Abstract
AIM: To study the effect of positive airway pressure (PAP) treatment on nocturnal gastro-oesophageal reflux (nGOR) and respiratory symptoms among clinical obstructive sleep apnoea (OSA) patients. METHODS: 822 patients newly diagnosed with OSA referred for PAP treatment were recruited. 732 patients had a 2-year follow-up visit with continuous PAP compliance data (366 full PAP users, 366 partial/non-PAP users). They answered questionnaires, including reporting of nGOR, sleep and respiratory symptoms and general health. Patients with nGOR symptoms once a week or more were defined as "with nGOR". Those without nGOR symptoms and nGOR medication were defined as "no nGOR". Others were defined as "possible nGOR". RESULTS: At 2-year follow-up, PAP treatment among full users resulted in decreased nGOR (adjusted OR 0.58, 95% CI 0.40-0.86) and wheezing (adjusted OR 0.56, 95% CI 0.35-0.88) compared with partial/non-PAP users. Decreased nGOR, among both full and partial/non-users of PAP treatment, was associated with a decrease in productive morning cough (adjusted OR 4.70, 95% CI 2.22-9.99) and a decrease in chronic bronchitis (adjusted OR 3.86, 95% CI 1.74-8.58), but not decreased wheezing (adjusted OR 0.90, 95% CI 0.39-2.08). A mediation analysis found that PAP treatment directly led to a decrease in wheezing, not mediated through nGOR. Conversely, PAP treatment decreased productive cough mediated through a decrease in nGOR. CONCLUSION: In an unselected group of OSA patients, PAP treatment for 2 years was associated with a decrease in nGOR and respiratory symptoms. The PAP treatment itself was associated with less wheezing. A decrease in nGOR through PAP treatment was associated with a decrease in productive cough.