Volatile Organic Compounds for the Assessment of Liver Disease: Assessment of Hepatobiliary Disease Through Non-Invasive Detection of Exhaled Volatile Organic Compounds

Volatile organic compound (VOCs) emitted from the human body have been of interest to researchers for several decades. In 1971, Pauling et al reported that breath and urine contained approximately 250 and 280 VOCs respectively in normal human subjects. VOCs are traditionally measured in food industry and counter-terrorism. Routine clinical applications include the alcohol breathalyser, 13-C urea breath test for H. pylori, nitric oxide in asthma, and hydrogen/methane test for bacteria overgrowth.

Preliminary work has suggested that there is alteration in the VOC profile of patients with liver disease. It is suggested that as fibrosis increases, liver function is impaired, resulting in increased levels of certain compounds. These compounds are then present at higher levels within the blood stream and when they reach the lungs, they are exhaled. There has also been work demonstrating a change in the profile of VOCs within cancers, demonstrating specific "breath signatures" in patients with oesophageal cancer. At Imperial College London, Marker et al have developed a breath test as screening test for oesophageal cancer with comparable sensitivity and specificity to other screening methods (e.g. faecal occult blood testing). The investigators would aim to achieve similar with hepatobiliary disease via a prospective cross-sectional study aimed at determining the diagnostic accuracy of exhaled breath volatile organic compounds (VOC) for the detection of liver disease.

Patients will be recruited from outpatient clinics and hospital wards based across Imperial College Healthcare Trust. They may also be recruited from the radiology department when attending for liver biopsies or hepatocellular carcinoma surveillance ultrasound scans. When attending for their appointment, a member of the research team will discuss the research project with the patient, explain that is requires the patient to provide a breath +/- urine sample. Patients will be provided with a patient information leaflet. If the patient is to agree to this, they will be asked to sign a written consent form. If a recent PHES test has not been performed, one will be conducted otherwise no additional investigations, invasive or otherwise will be required of the patients.

For patients under regular follow up within the trust, they may be asked to consent to further breath samples being taken at future appointments to facilitate longitudinal follow up. Patients will be entitled to withdraw at any point.

Patients attending for endoscopy, fibroscan or liver biopsy will have been nil by mouth for 4-6 hours prior to the procedure as per local guidelines. For those attending outpatient appointments, if identified prior to their appointment by their clinical team, the investigators will aim to contact the patients and request that they fast. Should they not be fasted, they may be asked to perform basic oral hygiene techniques (e.g. rinsing mouth with water), prior to the breath sample being taken. A food diary of the preceding 24 hours will be taken as part of the pre-sampling questionnaire.