Decreased response to inhaled steroids in overweight and obese asthmatic children

Abstract

Background: The mechanisms and consequences of the observed association between obesity and childhood asthma are unclear.

Objectives: We sought to determine the effect of obesity on treatment responses to inhaled corticosteroids in asthmatic children.

Methods: We performed a post hoc analysis to evaluate the interaction between body mass index (BMI) and treatment with inhaled budesonide on lung function in the Childhood Asthma Management Program trial. Participants were then stratified into overweight/obese and nonoverweight groups, and their response to inhaled budesonide was analyzed longitudinally over the 4 years of the trial.

Results: There was a significant interaction between BMI and budesonide for prebronchodilator FEV(1)/forced vital capacity (FVC) ratio (P = .0007) and bronchodilator response (BDR; P = .049) and a nonsignificant trend for an interaction between BMI and budesonide on prebronchodilator FEV(1) (P = .15). Nonoverweight children showed significant improvement with inhaled budesonide in lung function (FEV(1), FEV(1)/FVC ratio, and BDR) during the early (years 1-2) and late (years 3-4) stages of the trial. Overweight/obese children had improved FEV(1) and BDR during the early but not the late stage of the trial and showed no improvement in FEV(1)/FVC ratio. When comparing time points at which both groups showed a significant response, the degree of improvement among nonoverweight children was significantly greater than in overweight/obese children at most visits. Nonoverweight children had a 44% reduction in the risk of emergency department visits or hospitalizations throughout the trial (P = .001); there was no reduction in risk among overweight/obese children (P = .97).

Conclusions: Compared with children of normal weight, overweight/obese children in the Childhood Asthma Management Program showed a decreased response to inhaled budesonide on measures of lung function and emergency department visits/hospitalizations for asthma.

Figure 1. Effect of budesonide on measures of lung function and bronchodilator response by BMI group

A. Pre FEV₁ (% of predicted); B. Pre FEV₁FVC; C. BDR. Budesonide in blue/diamonds; placebo/nedocromil in red/squares. Solid lines indicate time points where difference between treatment arms was significant; non-significant visits in dotted lines. Stars show points where there was a significant difference between arms and from baseline. Arrows and p-values are for overall longitudinal effect of budesonide over months 0–20 or 24–48, compared to baseline.

Figure 2. Effect of budesonide on asthma-related outcomes, by overweight status

Lines represent the difference between treatment arms (budesonide – placebo/nedocromil; negative numbers indicate an improvement in the budesonide arm compared to the non-budesonide arm). Overweight/obese group in orange/circles; non-overweight in green/triangles. A: Average number of prednisone courses per patient since the previous visit. B: Percentage of children reporting any urgent care visits or hospital admissions. Note: Solid lines/symbols represent visits where difference was significant; non-significant time points in dotted lines.