The trend was true when investigators used body mass index to classify weight, and when measures such as relative body mass index and percentage of body fat were used.
Children with bronchial asthma who are overweight and obese are significantly more likely to have bronchial obstruction compared with children of normal or low body weight, according to a new study.
Investigators, including corresponding author Tatyana I. Eliseeva, MD, DSc, of the Privolzhsky Research Medical University in Russia, wrote that from a scientific standpoint it is believed that all patients with bronchial asthma could successfully control their disease. However, as many as half of patients with the disease do not have their asthma under control, largely due to comorbid conditions such as obesity and being overweight.
Solving the problem is difficult, though, since there is conflicting data regarding how excess weight affects spirometry readings, the authors said. One reason for the conflicting data, they posited, could be the imprecision of using body mass index (BMI) as a stand-in for weight in pediatric patients.
“The same BMI values may correspond to different types of nutritional status in children of different ages and genders,” the authors wrote. “For example, a BMI of 17.0 in a boy of 11 years 1 month with average physical development (143 cm) will correspond to the median, a girl of 5 years 1 month (height 110 cm)—overweight (+1 Z-score [Z]), and a girl of 17 years (height 163 cm)—protein-energy deficiency (–2Z).”
Eliseeva and colleagues decided to supplement BMI by using a relative BMI (RBMI), which uses a ratio of the patient’s BMI to the average BMI for children with the same age and gender.
The investigators recruited 54 patients with bronchial asthma between the ages of 8 to 17 years old. Most of the patients (33) were boys. The patients had a range of nutritional statuses based on BMI Z-scores: 5 had low body weight, 18 had normal body weight, 17 were considered overweight, and 14 were considered obese.
The patients were evaluated using a number of spirogram parameters, including forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio, and maximum expiratory flow at the point of 25% loop flow-volume (MEF 25).
An analysis of the readings showed that as body weight increased, FEV1/FVC ratio and MEF 25 both decreased. Notably, those findings held true not only for BMI, but also when evaluated against other measures of weight, including RBMI and percentage of body fat.
“It is obvious that there may be various pathogenetic mechanisms of the influence of obesity on the physiology of the lungs, including, inter alia, an imbalance of pro- and anti-inflammatory cytokines,” they wrote.
For instance, they said, adipokines have been linked with bronchial inflammation and hyperreactivity.
Yet, they added that it is also possible the reverse is true: that asthma leads to nutritional changes.
“And this is due not only to changes in the level of physical activity in connection with the disease and the reception of exogenous glucocorticoids, but also with the possibility of local synthesis of alpha-melanocyte stimulating hormone, respectively, and its predecessor-adrenocorticotropic hormone,” they wrote.
Overall, the authors said the potential causal links remain a topic of open scientific question. They said deeper research is needed to understand practical issues such as how to diagnose, treat, and effectively control children with bronchial asthma who are obese.
“An increase in BMI, an indirect indicator of obesity, is a predictor of worsening bronchial patency in patients with [bronchial asthma] regardless of the sex of the child,” they concluded.
Khramova RN, Tush EV, Khramov AA, et al. Relationship of nutritional status and spirometric parameters in children with bronchial asthma. Sovrem Tekhnologii Med. 2021;12(3):12-23. doi:10.17691/stm2020.12.3.02