Introduction Patients suffering from gastro-oesophageal reflux disease (GORD) can be categorised into those suffering from a purely daytime (DAY), purely nocturnal (NOCT) or combined reflux pattern. Despite identifying a dominant pattern of reflux the treatment strategies are not specifically targeting a specific type reflux pattern. This may expose patients to treatments which may not necessarily be beneficial to that particular pattern of reflux. Possible factors affecting different patterns of reflux may include abnormal oesophageal motility, lower oesophageal sphincter (LOS) length, presence of a hiatus hernia or too short of a time gap between meal and sleep. We aimed to determine the mechanisms behind patients suffering from purely nocturnal reflux compared to purely daytime reflux.

Methods Patients who underwent High Resolution Manometry (HRM) in an outpatients clinic from December 2014 to November 2015 were retrospectively grouped into those with purely nocturnal reflux and those with purely daytime reflux as measured by 24 hour ambulatory pH-impendance monitoring. Comparisons were made between the two groups using Fisher’s exact tests and receiver operating characteristic (ROC) curves for LOS baseline pressure, LOS length, meal-sleep time gap, presence of a hiatus hernia, oesophageal motility disorders, age and gender. A P value <0.05 was considered as significant.

Results 62 patients with purely nocturnal reflux (median age 46.5, 27 male) and 32 patients with purely daytime reflux (median age 60, 15 male) were included. HRM diagnosis were not significantly different between these two groups (53% ineffective oesophageal motility (IOM) in NOCT and 50% IOM in DAY patients, P = 0.8). There was also no significant difference between the two groups in terms of prevalence of a hiatus hernia (P = 0.4), LOS length (P = 0.1), LOS mean or min baseline pressure (P = 0.6 for both). However, the meal-sleep time gap appeared to be significantly different between the DAY and NOCT group (148 ± 18 min in DAY vs 107 ± 9 min in NOCT, P = 0.03). Also, younger patients showed a significantly higher rate of nocturnal reflux (<48 year old, had more chance of being NOCT, sensitivity 53%, specificity 79.4%, P = 0.009).

Conclusion In this study we did not find any manometric parameter to be significantly predictive of being a NOCT or DAY patient. Nevertheless, further study is required to explore in more detail the effect of age on pattern of GORD. Previous literature have demonstrated the effect of the meal-sleep time gap which is also confirmed in this study.

Disclosure of Interest None Declared