Abstract
The search for biomarkers that can guide precision medicine in asthma, particularly those that can be translated to the clinic, has seen recent interest in exhaled volatile organic compounds. Given the number of studies reporting “breathomics” findings and its growing integration in clinical trials, we performed a systematic review of the literature to summarise current evidence and understanding of breathomics technology in asthma.
A PRISMA-oriented systematic search was performed (CRD42017084145) of Medline, Embase and the Cochrane Databases to search for any reports that assessed exhaled volatile organic compounds in adult asthma patients, using the following terms (Asthma AND (Volatile Organic Compounds AND Exhaled) OR Breathomics).
Two authors independently determined the eligibility of 2957 unique records, from which 66 underwent full-text review. Data extraction and risk of bias assessment was performed on the 22 studies deemed to fulfil the search criteria. The studies are described in terms of methodology and the evidence narratively summarised under the following clinical headings: Diagnostics, Phenotyping, Treatment stratification, Treatment monitoring and Exacerbation Prediction/Assessment.
Our review found that most studies were designed to assess diagnostic potential rather than focus on underlying biology or treatable traits. Results are generally limited by a lack of methodological standardisation, external validation and insufficiently powered studies, but there is consistency across the literature that exhaled VOCs are sensitive to underlying inflammation. Modern studies are applying robust breath analysis workflows to large multi-centre study designs, which should unlock the full potential of measurement of exhaled volatile organic compounds in airways diseases such as asthma.
Footnotes
This manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.
Conflict of interest: Dr. Azim has nothing to disclose.
Conflict of interest: Ms. Barber has nothing to disclose.
Conflict of interest: Dr. Dennison has nothing to disclose.
Conflict of interest: Dr. Riley reports and works for and has shares in GSK.
Conflict of interest: Dr. Howarth reports and works for GSK in an educational role and has shares in GSK.
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