Important non‐disease‐related determinants of exhaled nitric oxide levels in mild asthma – results from the Swedish GA²LEN study

Abstract

Summary Background Fractional exhaled nitric oxide (FeNO) has a potential clinical role in asthma management. Constitutive factors such as age, height and gender, as well as individual characteristics, such as IgE sensitization and smoking, affect the 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 Fractional exhaled nitric oxide was measured in 557 subjects with asthma from the Swedish GA2LEN study. Allergic sensitization was assessed by skin prick tests to most common aeroallergens. Upper airway comorbidities, smoking habits, smoking exposure during childhood and hormonal status (for women) were questionnaire‐assessed. Results Male gender (P < 0.001), greater height (P < 0.001) and sensitization to both perennial allergens and pollen (P < 0.001) are 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), are related to lower FeNO. Women with menarche between 9 and 11 years of age had lower FeNO than those with menarche between 12 and 14 years of age (P = 0.03) or 15 and 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 sensitisation, 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.

Overall and peripheral lung function assessment by spirometry and forced oscillation technique in relation to asthma diagnosis and control

“…With regard to the relationship between lung function and airway inflammation, a more negative X5 associated in asthmatic individuals with higher FeNO 50 , a finding which is in line with previous studies . Classic lung function did not associate with FeNO 50 , and this corroborates the findings from a recent large study in adults, but contradicts our previous findings . The strength of the present study is that it is one of the largest studies to date to compare FOT and spirometry in both children and adults.…”

Determinants of fractional exhaled nitric oxide in healthy men and women from the European Community Respiratory Health Survey III

“…Taylor et al studied 895 healthy adults at age 32 years and found that men had approximately 25% higher F E NO levels than women (15.5 vs 11.6 ppb). A similar size of the sex difference has also been reported in asthmatic subjectsfor example, Al‐shamkhi et al reported that in 557 subjects with asthma from the Swedish GA2LEN study, men had 32% higher F E NO levels than women (24.0 vs 16.4 ppb). However, not all studies have been able to detect sex differences in F E NO .…”

“…In our study, F E NO levels were 21% higher in men than women (18.2 vs 15.0 ppb). Several previous studies have also reported an association between increased F E NO levels and male sex . Kim et al reported, based on data from 166 healthy Korean adults (aged 20‐68 years), that men had 27% higher F E NO levels than women (35.7 vs 26.0 ppb).…”

Developments in the field of allergy in 2016 through the eyes of Clinical and Experimental Allergy

“…Finally, Al‐shamkhi et al have confirmed that the previously reported environmental and demographic factors that influence FeNO in healthy populations also apply to those with mild asthma. Two novel additional factors, age of menarche and parental smoking, also appear to lower FeNO in this population.…”