Background: The importance of weakly acidic and weakly alkaline reflux in gastro-oesophageal reflux disease (GERD) is gaining recognition.
Aim: To quantify the proportions of reflux episodes that are acidic (pH <4), weakly acidic (pH 4-7) and weakly alkaline (pH >7) in adult patients with GERD, and to evaluate their correlation with symptoms.
Methods: Studies were identified by systematic PubMed and Embase searches. Data are presented as sample-size weighted means and 95% confidence intervals.
Results: In patients with GERD taking a proton pump inhibitor (PPI), 80% (76-84%) of reflux episodes were weakly acidic or weakly alkaline and 83% (78-88%) of reflux symptom episodes were associated with weakly acidic or weakly alkaline reflux episodes. In patients with GERD not taking a PPI, 63% (59-67%) of reflux episodes were acidic and 72% (57-87%) of reflux symptom episodes were associated with acid reflux episodes. Six studies presented data separately for weakly alkaline reflux, which accounted for <5% of all reflux episodes, both on and off PPI therapy.
Conclusions: Weakly acidic reflux underlies the majority of reflux episodes in patients with GERD on PPI therapy, and is the main cause of reflux symptoms occurring despite PPI therapy.