Concordance Between Methods Assessing Symptom-Reflux Association in a Series of pH-Impedance Studies

Abstract

Purpose: Multichannel intraluminal pH-impedance (MII-pH) is a reliable instrument to define acid or non-acid reflux. The demonstration of a symptom-reflux association is generally obtained by two major. Methods: Symptom index (SI) and symptom probability association (SAP). According to various evidences their agreement could be poor: the SI seems to overestimate a positive symptom relationship twofold compared with the SAP. Besides, a remarkable part of patients cannot complain of symptoms during the recording. Aim of our study was to evaluate the impact of symptom-reflux association and the concordance between SI and SAP in a series of NERD outpatients. Methods: We have examined a total of 82 consecutive NERD patients off-PPI therapy using ambulatory 24-hour MII-Ph. Refluxate presence was measured at 3, 5, 7, 9, 15 and 17 cm and esophageal pH at 5 cm above the LES. Total distal esophageal acid exposure time (AET), number of impedance-detected reflux episodes (acid, nonacid) and symptom association parameters were considered. In particular both SI (positive if ≥ 50%) and SAP (positive if ≥ 95%) were calculated in presence of symptoms. Results: Of 82 patients 56 (68%, 42 F, 21-76 yrs) complained of symptoms during the study and were eligible for symptom evaluation. Of 56, 29 patients had typical reflux symptoms, 27 sovraesophageal symptoms. A disagreement between SI and SAP was observed in 9 out 56 studies (16%). In 8 out 9 subjects SAP was the only positive parameter: only one patient had positive SI and negative SAP. No significant differences were found with respect to typical or atypical symptoms although the majority of discordant subject (6 out 9) complained of typical symptoms. Finally none correlation was demonstrated with age, sex and acid/nonacid reflux parameters. Conclusion: In our series a good number of patients complained of symptoms during the impedance study. This is crucial to establish the condition of hypersensitive esophagus in case of negative acid profile. Besides only in a minority of cases, a disagreement between SI and SAP was present and however SAP was almost always positive. Therefore in our series SI did not overestimate symptom relationship. If we consider that SAP is the only parameter utilized in the majority of MII-pH classifications, a SI-SAP discordance is a negligible problem in our clinical experience.