Atopy and pulmonary function among healthy-weight and overweight/obese children with asthma

Epidemiologic studies have found low/absence of atopy in obese asthmatic children, but the association or lack thereof of atopy with disease morbidity, including pulmonary function, in obese asthma is not well understood. We sought to define the association of atopy with pulmonary function in overweight/obese minority children with asthma.

In a retrospective chart review of 200 predominantly minority children evaluated at an academic Pediatric Asthma Center over 5 years, we compared the prevalence of atopy, defined as $$ 1 positive skin prick test or serum-specific immunoglobulin E quantification to environmental allergens, and its association with pulmonary function in overweight/obese (body mass index [BMI] > 85th percentile) (n = 99) to healthy-weight children (BMI, 5th-85th percentile for age) (n = 101).

In a cohort comprised of 47.5% Hispanics and 39.5% African Americans, 81% of overweight/obese and 74% of healthy-weight children were atopic. While atopic healthy-weight children had lower percent-predicted forced expiratory volume in the first second (FEV₁ ) (93 ± 13.6 vs 107% ± 33.2%, P = .03) and lower percent-predicted forced vital capacity (FVC) (93% ± 12.2% vs 104% ± 16.1%, P = .01) as compared to nonatopic children, atopy was not associated with FEV₁ (P = .7) or FVC (P = .17) in overweight/obese children. Adjusting for demographic and clinical variables, atopy was found to be an independent predictor of FEV₁ and FVC in healthy-weight (β = -2.4, P = .07 and β = -1.7, P = .04, respectively) but not in overweight/obese children (β = .6, P = .5 and β = .8, P = .3).

Atopy is associated with lower lung function in healthy-weight asthmatics but not in overweight/obese asthmatics, supporting the role of nonallergic mechanisms in disease burden in pediatric obesity-related asthma.