HSC Section 6 Nov2016 Green Book

patients; however, continued acid reflux was not seen in any patient. Our data are in agreement with two prior studies; one showing that continued acid reflux is a rar- ity on twice daily PPI therapy, 27 and the other showing continued nonacid reflux by impedance testing in 37% of patients refractory to PPI therapy. 12 More important, we could not identify any off therapy traditionally employed physiologic parameter that could predict the on therapy impedance findings. Furthermore, patients with more severe reflux by pH testing defined as % time pH < 4 of greater than 10% had similar impedance parameters than those with no or mild reflux at baseline (Fig. 4). Thus, it appears that the impedance parameters do not correlate with any of the traditionally employed tools in assessing reflux severity. For example, it has been shown that patients with hiatal hernia typically have higher reflux scores compared to those without hiatal hernia, 28 esophagitis severity is expected to correlate with hiatal hernia size and esophageal acid exposure, 29 and % time pH < 4 increases in a graded fashion across the GERD spectrum. 30 Thus, given the lack of any corre- lation between impedance results and these traditional markers, we urge caution regarding the clinical rele- vance of impedance testing. Our study is unique in that the same patient popu- lation underwent physiologic testing off and on PPI therapy. However, some limitations of our study should also be highlighted. First, the results from our study underscore the need for larger outcome studies among patients with refractory symptoms and abnormal imped- ance testing. Second, our present analysis discusses the impedance findings with respect to abnormal number of reflux events in the distal esophagus. We did not evalu- ate proximal extent and liquid, gas, or mixed nature of the refluxate, as some believe may be important in a subgroup of treatment-resistant patients. 31 Additionally, we have used number of reflux events as the primary measure as opposed to SI or SAP. However, the use of SI and SAP is problematic in this group since patients have already declared lack of clinical response to aggressive acid suppression, and recent studies suggest that these metrics may not be reliable or reproducible. 24,25 CONCLUSION In a unique group of patients who had both off ther- apy traditional esophageal physiologic testing and on therapy impedance monitoring, our study shows limited correlation between the latter results with the former previously recognized and employed methodologies. There remains uncertainty regarding the clinical utility of impedance testing among patients with extraesopha- geal symptoms, and we recommend caution in over- interpretation of impedance pH monitoring data. BIBLIOGRAPHY 1. Dent J, El-Serag HB, Wallander MA, Johansson S. Epidemiology of gas- tro-oesophageal reflux disease: a systematic review. Gut 2005;54: 710–717. 2. Locke GR 3rd, Talley NJ, Fett SL, Zinsmeister AR, Melton LJ 3rd. Preva- lence and clinical spectrum of gastroesophageal reflux: a population- based study in Olmsted County, Minnesota. Gastroenterology 1997;112: 1448–1456.

therapy, impedance testing results on therapy cannot be predicted from customary baseline parameters, except among patients with esophagitis in whom the correlation was weak at best, with only 19% of the population hav- ing esophagitis. Our data suggests that impedance parameters on therapy do not correlate well with any reflux parameters previously employed to assess disease severity. Thus, we urge caution regarding the over-inter- pretation of impedance parameters, as the clinical relevance of impedance testing remains unclear at this time. The presence of non- or weakly acidic reflux in patients on PPI therapy is suggested to imply continued reflux and the need for additional therapies. 10,11 In a group of 19 patients who had positive symptom associa- tion with acid or nonacid reflux on impedance testing, a retrospective phone interview study suggested 94% fun- doplication success. 23 However, two recent prospective trials have questioned the clinical reliability of symptom indices in reflux disease. 24,25 Furthermore, the most recent surgical trial in patients with extraesophageal syndrome showed that impedance parameters on ther- apy did not predict symptom response postfundoplication. 26 In this study, the traditional pa- rameters of increased acid exposure, presence of hiatal hernia, and typical reflux symptoms (heartburn and re- gurgitation) were predictive of extraesophageal symptom response to fundoplication. Important controversy in patients with continued symptoms, despite aggressive PPI therapy, is whether to conduct testing on or off PPI therapy. Employing both impedance-pH monitoring on therapy and wireless pH monitoring off therapy in the same group of patients with PPI-refractory symptoms, we confirmed that non- or weakly acid reflux may be present in up to 35% of Fig. 4. Impedance parameters dichotomized by severity of base- line acid reflux. The impedance parameters were no different in those with no or mild reflux (defined as % total time pH < 4 of less than or equal to 10%) compared to those with moderate to severe reflux ( > 10% acid reflux).

Laryngoscope 123: October 2013

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