The relevance of symptom association analysis in GORD patients undergoing anti-reflux surgery.

To The Editor: We read with great interest the article by Broeders et al (1) on the effects of anti-reflux surgery on weakly acidic reflux and belching. The authors evaluated 31 gastro-oesophageal reflux disease (GORD) patients, refractory to proton pump inhibitors, by means of upper gastrointestinal endoscopy, validated symptoms questionnaires, stationary oesophageal manometry and 24-hour impedance-pH monitoring of antisecretory therapy before and 6 months after laparoscopic Nissen fundoplication (LNF). They observed that LNF reduced oesophageal acid exposure time (AET) and proximal migration of reflux events and similarly controlled both acidic and weakly acidic reflux, while gas reflux was diminished to a lesser extent. Moreover, they found that out of 15 patients with persisting symptoms after LNF, none had a positive symptom index (SI) for both acidic and weakly acidic reflux. The study provides relevant new information regarding a possible explanation of anti-reflux surgery failure; however, we believe that the interpretation of experimental findings would have improved if the results of symptom association analysis (SAP) before LNF were also reported. The recent introduction in clinical practice of impedance-pH monitoring has allowed us to measure all types of reflux, and the diagnostic yield of the technique has been increased using the analysis of the symptom correlation with reflux events, expressed by either SI or SAP. This permits also to distinguish reflux patients from those with functional heartburn.2 These important features are gaining more and more relevance since several recent studies have shown that GORD patients, in particular those with non-erosive reflux disease (NERD), have frequently a normal distal oesophageal AET (3,4). In these situations, the diagnostic importance of multichannel intraluminal impedance-pH testing relies more on establishing the symptom association with both acidic and weakly acidic reflux events than on quantifying reflux episodes. However, we have recently evaluated SAP in patients with both NERD and erosive oesophagitis and have shown that weakly acidic reflux was associated with typical reflux symptoms in 7% of erosive oesophagitis and 6% of NERD patients, respectively, even with abnormal AET (5). These findings are relevant because they indicate that components other than acid in the gastroesophageal refluxate play a role in symptom development in both erosive and non-erosive forms of GORD with abnormal distal oesophageal acid exposure. The above patients are more likely to belong to the group of those who fail to respond to acid suppressive medications and would benefit from anti-reflux surgery (6). So we believe that data concerning the SI or SAP for acidic and weakly acidic reflux should be carefully analysed and clearly reported also preoperatively in all studies evaluating the efficacy of surgery in GORD patients in order to know whether patients refractory to proton pump inhibitors, despite abnormal AET, are hypersensitive to weakly acidic reflux. This would be another point reinforcing the role of surgery in the control of this kind of reflux, which can be diagnosed only by impedance-pH testing. Accordingly, Broeders et al should have also mentioned the preoperative results of SI for both acidic and weakly acidic reflux in their otherwise complete study