Although obesity has been hypothesized to worsen asthma, data from studies of subjects with well-characterized asthma are lacking.Objective:
We sought to evaluate the relationship between body mass index (BMI), asthma impairment, and response to therapy.Methods:
BMI (in kilograms per meter squared) and asthma phenotypic and treatment response data were extracted from Asthma Clinical Research Network studies. The cross-sectional relationship between BMI and asthma impairment was analyzed, as was the longitudinal relationship between BMI and response to asthma controller therapies.Results:
One thousand two hundred sixty-five subjects with mild-to-moderate persistent asthma were evaluated. Analyses of lean versus overweight/obese asthmatic subjects demonstrated small differences in FEV1 (3.05 vs 2.91 L,P= .001), FEV1/forced vital capacity ratio (mean, 83.5% vs 82.4%;P= .01), rescue albuterol use (1.1 vs 1.2 puffs per day,P= .03), and asthma-related quality of life (5.77 vs 5.59,P= .0004). Overweight/obese asthmatic subjects demonstrated a smaller improvement in exhaled nitric oxide levels with inhaled corticosteroid (ICS) treatment than did lean asthmatic subjects (3.6 vs 6.5 ppb,P= .04). With ICS/long-acting β-agonist treatment, overweight/obese asthmatic subjects demonstrated smaller improvements in lung function than lean asthmatic subjects, with an 80 mL (P= .04) and 1.7% (P= .02) lesser improvement in FEV1 and FEV1/forced vital capacity ratio, respectively. Significant differences in therapeutic response to leukotriene modifiers between BMI categories were not observed.Conclusions:
Increased BMI is not associated with clinically significant worsening of impairment in subjects with mild-to-moderate persistent asthma. There is a modest association between increased BMI and reduced therapeutic effect of ICS-containing regimens in this patient population. Prospective studies evaluating the effect of being overweight or obese on treatment response in asthma are warranted.