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GORD has been defined by international consensus based on symptoms of heartburn and regurgitation.1 While this definition is useful for patients with the typical reflux syndrome, these symptoms may not be present in patients with extra-oesophageal GORD. The limitations of pH testing and endoscopy were highlighted in a recent study that demonstrated that each failed to identify approximately 30% of patients with proven GORD.2 A test that establishes a diagnosis of GORD at low cost with minimal intervention would have great utility. The presence of pepsin in saliva or sputum has been proposed as a surrogate marker for reflux disease, albeit one that tells us nothing about a causal relationship between reflux and symptoms.
Pepsin may be detected in sputum or saliva by enzymatic or immunological tests.3 Enzymatic tests have several limitations and are difficult to obtain and standardise in practice settings. Attention has therefore focused on immunologic assays with polyclonal and monoclonal antibodies that have been patented and commercialised.3
The question for the clinician is whether salivary pepsin determination is a diagnostic tool that is helpful in clinical practice. For a diagnostic test to be useful in clinical practice, we should be able to demonstrate that the test not only improves our accuracy but that it results in a treatment decision that changes patient outcomes.4 Tests that improve accuracy modestly but don't change management or outcomes have little …