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Background: Acid exposure time (AET) is considered the most useful parameter to predict response of reflux-related heartburn to medical or surgical treatment. However, recent studies showed high rates of heartburn response to proton pump inhibitor (PPI) therapy in patients with normal AET. We aimed to compare the efficacy of postreflux swallow-induced peristaltic wave (PSPW) index and mean nocturnal baseline impedance (MNBI) with AET in linking PPI-responsive heartburn to reflux., Methods: Off-therapy impedance-pH tracings from 425 patients, 317 with PPI-responsive and 108 with PPI-refractory heartburn were blindly re-analyzed. Demographic and endoscopic characteristics, conventional impedance-pH variables, PSPW index, and MNBI were assessed with multivariate logistic regression to identify factors independently associated with PPI responsiveness. Prediction models were developed to assess the strength of reflux linkage with factors independently associated with PPI responsiveness by calculating the area under the curve (AUC) at receiver-operating-characteristic (ROC) analysis., Key Results: At multivariate logistic regression analysis, AET, MNBI, and PSPW index were the only factors independently associated with PPI responsiveness, abnormal values found in 60%, 76%, and 92% of PPI-responsive cases (P<.017). At ROC analysis, PSPW index (AUC:.794, P=.002) and MNBI (AUC: 0.742, P=.003), both separately and combined (AUC: 0.811, P<.001) linked reflux with PPI-responsiveness better than AET (AUC: 0.687)., Conclusions & Inferences: AET, PSPW index, and MNBI are independently associated with PPI-responsive heartburn. PSPW index and MNBI can link PPI-responsive heartburn to reflux better than AET and should become part of the standard analysis of impedance-pH tracings., (© 2017 John Wiley & Sons Ltd.)

Heartburn is the most specific symptom of gastroesophageal reflux disease (GERD). In clinical practice, heartburn relief by a proton pump inhibitor (PPI) trial does suffice to confirm GERD. However, an objective diagnosis of GERD is required before anti-reflux endoscopic or surgical interventions, independently from PPI response. Thus, since normal findings at upper endoscopy are detected in the majority of patients with heartburn, reflux monitoring is often required. When traditional catheter-based or wireless pH tests are used, reflux episodes are conventionally identified by pH drops below 4.0 units. Combined impedance-pH monitoring has the advantage to provide a comprehensive assessment of both physical and chemical properties of refluxate and the distinction between acid and weakly acidic refluxes, both proven to cause heartburn. Unfortunately, the conventional impedance-pH parameters, namely acid exposure time and number of reflux events, are characterized by suboptimal diagnostic sensitivity, and the reliability of symptom-reflux association indexes remains questionable. Therefore, novel impedance parameters, namely the post-reflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI), have recently been proposed in order to achieve a better diagnostic yield. In fact, they proved to be highly accurate in distinguishing reflux-related from reflux-unrelated heartburn, off- as well as on-PPI therapy. Currently, manual review of impedance-pH tracings is needed because of the modest accuracy of available software tools for automated analysis. PSPW index and MNBI are highly applicable and reproducible, and their calculation requires a few additional minutes during the manual review of impedance-pH tracings. So far, we believe that PSPW index and MNBI are ready for prime time and should become part of the standard analysis of impedance-pH tracings for GERD diagnosis in patients with endoscopy-negative heartburn. [ABSTRACT FROM AUTHOR]

Background On-therapy impedance- pH monitoring in proton pump inhibitor ( PPI)-refractory gastroesophageal reflux disease ( GERD) yielded conflicting results. We aimed to assess the diagnostic value of postreflux swallow-induced peristaltic wave ( PSPW) index and mean nocturnal baseline impedance ( MNBI) in PPI-refractory heartburn. Methods On-therapy impedance- pH tracings from 189 consecutive patients with PPI-refractory heartburn were blindly reviewed. Patients were subdivided into refractory reflux esophagitis ( RRE), healed reflux esophagitis ( HRE), non-erosive reflux disease ( NERD), and functional heartburn ( FH) according to endoscopic and conventional impedance- pH findings. The diagnostic accuracy of PSPW index and MNBI in separating NERD from FH was assessed with receiver-operating-characteristic ( ROC) analysis. Objectively documented persistent reflux remission at 3-year follow-up in 53 patients who underwent laparoscopic fundoplication served to evaluate PSPW index and MNBI as independent predictors of PPI-refractory GERD confirmed by positive surgical outcome. Key Results Median PSPW index and MNBI values were significantly lower in 39 RRE (16%; 1145 Ω) than in 41 HRE (25%; 1741 Ω) and in 68 NERD (29%; 2374 Ω) patients, and in all three GERD subgroups compared to 41 FH cases (67%; 3488 Ω) ( P<.008). At ROC analysis, comparing NERD to FH the area under the curve was 0.886 with PSPW index and 0.677 with MNBI ( P=.005). PSPW index was an independent predictor of PPI-refractory GERD (odds ratio 0.6983, P=.012). Conclusions & Inferences At on-therapy impedance- pH monitoring, PSPW index and MNBI efficiently distinguish PPI-refractory NERD from FH. The PSPW index represents an independent predictor of PPI-refractory GERD. [ABSTRACT FROM AUTHOR]