PURPOSE OF THE STUDY.
The goal of this study was to assess if dietary intervention (DI) can achieve weight loss in obese asthmatic children and if diet-induced weight loss leads to changes in asthma outcomes.
The study evaluated 32 obese (BMI z score ≥1.64 SD score) Australian children aged 8 to 17 years, with a physician diagnosis of asthma. Exclusion criteria included unexplained weight change during the past 3 months, inflammatory or endocrine disorders, and respiratory disorders other than asthma.
In this 10-week, randomized controlled trial, 32 obese asthmatic children were randomized to a wait-list control (WLC) group (n = 16) or a DI group (n = 16). DI participants had a targeted 500-kcal/d reduction from individually calculated age- and gender-appropriate energy requirements and either attended dietitian counseling sessions or were contacted by telephone weekly. Asthma status, quality of life, tobacco exposure, dynamic and static lung function, and plethysmography were assessed at baseline and postintervention.
BMI z score was significantly reduced in the DI group versus the WLC group. Expiratory reserve volume (ERV) increased significantly within the DI group compared with baseline; however, the ERV difference between the 2 groups was not statistically significant. The Asthma Control Questionnaire score improved significantly within the DI group compared with the WLC group. There was no change in the number or proportion of eosinophils or neutrophils within or between groups. There was a nonsignificant trend toward reduction in percentage of neutrophils in the DI group. C-reactive protein (CRP) increased significantly in the WLC group compared with the DI group. No change was observed in IL-6, leptin, or adiponectin levels within or between groups. Change in BMI z score correlated with change in CRP and change in exhaled nitric oxide. Change in the Asthma Control Questionnaire was associated with change in CRP.
DI can induce acute weight loss in obese asthmatic children, with improvements in static lung function, asthma control, and self-reported quality of life. DI was effective in reducing BMI z score by a statistically significant 0.2 BMI SD score, which is comparable to previous studies. Systemic and airway inflammation did not change after weight loss.
This is a novel pilot study. Previous studies of weight-loss interventions in asthmatic patients have primarily been in adults, and the majority have investigated surgically induced weight loss. Limitations to the present study include small sample size, uneven randomization, and self-report of several measures. Despite these acknowledged limitations, the findings suggest that DI can improve multiple asthma outcomes. Given the high prevalence of obesity in the asthmatic pediatric population, additional and larger trials are warranted. Areas for future study include additional outcome measures such as use of rescue medications, asthma-related hospitalizations, and potential adverse effects.
- Copyright © 2014 by the American Academy of Pediatrics