Does body mass index influence responsiveness to inhaled corticosteroids in persistent asthma?

Background: Although the relationship between asthma and obesity has been extensively explored, the effect of body mass index (BMI) on the dose-response relationship to inhaled corticosteroids (ICS) has received little attention.

Objective: To assess the dose-response of inhaled budesonide on outcome measures of asthma between overweight and normal weight patients with persistent asthma.

Methods: Seventy-two patients with mild to moderate persistent asthma from a post hoc analysis of previously reported trial data were divided into 2 groups: overweight, BMI 25 kg/m(2) or higher; normal weight, BMI less than 25 kg/m(2). Each group received 4 weeks' treatment with inhaled (hydrofluoroalkane) budesonide 200 μg/day then 800 μg/day with ICS washout pretreatment. Outcome measures forced expiratory volume in 1 second (FEV(1)), fractional exhaled nitric oxide (FeNO), methacholine PC20, total daily asthma symptom score, and overnight urinary cortisol/creatinine ratio were performed at baseline and after each dose.

Results: Significantly greater improvements were seen in the normal weight group for both FeNO and symptom responses at 0 to 200 μg and 0 to 800 μg ICS doses (as change from baseline), compared with the overweight group: FeNO 0 to 200 μg, P = .002; 0 to 800 μg, P = .045; symptoms 0 to 200 μg, P = .002; 0 to 800 μg, P = .013. A trend also was seen toward attenuated cortisol suppression in overweight subjects at 0 to 800 μg (P = .06), but no significant difference was seen at either dose in FEV(1) and methacholine PC20 between weight groups.

Conclusion: Overweight patients with persistent asthma may have attenuated symptom and FeNO dose responses to inhaled budesonide compared with normal weight patients with asthma, with no differences in FEV(1) or methacholine PC20 between groups. Attenuated cortisol suppression in the overweight group may be the clue to this difference, alluding to reduced peripheral lung deposition or absorption in overweight patients with asthma.