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 (-0.14 standard deviation scores to -15.9% 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 (FEV₁, 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 post-intervention 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. Primary Source of Funding: U.S. National Institutes of Health (NIH).

Keywords: asthma; childhood asthma; obese asthma; obesity; weight loss.

Figure 1.

Study selection overview: flow diagram of study selection. Adapted by permission from the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) statement (21). RCTs = randomized controlled clinical trials.