Obesity proved to be a major risk factor for increased asthma symptom days in asthmatic preschoolers who were not using inhaled corticosteroids, researchers reported.
Compared with normal-weight preschoolers not receiving treatment with a corticosteroid inhaler, untreated overweight children suffered 37 additional symptom days per year. That amounted to 5 extra weeks of symptoms compared with their healthy-weight, asthmatic peers, according to Jason E. Lang, MD, MPH, of Duke Children’s Hospital and Health Center in Durham, North Carolina, and colleagues.
However, the post hoc analysis also showed that daily inhaler use was highly effective for controlling symptoms in overweight kids, they wrote in the Journal of Clinical Immunology.
“Untreated toddlers who were overweight or obese had 70% more asthma symptom days, and their risk for asthma exacerbations was about 75% higher than untreated, normal-weight toddlers,” Lang told MedPage Today. “But on treatment, this obesity-related effect was not seen.”
Lang said the combined analysis of three National Heart, Lung and Blood Institute (NHLBI)-funded studies is among the first to examine the impact of obesity on asthma symptoms and treatment response in very young children.
Obesity has been shown to be associated with poorer treatment response in adults, adolescents and even older children with asthma, but this did not appear to be the case among the very young children in the analysis.
While the researchers did not study the reasons for this, Lang speculated that the better treatment response in overweight and obese toddlers could be because they have not yet been exposed to the prolonged inflammation that causes the lungs to be less responsive.
The post hoc study included data from three previously reported, large, multi-center trials that included children, ages 2-5 years (INFANT, PEAK, and MIST trials). Using combined data from the three trials, the researchers compared annualized asthma symptom days and exacerbations among normal weight (BMI 10-84th percentile) and overweight/obese (BMI ≥85th percentile) kids.
Participants had been randomized to receive daily inhaled corticosteroid (ICS), intermittent corticosteroid, or daily placebo. Simple and multivariate linear regression was used to compare BMI-groups.
The analysis revealed that
among the children not on inhaled corticosteroid therapy, overweight children had more asthma symptom days (90.7 versus 53.2, P=0.020) and exacerbations (1.4 versus 0.8, P=0.009), compared with normal-weight children.
Within the ICS-treated groups, overweight and normal weight children had similar asthma symptom days:
- Daily ICS: 47.2 versus 44.0 days (P=0.44)
- Short-term ICS: 61.8 versus 52.9 days (P=0.46)
- As-needed ICS: 53.3 versus 47.3 days (P=0.53)
Overweight and normal weight ICS-treated children also had similar exacerbations:
- Daily ICS: 0.6 versus 0.8 (P=0.10)
- Short-term ICS: 1.1 versus 0.8 days (P=0.25)
- As-needed ICS: 1.0 versus 1.1 (P=0.72)
Compared with placebo, daily ICS in overweight children led to fewer annualized asthma symptom days (90.7 versus 41.2, P=0.004) and exacerbations (1.4 versus 0.6, P=0.006).
“This is the first study to our knowledge to examine the effect of high BMI on asthma severity and ICS response in preschool age children,” the researchers wrote. “Strengths of the current study include that it involved a large number of preschoolers from three highly controlled trials with documented drug adherence and extensive phenotyping.”
The three trials also had similar inclusion/exclusion criteria, which allowed for the consolidation of individual patient-level data.
Study limitations included its post hoc nature and the lack of power to analyze effects specifically related to being overweight.
“It is possible that other factors, such as early growth patterns and nutrition could be involved here,” Lang said. “Hopefully, we can continue to do research in this early age group to look at growth patterns and diet. I think these things may help explain asthma characteristics in later childhood.”
The INFANT, PEAK, and MIST trials were funded by the National Heart, Lung and Blood Institute (NHLBI) AsthmaNet.
Lang disclosed no relevant relationships with industry. One co-author disclosed a relevant relationship with NHLBI AsthmaNet.
Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner