Fig. 1
From: Respiratory symptoms, sleep-disordered breathing and biomarkers in nocturnal gastroesophageal reflux
A flow diagram of selection of cases and controls. At the top are subjects at the time of first visit in the ECRHS III study, and at the bottom at follow-up around 5–8 months later. The groups in bold were used for further analysis: Subjects who were symptomatic at baseline and follow-up (persistent nGER), and subjects who were asymptomatic at baseline and follow-up (controls). nGER = nocturnal gastroesophageal reflux