BACKGROUND: Exhaled nitric oxide (FeNO) has a potential clinical role in asthma management. Constitutive factors such as age, height and male gender, as well as individual characteristics, as IgE sensitisation and smoking, affect levels of FeNO in population-based studies. However their effect on FeNO in subjects with asthma has been scarcely studied.
OBJECTIVE: To study the effects on FeNO of these commonly regarded determinants, as demonstrated in healthy subjects, as well as menarche age and parental smoking, in a population of asthmatics.
MATERIAL AND METHODS: FeNO was measured in 557 subjects with asthma from the Swedish GA2LEN study. Allergic sensitisation was assessed by skin prick tests to most common aeroallergens. Upper airway comorbidities, smoking habits, smoking exposure during childhood, hormonal status (for women) were questionnaire-assessed.
RESULTS: Male gender (p<0.001), greater height (p<0.001) and sensitisation to both perennial allergens and pollen (p<0.001) related to higher FeNO levels. Current smoking (p<0.001) and having both parents smoking during childhood, vs having neither (p<0.001) or only one parent smoking (p=0.002), related to lower FeNO. Women with menarche between 9-11 years of age had lower FeNO than those with menarche between 12-14 years of age (p = 0.03) or 15-17 years of age (p=0.003).
CONCLUSIONS AND CLINICAL RELEVANCE: Interpreting FeNO levels in clinical practice is complex and constitutional determinants, as well as smoking and IgE sensitization, are of importance in asthmatic subjects and should be accounted for when interpreting FeNO levels. Furthermore, menarche age and parental smoking during childhood and their effects on lowering FeNO deserve further studies.
2016. Vol. 46, no 9, 1185-1193 p.