# Obstructive sleep apnea, CPAP therapy, and gastroesophageal reflux symptoms: evidence from a prospective cohort study

## TL;DR

This study shows that sleep apnea severity and nighttime oxygen drops are linked to worse acid reflux symptoms, and that CPAP therapy can significantly reduce these symptoms over time.

## Contribution

The study provides new evidence that hypoxic burden, not just apnea frequency, predicts reflux severity and that CPAP therapy leads to sustained improvement.

## Key findings

- GERD prevalence was 29.0% in the cohort, with symptoms worsening as OSA severity and hypoxemia increased.
- CPAP therapy reduced GERD symptoms progressively, with 69.6% of patients showing meaningful improvement after 6 months.
- Nocturnal hypoxemia metrics (T90%, ODI) were stronger predictors of reflux severity than traditional OSA measures like AHI.

## Abstract

Obstructive sleep apnea (OSA) frequently coexists with gastroesophageal reflux disease (GERD), yet the degree to which hypoxic burden contributes to reflux severity and whether symptoms improve with continuous positive airway pressure (CPAP) remains insufficiently defined. Objective: To investigate the cross-sectional associations of OSA severity and nocturnal hypoxic burden with GERD symptom presence and severity, and to evaluate longitudinal changes in reflux symptoms after CPAP therapy in a prospective follow-up cohort.

In a prospective cohort of adults undergoing polysomnography, 580 participants were evaluated at baseline and stratified by GERD status using the GERD-Q (≥8 indicating GERD). OSA severity (apnea–hypopnea index, AHI) and nocturnal hypoxemia burden (T90%, minimum SpO₂, oxygen desaturation index) were compared across reflux strata. Multivariable linear and logistic regression models assessed continuous associations between sleep parameters and GERD severity. A CPAP sub-cohort of moderate-to-severe OSA with concomitant reflux (n = 150; completed follow-up, n = 112) was monitored for GERD-Q changes at 3 and 6 months.

GERD prevalence reached 29.0%. GERD-Q scores demonstrated dose–response escalation across both OSA severity and hypoxemia categories (p for trend <0.001). T90% and ODI showed stronger associations with reflux burden than AHI in fully adjusted models (T90% β = 0.81; ODI β = 0.44; both p < 0.001), while minimum SpO₂ remained inversely related (β = −0.18; p = 0.003). Logistic models confirmed increased GERD risk in moderate (OR = 1.87) and severe OSA (OR = 2.74), and in patients with marked nocturnal hypoxemia (T90 > 10%; OR = 3.42; all p < 0.001). CPAP therapy yielded progressive symptom reduction (GERD-Q − 1.92 at 3 months; −3.28 at 6 months), with clinically meaningful improvement in 69.6% at 6 months.

OSA severity and nocturnal desaturation jointly predict reflux symptom burden, with hypoxic load outperforming event frequency. CPAP produced sustained GERD symptom improvement over 6 months.