Mean nocturnal baseline impedance correlates with reflux disease severity but not symptoms

Introduction The Lyon Consensus 2018 describes nocturnal baseline impedance (MNBI) as a reflection of oesophageal mucosa permeability, with lower values found in erosive than non-erosive reflux disease (NERD); however it is not clear how MNBI correlates with symptoms. This study aims to determine the relationship of MNBI across three common presentations of reflux; Barrett’s oesophagus, NERD and functional heartburn (FH). Methods Between 2014 and 2020, pH-Impedance measurements and symptom index (SI) were collected for 37 consecutive patients with at least 3 cm of Barrett’s oesophagus (13 on and 24 off proton pump inhibitors; PPI). 37 consecutive patients with NERD and 37 with FH were also included for comparison. MNBI was calculated from sensors at 3 and 5 cm above the LOS over 3 × 10 minute intervals during the nocturnal period. Results There was a significant difference in median acid exposure time (AET) between the 3 subgroups; Barrett’s (14.0%(6.3%,23.5%), NERD (8.9%(5.6%13.5%) and FH (1.9(0.7%, 2.7%) (p MNBI was low in Barrett’s compared to NERD and FH (figure 1; p 3 cm) Barrett’s who had attempts at therapy (ablation, mucosal resection) compared to the 27 who had not received therapy (p=0.96). There was a moderately inverse correlation between Barrett’s segment length (median 5 cm (3 cm,9 cm) and MNBI (r = -0.436; p=0.038). Conclusion This study suggests that the impact of reflux disease on mucosal permeability (MNBI) may have an influence on symptom perception. Both MNBI and symptom perception were significantly reduced in Barrett’s compared to NERD. Furthermore, neither MNBI nor symptom perception are affected by use of acid reducing medication despite the difference in AET. This study provides further validation to the Lyon consensus definition of MNBI as a measure of reflux disease severity.