View - ResearchSpace@Auckland - The University of Auckland

exhaled NO was the best predictor, when compared to lung function testing and
bronchodilator response, to discriminate those who subsequently developed asthma with the
sensitivity of g6vo and a specificity of g27o at a cut off level chosen 1.5 standard deviations
above the average for controls (Malmberg2004)'
g.8.4 Is nitic oxid.e associatedwith symptoms and severiry of asthma?
positive correlations with exhaled No have been shown with bronchodilator use and
symptom scores (Lanz,Irung et al. 1997; Tsujino, Nishimura et al. 2000; Roberts, Hurley et
a:.2004;warke, Mairs et a,..2004: Pijnenburg, Bakker et al. 2005; spergel, Fogg et al' 2005;
prasad, Langford et al. 2006), cough (Li, Irx et al. 2003) and bronchodilator responsiveness
(Colon-Semidey, Marshik et al. 2000; Little, Chalmers et al' 2000; Dupont' Demedts et al'
2xl3;Malmberg, Pelkonen et al. 2003; Silvestri, sabatini et al. 2003; Pijnenburg, Bakker et
al. 2005; Fujimoto, Yamaguchi et al. 2006; Zietkowski, Bodzenta-Lukaszyk et al' 2006)' In
many of the studies, the No levels and the sputum eosinophil levels had stronger correlations
to symptoms than other parameters measured. Again the findings were not universal' For
example, in some studies no correlation was seen between NO and bronchial hyper-
responsiveness (al-Ali, Eames et al. 1998; Silkoff, Mcclean et al. 1998; Chan-Yeung' obata
et al. 1999; van Rensen, Straathof et al. t999;Ho, Wood et al. 2000; Silvestri, Spallarossa et
al. 2000; del Giudice, Brunese et a:.2004:Thomas, Gibson et al. 2005; Jentzsch, le Bourgeois
et al. 2006), NO and symptoms (al-Ali, Eames et al. 1998; Griese, Koch et al' 2000; Sippel'
Holden et al. 2000) or NO and medication use (al-Ali, Eames et al. 1998; Sippel, Holden et al'
2000). In addition, no relationship was determined in 77 adult asthmatics between exhaled
NO and quality of life (Ehrs, Sundblad et al' 2006)'
There are a number of possible explanations for the inconsistencies. Firstly, the correlation
with severity is difficult depending on how 'severity' is defined' we know that exhaled No is
higher in steroid naive asthmatics, so those on increased amounts of treatment may have
reduced levels of No but their requirement for higher IHCS doses or additional medications
to control symptoms deems them more 'severe'. Several studies using either the GINA
guidelines or the ATS asthma guidelines to categorize asthmatic patients into gradations of
severity have been unable to show a relationship to exhaled No levels in adults (stirling'
Kharitonov et al. 1998; Chan-Yeung, obata et al. Iggg; Lim, Jatakanon et al' 2000; sippel'
Holden et al. 2000) or in children (Griese, Koch et al. 2000)' In one study of 30 children
divided into mild, moderate and severe groups' the exhaled NO did appear to correlate with
asthma severity (Delgado-Corcoran' Kissoon et al' 2004), and those on oral steroids with
229