Obesity a Major Preventable Risk Factor for Asthma in Children

Obesity has been linked to new asthma cases in adults, but the risk of asthma in children remains a subject of debate. Now, a new study in Pediatrics concludes that 23%-27% of new asthma cases in children with obesity is directly attributable to obesity, and without overweight and obesity as a factor there would be 10% fewer cases of pediatric asthma in the United States.

Using PEDSnet (pedsnet.org), a national pediatric network that pools and standardizes electronic health record (EHR) data, the researchers examined the obesity-asthma relationship in children in a longitudinal study comparing the risk of asthma among children with normal weight and those with obesity. Clinical data were obtained from 6 PEDSnet institutions across 22 states, including all clinical settings—primary care, hospital, emergency, ambulatory, and subspecialty care as well as laboratory and imaging settings—between January 2009 and December 2015.

Participants were 2 to 17 years of age; children with any documented diagnosis of cystic fibrosis, ciliary dyskinesia, childhood cancer, inflammatory bowel disease, or bronchopulmonary dysplasia were excluded from the study. Each individual case of overweight or obesity was matched with children of a healthy weight in a 1:1 ratio. The 3 study groups were defined as follows:

• Overweight (Body Mass Index [BMI] in the 85th-94th percentile adjusted for sex and age)
• Obese (BMI in the ≥95th percentile adjusted for sex and age)
• Matched comparators whose BMI percentile ranged between the 25th and 64th percentile adjusted for sex and age

None of the participants had previous documentation of asthma at the study’s baseline. Rates of incident asthma were compared over time for each group, with additional confirmation of asthma diagnosis with spirometry.

A total of 507,496 children met inclusion criteria for study entry; 41,330 (8.14%) and 27,461 (5.41%) were diagnosed with asthma by a pediatric healthcare provider in at least 1 and 2 provider encounters, respectively. The overall incidence rate for new asthma cases in the population was 2.7 per 1000 patient years, ranging from 2.4 per 1000 patient years among children with normal weight to 3.2 per 1000 patient years among children with obesity. Both overweight and obesity were associated with an increased risk for new asthma diagnoses.

Being male, African American, having Medicaid or no insurance, and a younger age were all associated with a higher asthma incidence. Baseline presence of allergic rhinitis, food allergy, anaphylaxis, and past use of various medications (any proton pump inhibitor or histamine-2 blocker), were significantly associated with a higher risk for incident asthma.

“Our study provides a novel understanding for the extent to which childhood obesity worsens the pediatric asthma epidemic in the United States,” the researchers conclude. Roughly 18% of US children are obese. Childhood obesity alone can increase the rate of new asthma diagnoses by more than 6 cases per 1000 patient years, the authors write. Their data suggest that avoiding obesity would reduce the risk for new onset of asthma in children by 26% to 38%.

If current estimates of US pediatric asthma prevalence (6-8 million cases) are correct, the study’s authors say their findings suggest that up to 12.7% (up to 1 million) cases of childhood asthma are directly attributable to overweight and obesity. “Currently, there are few known preventable factors that can be used to reduce childhood asthma,” the researchers note. Their data suggest that reducing the onset of obesity in childhood may significantly reduce the public health burden of asthma. “Furthermore, because we and others have shown that obesity among children with asthma appears to increase disease severity, the findings of the current report are particularly compelling.”

Reference

Lang JE, Bunnell HT, Hossain MJ, et al. Being overweight or obese and the development of asthma. Pediatrics. 2018;142(6):e20182119. doi: 10.1542/peds.2018-2119.