One Quarter of New Pediatric Asthma Cases Tied to Obesity

Marcia Frellick

November 26, 2018

An estimated 23% to 27% of new asthma cases in children are directly caused by obesity, new research indicates.

"In the absence of overweight and obesity, 10% of all US cases of pediatric asthma could be avoided," write Jason E. Lang, MD, MPH, of the Divisions of Allergy and Immunology and Pulmonary Medicine at Duke University School of Medicine and Duke Children's Hospital and Health Center in Durham, North Carolina, and colleagues.

The findings were published online today in Pediatrics

Obesity has previously been linked with new asthma cases in adults, and researchers estimate obesity causes approximately 250,000 new adult cases per year. The current study is the first to measure the incidence and risk across a large, diverse national pediatric population.

Lang and colleagues used the PEDSnet clinical data research network to compare asthma incidence among overweight and/or obese children with that in healthy-weight children aged 2 to 17 years. They analyzed data from 507,496 children and 19,581,972 encounters that occurred between January 2009 and December 2015. The researchers matched individual children classified as overweight or obese in a 1:1 ratio with children whose weight was in a healthy range. Children were also matched for demographic characteristics and insurance status. The average observation period was 4 years.

Incidence was defined as at least two encounters with a diagnosis of asthma and at least one asthma controller prescription.

Overall, the adjusted risk for incident asthma was higher among overweight children (relative risk [RR], 1.17; 95% confidence interval [CI], 1.10 - 1.25) and obese children (RR, 1.26; 95% CI, 1.18 - 1.34). The adjusted risk for spirometry-confirmed asthma was also higher among obese children (RR, 1.29; 95% CI, 1.16 - 1.42).

Few Preventive Measures for Asthma

The findings are important because there are few preventive measures to reduce childhood asthma, the authors note.

These data suggest reducing obesity in children "would significantly reduce the public health burden," they write.

In an accompanying editorial , Deepa Rastogi, MBBS, MS, from Children's Hospital at Montefiore, Albert Einstein College of Medicine in the Bronx, New York, says the numbers show another reason these findings are so important. She explains that pediatric asthma prevalence has stayed at about 10% for many years despite advances in early diagnosis, management, and mitigation of environmental factors.  At the same time, obesity rates are at nearly 20% and rising among some groups, and these new data show how that could boost pediatric asthma rates.

"[W]e are looking at an ∼5% increase in childhood asthma due to obesity, suggesting that over time obesity-induced asthma will become a major type of childhood asthma," she said.

Rastogi notes a strength of the study is that the database, PEDSnet, includes data from eight major American pediatric health systems, allowing for a broad look at races, ethnicities, and various definitions of asthma.

The matching of children for demographic traits and insurance status separated the possible confounding of those variables, she notes.

Given the findings, Rastogi suggests that clinicians measure waist circumference and quantify metabolic abnormalities in evaluating pediatric patients with obesity to better identify those at risk of developing pulmonary complications.

"Because normative values exist for waist circumference and for the classification of metabolic abnormalities in children, those with evidence of [one or more] of these obesity related complications should be the ones actively screened for asthma," she writes.

Further research, she says, should investigate why some obese children develop asthma and some do not, and should differentiate children who become obese as a result of asthma from those who develop asthma as a result of obesity. This knowledge, Rastogi said, will aid in the development of novel targeted therapies.

Children 2 to 17 years old were eligible for inclusion in the study if they had an age- and sex-adjusted body mass index in at least the 85th percentile and no recorded diagnosis of asthma or wheezing at or before the initial visit in the study period.

The study excluded children using asthma medications without a formal diagnosis and those diagnosed with asthma within 18 months of the initial visit. Children were also excluded if they had documented cystic fibrosis, ciliary dyskinesia, childhood cancer, inflammatory bowel disease, or bronchopulmonary dysplasia.

The study was funded by the Patient-Centered Outcomes Research Institute and by institutional development funds from Nemours Children's Hospital and Nemours Children's Health System.

One author reports serving on advisory boards for Merck, Sanofi Pasteur, and Pfizer, and working as a consultant for Pfizer, but does not receive funding from these entities.

The other study authors and Rastogi have disclosed no relevant financial relationships.

Pediatrics.  Published online November 26, 2018. Full text, Editorial

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