- Design
- prospective controlled study with 16S rRNA sequencing and salivary enzyme assays
- Population
- 67 patients with impedance-pH confirmed laryngopharyngeal reflux disease and 44 asymptomatic controls
- Primary outcome
- salivary microbiome composition and digestive enzyme profile
- Effect
- reduced Shannon diversity at family and genus level (P < .006), distinct beta diversity (PERMANOVA P ≤ .005), raised elastase and salivary pH in patients
Sixty-seven patients with laryngopharyngeal reflux disease confirmed on 24-hour hypopharyngeal-oesophageal impedance-pH testing and 44 asymptomatic controls provided saliva for digestive enzyme measurement and 16S rRNA microbiome sequencing, with reflux symptom and sign scores before and after treatment.
Patients had higher salivary elastase, higher salivary pH and lower cholesterol than controls. The microbiome differed at both levels of analysis: reduced Shannon diversity at family and genus level (P < .006) and distinct community composition on UniFrac and PERMANOVA (P ≤ .005). Specific taxa moved — modulation of Streptococcus species, raised Actinomyces and Abiotrophia, depleted Oribacterium and the Eubacterium nodatum group. Elastase, trypsin and bile salts each correlated with the abundance of particular bacteria.
The authors call it preliminary and it is. Laryngopharyngeal reflux is diagnosed badly — often on symptoms alone, often treated with proton pump inhibitors for months without confirmation — so a biological signature is worth having. But cross-sectional differences between symptomatic patients and asymptomatic controls do not establish a direction, and nothing here is close to a diagnostic threshold you could apply to a single patient.
- Keep impedance-pH testing as the confirmatory investigation where the diagnosis matters
- Do not order salivary pepsin or microbiome panels — none is validated for diagnosis
- Reconsider open-ended proton pump inhibitor courses started on symptoms alone
- Note the enzyme findings: elastase, not pepsin, separated the groups most clearly here
Why it matters
It is the first coherent biological description of a condition currently diagnosed and treated almost entirely on symptoms.
Don't overread it
Cross-sectional and preliminary — it cannot show whether the microbial changes cause reflux disease or result from it.
The statistics, in plain English
Alpha and beta diversity differences tell you two groups differ on average as populations. They say nothing about whether an individual's sample could be classified, which is what a diagnostic test has to do. With 67 patients and 44 controls and many taxa examined, some of the individual taxon findings will not replicate.
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