Pediatric Obesity Not Associated with Adulthood Asthma

As clinicians continue to seek the underpinning influences and causes of asthma, a recent study conducted in Copenhagen sought to determine an association between childhood obesity and asthma.

The longitudinal study by Ann Arbor, MI-based allergists Katherine McCormack, MD, and Harvey Leo, MD, examined whether being overweight during childhood or adolescence impacted key markers of airway pathophysiology—including fractional exhaled nitric oxide (FeNO) and airway hyperresponsiveness—in early adulthood.

Investigators assessed data from a baseline study conducted in 1986, along with follow-up data collected in 2006. Participants born between 1969-1979, drawn from a civil registration list, were invited to participated in the trial at study’s start. Of the 983 subjects chosen, 527 agreed to participate; just 189 participated in the 2006 follow-up.

Both observed physician visits included questionnaires and semi-structured interviews to ensure validated participant case histories. Early childhood asthma and allergy symptoms, including atopic dermatitis and wheezy bronchitis, were assessed in the questionnaires.

Obese patients were defined as having body mass indexes (BMIs) in the 85^th percentile or greater, according to the study. Patients’ maternal/paternal histories of smoking, asthma, and allergy symptoms were included in the analysis, and forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) were assessed at both the initial and follow-up visit.

Bronchial provocation testing was performed with histamine at baseline, and again with methacholine in the follow-up.

Investigators ultimately found no significant impact of pediatric obesity on the risk of adulthood asthma. When compared to participants at an average or normal baseline pediatric weight, the prevalence of airway hyperresponsiveness among participants aged 27-37 years old at follow-up was not significantly associated with the overweight or obesity at ages 7-17 at study’s start.

At baseline, 158 subjects were normal weight, while 26 were overweight or obese. When compared with the average weight group, the subjects who were identified as overweight were significantly younger at cohort entry, but the prevalence of asthma and atopy did not vary between the 2 groups, investigators noted. In the follow-up study, there was no association was found between BMI and levels of AHR or FeNO.

“There was no significant difference in predicted percentage of FEV₁, FVC, and FEV₁/FVC between the 2 groups,” investigators noted. “Subjects who were overweight or obese at baseline had a significantly higher BMI at follow-up.”

While children in Denmark have some of the lowest rates of obesity in Europe, the number of children worldwide who are considered overweight or obese continues to rise, according to the World Health Organization (WHO). According to recent reports, the rate of increase in developed countries have been 30% or more. By their projection, the global count of obese infants and young children will reach 70 million by 2025.

While both asthma and obesity rates continue to elevate among children, results remain inconsistent among longitudinal studies—including this study—that seek to determine the link between BMI and airway hyperresponsiveness.

Reviewers concluded that this particular study focused on a small sample size, thus limiting its scope, and lacked data on confounding factors that may impact the development of airway hyperresponsiveness. As it now stands, additional research is needed to clarify any relationship between BMI and airway hyperresponsiveness.

The study, “Overweight in Childhood and Adolescence: Does It Lead to Airway Hyperresponsiveness in Adulthood?” was published online in Pediatrics.