Non-invasive phenotyping using exhaled volatile organic compounds in asthma
- Baharudin Ibrahim1,2,
- Maria Basanta1,2,
- Paul Cadden1,2,
- Dave Singh1,2,
- David Douce3,
- Ashley Woodcock1,2,
- Stephen J Fowler1,2,4
- 1Respiratory Research Group, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
- 2NIHR Translational Research Facility in Respiratory Medicine, University Hospital of South Manchester, Manchester, UK
- 3Waters Corporation, Manchester, UK
- 4Lancashire Teaching Hospitals NHS Foundation Trust, Preston, UK
- Correspondence to Stephen J Fowler, Lecturer and Honorary Consultant in Respiratory Medicine, University of Manchester and Lancashire Teaching Hospitals NHS Foundation Trust, Respiratory Research Group, Education and Research Centre, Wythenshawe Hospital, Southmoor Road, Manchester M23 9LT, UK;
- Received 7 December 2010
- Accepted 27 May 2011
- Published Online First 11 July 2011
Background Breath volatile organic compounds (VOCs) may be useful for asthma diagnosis and phenotyping, identifying patients who could benefit from personalised therapeutic strategies. The authors aimed to identify specific patterns of breath VOCs in patients with asthma and in clinically relevant disease phenotypes.
Methods Breath samples were analysed by gas chromatography–mass spectrometry. The Asthma Control Questionnaire was completed, together with lung function and induced sputum cell counts. Breath data were reduced to principal components, and these principal components were used in multiple logistic regression to identify discriminatory models for diagnosis, sputum inflammatory cell profile and asthma control.
Results The authors recruited 35 patients with asthma and 23 matched controls. A model derived from 15 VOCs classified patients with asthma with an accuracy of 86%, and positive and negative predictive values of 0.85 and 0.89, respectively. Models also classified patients with asthma based on the following phenotypes: sputum (obtained in 18 patients with asthma) eosinophilia ≥2% area under the receiver operating characteristics (AUROC) curve 0.98, neutrophilia ≥40% AUROC 0.90 and uncontrolled asthma (Asthma Control Questionnaire ≥1) AUROC 0.96.
Conclusions Detection of characteristic breath VOC profiles could classify patients with asthma versus controls, and clinically relevant disease phenotypes based on sputum inflammatory profile and asthma control. Prospective validation of these models may lead to clinical application of non-invasive breath profiling in asthma.
Funding GlaxoSmithKline kindly contributed towards the funding of this study.
Competing interests None.
Ethics approval This study was conducted with the approval of the Tameside and Glossop REC (now known as North West 8 REC—Greater Manchester East).
Provenance and peer review Not commissioned; externally peer reviewed.