Exhaled nitric oxide: Independent effects of atopy, smoking, respiratory tract infection, gender and height

Abstract

Measurement of exhaled nitric oxide is widely used in respiratory research and clinical practice, especially in patients with asthma. However, interpretation is often difficult, due to common interfering factors, and little is known about interactions between factors. We assessed the influences and interactions of factors such as smoking, respiratory tract infections and respiratory allergy concerning exhaled nitric oxide values, with the aim to derive a scheme for adjustment. We studied 897 subjects (514 females, 383 males; mean age+/-standard deviation 34.5+/-13.0 years) with and without respiratory allergy (allergic rhinitis and/or asthma), smoking and respiratory tract infection. Logarithmic nitric oxide levels were described by an additive model comprising respiratory allergy, smoking, respiratory tract infection, gender and height (p0.001 each), without significant interaction terms. Geometric mean was 17.5ppb in a healthy female non smoker of height 170cm, whereby respiratory allergy corresponded to a change by factor 1.50, smoking 0.63, infection 1.24, male gender 1.17, and each 10cm increase (decrease) in height to 1.11 (0.90). Factors were virtually identical when excluding asthma and using the category allergic rhinitis instead of respiratory allergy (n=863). Within each category formed by combinations of these different predictors, the range of residual variation was approximately constant. We conclude that the factors influencing exhaled nitric oxide, which we analyzed, act independently of each other. Thus, circumstances such as smoking and respiratory tract infection do not appear to affect the usefulness of exhaled nitric oxide, provided that appropriate factors for adjustment are applied.

Physiological Responses to Acute Airborne Particle Exposure during Maximal Aerobic Power

“…Statistically similar eNO initial values were measured for both low and high exposure tests (17.1 ± 6.3 and 15.8 ± 7.9, respectively). Such values were typical of non-atopic, non-smoking adults, whereas higher and lower values are expected for allergic and smoking subjects, respectively, as measured by Travers et al (2007), Dressel et al (2008). Similar eNO trends for high and low exposure scenarios were measured.…”

Determinants of, and reference equation for, exhaled nitric oxide in the Chinese population

“…There were studies that assessed the reference equations of FeNO in healthy adults and, among these studies [14][15][16][17][18], only one involved healthy nonsmoking adults as in our study [14]. Many studies involved subjects who were current smokers or ex-smokers, with airway diseases or respiratory tract infections [15,16,18,21,22]. For example, a study from Germany included current smokers, asthma subjects and subjects with respiratory tract infections (in 24.3%, 3.8% and 20.2%, respectively, among the 897 subjects) [15].…”

“…Previous studies on reference values of FeNO in the general population were mainly limited to children [11][12][13]. There are limited data on the reference value of FeNO in the adult population [14][15][16][17][18], and there is very limited information on FeNO in a healthy, nonsmoking Chinese population. FeNO is a promising noninvasive marker for the assessment of airway inflammation, especially for asthma.…”

Comparison of Orally Exhaled Nitric Oxide in Allergic versus Nonallergic Rhinitis

“…Although duration of rhinitis does not seem to be an important factor in determining elevated FeNO, severity and seasonality of rhinitis as well as coexisting asthma and ocular symptoms were found to be associated with FeNO, in our atopic and nonatopic patients. Dressel et al suggested that respiratory allergy, smoking, respiratory tract infection, male gender, and height are independent factors of increased FeNO levels, 23 and others explained the association between FeNO and gender by differences in height. 24 Conversely, gender, but not height, has been reported as a determinant of FeNO in adults.…”