post studies on adult bariatric surgery patients where in addition to improvement in airway responsiveness 89 and lung volumes, 90 there was an improvement in systemic inflammatory measures which correlated with improvement in pulmonary function, supporting a role of systemic immune responses in the obese asthma phenotype. [89][90][91] In light of conflicting data between adults and children, 23 there remains a need for mechanistic studies to elucidate the impact of differences in extent, timing, and modality of weight loss/weight control during different stages of life, to decrease in disease burden in obesity-related asthma.…”

“…21,22 Therefore, weight loss is associated with smaller and less consistent improvements in asthma outcomes in children relative to adults. 23 Ethnic differences may stem from differences in body fat distribution, particularly in light of the contribution of truncal adiposity to the obese-asthma link. 24,25 The cross-sectional nature of the studies may further limit their inferences, due to lack of detail on the chronology of obesity onset relative to that of asthma.…”