Evaluation of the pathophysiological association between the GERD and OSAS: Esophageal pH‐monitoring results beyond Lyon criteria

Abstract

Dear Editor,We read with great interest the systematic review and meta-analysis by Chehade et al. that provides an updated picture of the association between gastroesophageal reflux disease (GERD) and obstructive sleep apnea syndrome (OSAS). 1 Their analysis included prevalence studies and case-control comparisons of patients with OSAS and GERD, adjusting for various confounders and different diagnostic methods, and the authors concluded that the association between OSAS and GERD is independent of the modalities to screen or diagnose both disorders. 1 To the best of our knowledge, a contemporary evaluation using pH-impedance monitoring-the current gold standard method for detection of reflux episodes-and polysomnography with the aim to demonstrate a direct association between the two clinical entities has never been reported. In patients suspected of GERD, we therefore conducted a pilot study using nocturnal polysomnography during the 24-h pH-impedance monitoring examination in seven patients (4 males, median age 51 years). Five patients reported typical GERD symptoms (i.e., heartburn or regurgitation), while two patients had atypical manifestations alone. Focusing on respiratory symptoms, the most prevalent was snoring (70%), followed by nocturnal choking (30%) and apnea (30%). According to the Lyon criteria version 2.0, after pH-impedance monitoring we obtained a conclusive diagnosis of GERD in 2 patients, while the median acid exposure time (AET) was 2.3% (IQR 1.1-5) in all patients, with a median total number of refluxes of 41 (IQR 29-91). 2 On the other hand, OSAS was diagnosed in 5 patients (71.4%) according to an apnea hypopnea index (AHI) ≥ 5 points, whose median value was 21 (IQR 4.9-39), with a median number of 102 apneas (2-201) and 72 hypopneas (6-91) of episodes.In order to further explore the potential association between these two conditions, we focused on the relationship between pH-impedance monitoring metrics in recumbent position and AHI values. We found a direct association between higher AHI and AET (odds ratio [OR] 24.2, 95% confidence interval [95% CI] 1.5-388.4, P = 0.032), acid clearing time (OR 1.2, 95% CI 1.1-1.5), bolus clearing time (OR 190.0, 95% CI 15.4-2340.2), and number of reflux episodes (OR 1.8, 95% CI 1.1-3.0) in recumbent position. Moreover, a higher AHI was also associated with higher number of proximal refluxes (OR 1.0 × 10 19 , 95% CI 48.1-1.1 × 110 36 ). No significant association emerged between AHI and pH-impedance monitoring in upright condition and considering the overall exam.The bidirectional relationship between GERD and OSAS aligns with the association we observed between the AHI and the alterations in pH-impedance testing in recumbent patient, thus usu-