An elevated body mass index increases lung volume but reduces airflow in Italian schoolchildren

Asthma and obesity are important and growing health issues worldwide. Obesity is considered a risk factor for asthma, due to the induction of changes in airway mechanics and altered airway inflammation.

We cross-sectionally investigated the effect of increased weight on pulmonary function in a large population sample of healthy children, aged 10-17 yrs living in Palermo, Italy. Explanatory effect of weight on lung function variables were evaluated by multiple linear regression models, taking into account height, gender, and age-class.

Among the 2,393 subjects, FVC and FEV1 were positively correlated to weight. Multiple regression models showed that the weight beta coefficient for FEV1 was significantly lower with respect to that for FVC (0.005 and 0.009 l/kg, respectively), indicating a different magnitude in explanatory effect of weight on FVC and FEV1. Both FEV1/FVC and FEF25-75%/FVC ratios were negatively correlated to weight, while FEF25-75% was not significantly correlated. Similar results were obtained also when 807 symptomatic subjects were introduced in the model through a sensitivity analysis.

In healthy children, the disproportionate increase of FEV1 and FVC with weight produces airflow decrease and consequently apparent poorer lung function independently from respiratory disease status.