Comment on "Impairment of chemical clearance is relevant to the pathogenesis of refractory reflux oesophagitis" by Marzio Frazzoni et al. [Digestive and Liver Disease 2014;46:596-602]

We read with great interest the paper by Frazzoni et al. [1] on the role of chemical clearance in the pathogenesis of proton pump inhibitor (PPI)-refractory reflux oesophagitis (RRO). Indeed, the authors using the state-of-the-art technique to assess gastroesophageal reflux, that is impedance-pH monitoring, investigated 29 patients with RRO, 18 with healed oesophagitis (HRO) and 49 with well-defined non-erosive reflux disease (NERD) according to the more recent guidelines [2] and [3], and found that gastric acid exposure time, oesophageal acid exposure time, the number of total, acid and weakly acidic refluxes, bolus exposure and clearance time did not differ among RRO, HRO, and NERD patients. Moreover, they observed that only a new impedance parameter, the postreflux swallow-induced peristaltic wave (PSPW) index, was significantly lower in RRO patients than in either HRO or NERD patients. This data emphasized that impairment of chemical clearance is relevant to the pathogenesis of RRO. We congratulate with the authors as they provide novel insights in the PPI-resistance area, which represents one the most important challenges in our clinical practice. Moreover, they provide convincing data on a further important topic, that is the diagnosis and classification of NERD patients [4] and [5]. However, although this study is very accurate and clear, some data were not reported. Indeed, data on mean acid clearance time (MACT) in the different groups of studied patients are lacking. MACT reflects the ability of the oesophagus to clear its content after multiple acidic reflux events have occurred and, thus, its value may be associated to that of PSPW, although its significance is limited to the evaluation of acidic refluxate. Moreover, information on manometric patterns (i.e. frequency of ineffective oesophageal motility) are lacking and should be provided given the suggested importance of chemical clearance and therefore of peristalsis integrity in RRO patients. Thus, are the data regarding the MACTs and manometric patterns in the different groups available for comparison in order to corroborate the novel findings observed by the authors?