Obese asthmatics have increased risks for poor control and worse outcomes, and may be associated with a less atopic phenotype. We sought to determine the prevalence of obesity in our asthma clinic and determine whether this was connected to total serum IgE level.
After informed consent and IRB approval, 114 subjects were recruited from our asthma clinic from 2011-2015. Participants were stratified by BMI, initially separating the cohort into non-obese (BMI less than 30; n=66) and obese asthmatics (n=48). Subsequently, cohorts were divided into four groups: BMI <25; 25-30; 30-40; >40. T-tests and ANOVAs were use to assess differences between total serum IgE levels among these groups. Additionally, we ran similar tests when stratifying the cohort by sex and FEV1% levels.
Obesity was highly prevalent in our asthma clinic (42% of subjects). The entire cohort had a mean total serum IgE of 569.8 (kU/L) ± 2197.3 (median: 93.9; range 0.5-22,283). Total IgE was 774.9±852.7 in non-obese asthmatics vs 287.8±460.7 in obese subjects, which did not reach statistical significance (p=0.24). Dividing the cohort into four groups across BMI values, a one-way ANOVA did not reveal any significant variance (p=0.51 unadjusted; p=0.65 adjusted for sex). When isolating groups 1 and 4, no significant variance was found (p=0.42). We also performed these tests within the interquartile range of serum IgE values and found similar results.
Our study showed no correlation between total serum IgE levels and BMI in asthmatics regardless of severity of illness. Further studies with other markers of atopy are needed.