title: Exhaled carbon monoxide levels in atopic asthma: a longitudinal study.
abstract: Exhaled carbon monoxide (eCO) is a potential non-invasive marker of airway inflammation. We have investigated the cross-sectional and longitudinal relationship between eCO and lung function and bronchial reactivity in 69 adults with atopic asthma, in the course of participation in a 6-week randomised placebo-controlled trial of vitamin E supplementation. At baseline, there was no cross-sectional association between absolute eCO levels and either forced expiratory volume (FEV(1)), forced vital capacity (FVC) or bronchial reactivity. However, in the longitudinal analysis within the placebo group, a rise in mean eCO was significantly associated with improvement in bronchial reactivity (change in eCO (parts per million) per natural log unit change in bronchial hyperreactivity 0.498, 95% confidence interval 0.071 to 0.924, P=0.024). These findings suggest that, contrary to previous data, there is no cross-sectional relationship between eCO and lung function or bronchial reactivity, but that there may be a longitudinal trend with bronchial reactivity that is worth further investigation.
authors.affiliation: Division of Respiratory Medicine, University of Nottingham, Clinical Sciences Building, Nottingham NG5 1PB, UK. philip.pearson@nottingham.ac.uk
authors.forename: Philip
authors.initials: P
authors.lastname: Pearson
authors.forename: Sarah
authors.initials: S
authors.lastname: Lewis
authors.forename: John
authors.initials: J
authors.lastname: Britton
authors.forename: Andrew
authors.initials: A
authors.lastname: Fogarty
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000178:diet therapy / Q000378:metabolism* / Q000503:physiopathology; D015415:Biomarkers / Q000378:metabolism; D001944:Breath Tests; D002248:Carbon Monoxide / Q000032:analysis*; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D014797:Vital Capacity; D014810:Vitamin E / Q000627:therapeutic use
chemical_list: D015415:Biomarkers; D014810:Vitamin E; D002248:Carbon Monoxide