Introduction The diagnostic test Peptest™ detects pepsin, which is exclusively produced by the stomach, in expectorated saliva and is a quick and easy unique marker of the reflux of gastric contents responsible for gastro-oesophageal reflux disease (GORD).¹

A study into the ability of Peptest to detect patients with GORD was performed. The optimal sampling strategy to give the highest diagnostic yield was investigated.

Method Patients attending routine endoscopy clinic at Rotherham General Hospital with symptoms of GORD with erosive oesophagitis (EO) or if the score of the GERDQ²was ≥8. The patients provided 1–10 saliva samples with randomised strategies thats were blindly analysed for the presence of pepsin using Peptest™ and concⁿof pepsin determined (≥16ng/ml).

Results 59 GORD subjects (30M:27F; mean age 57; 83% on PPI) provided 283 expectorated saliva samples of which 149 samples (53%) were Peptest positive representing 47 GORD subjects with at least 1 Peptest positive sample (80%) [significantly greater than a control group¹38%, p < 0.0001 Fisher’s exact test].

Pepsin concⁿranged from 0–500 ng/ml with median 30 ng/ml (IQR 0–164) and mean 94 ng/ml (SD 133) [significantly greater than a control group¹p < 0.0001, Mann Whitney U test].

There were 22 patients with EO, 35 patients with non-erosive reflux disease (NERD) and 2 patients with Barrett’s Oesophagus (BO) with at least 1 sample pepsin positive: 68% for EO (mean 68 ng/ml), 86% for NERD (mean 105 ng/ml) and 100% (mean 152 ng/ml) for BO.

Peptest results based on timing of the sample is given in Table 1.

Conclusion Optimal sampling time for diagnosis of GORD by Peptest is 60 min after a meal or within 15 min of a symptomatic episode. The ease of the test allows for saliva samples to be taken before commencing treatment, but even amongst pre-treated EO patients (where gastroscopy is often negative) Peptest can still recognise the underlying reflux. Peptest, therefore, has the potential to be used as the first line investigation in patients suspected of reflux. Those without ‘alarm’ symptoms and who test ‘positive’ could therefore be managed in general practice. Referral for gastroscopy or for other invasive investigations can be reserved for those for whom there is separate need (e.g. to check BO, if reflux symptoms are refractory, or for opportunistic cancer screening).

Disclosure of interest V. Strugala Employee of: RD Biomed Ltd, P. Dettmar Shareholder of: RD Biomed Ltd, Conflict with: RD Biomed Ltd, K. Bardhan: None Declared. Study was part funded by Technology Strategy Board

References

1. Hayat JO, et al. Gut 2015;64:373–380

2. Jones R, et al. APT 2009;30(10):1030–1038