Methods: Fifty elderly asthmatics (24 female; 26 male) aged 55 to 83 years (mean: 63.8) were consecutively recruited from a respiratory outpatient clinic. 39/50 were on inhaled steroids. eNO was measured with a NIOX MINO analyzer and specific IgE (sIgE) to inhalant and food allergens measured in blood by fluorescence enzyme immunoassay (Phadia 100). Atopy was defined as any sIgE ≥ 0.35 KU/L. Results are presented as geometric mean levels with 95% confidence intervals (95% CI). Comparisons were by Mann-Whitney U-test with significance set at the p 0.05 level.
Results: Twenty subjects were atopic with 14/20 atopic to house dust mite (HDM). Geometric mean FeNO level (95% CI) for all 50 subjects was 23.1 ppb (95%CI: 18.1-29.3) with no significant differences between females and males. FeNO levels were significantly higher in atopic vs non-atopic subjects (33.4 ppb, 95% CI: 21.2-52.6 vs 18.3, 95% CI: 14.4-23.4; p=0.003). FeNO geometric mean level in HDM-sensitized subjects (n=14) was 38.8 ppb (95% CI: 22.9-65.8) while in non-HDM sensitized atopics (n=6) this was 23.5 ppb (95% CI: 7.4-74.1).
Conclusions: Atopy in elderly asthmatics in Taiwan is associated with significantly higher FeNO levels predominantly driven by sensitization to HDM.