Peptest for diagnosing gastro‑oesophageal reflux

The Peptest is a non‑invasive, near patient test to help diagnose gastro‑oesophageal reflux disease (GORD) including extra‑oesophageal reflux, by detecting pepsin in saliva or sputum.

Most patients are diagnosed with GORD based on their symptoms alone. A salivary test for pepsin could be used in patients who remain symptomatic after empirical acid suppressing treatment, or who have atypical ear, nose and throat symptoms of GORD.

One cross‑sectional study (Ocak et al. 2015) evaluated the accuracy of pepsin detection in saliva using the Peptest in 20 people with suspected laryngopharyngeal reflux. The Peptest was reported to have a sensitivity of 33% and a specificity of 100% compared with pH monitoring.

One prospective controlled cohort study (Hayat et al. 2015) tested the Peptest's ability to discriminate between people with GORD (n=58), people with hypersensitive oesophagus (n=26) and people with functional heartburn (n=27). The diagnostic accuracy of Peptest compared with pH MII monitoring for GORD was not reported, but equates to a sensitivity of 78% and specificity of 62%.

One case‑control study (Hayat et al. 2014) used the Peptest to measure the pharynx's exposure to pepsin in patients with reflux‑related hoarseness (n=21) and people with no symptoms (n=10). Each patient gave 5 saliva samples over 24 hours. The symptomatic group had 28 positive samples from 13 of 21 patients, compared with 6 positive samples from 4 of 10 asymptomatic patients. The samples from symptomatic patients were more likely to test positive than those from the control group (26.7% compared with 12%, p=0.025).

Overall, there is limited published evidence on the diagnostic accuracy of the Peptest for GORD and laryngopharyngeal reflux, and it is uncertain how generalisable it is to the test's likely place in therapy.

Patient‑collected samples can be either processed locally, if suitable laboratory equipment is available for sample preparation, or posted to the manufacturer, RD Biomed, for testing in its laboratory.

A bench‑top vortex mixer and micro‑centrifuge are needed for processing samples locally, and will give a qualitative result. An electronic lateral flow device reader is also needed to give a quantitative result.

The Peptest has a limit of pepsin detection of 16 ng/ml. There is no agreed normal range for pepsin levels in saliva.

After sample processing, qualitative results are ready in 15 minutes.

Each Peptest costs £10 to £17 for local testing.

An electronic lateral flow device reader (for quantitative analysis) costs £1100 (excluding VAT).

For samples sent to the manufacturer's laboratory, testing costs £41.66 for 2 samples or £60.00 for 3 samples.

Because pepsin concentration varies throughout the day, the manufacturer recommends that 3 samples are taken over 1–2 days to confirm diagnosis.