Lipid-Laden Macrophage Index and Gastroesophageal Reflux–Related Respiratory Disease in Children: In Reply

Abstract

We appreciate the comments made by De Boeck et al. To prove the relationship between gastroesophageal reflux disease and respiratory disease in intractable patients is challenging. Our study included a population of symptomatic patients with respiratory symptoms whose conditions did not respond to aggressive medical therapy and in whom a bronchoscopy was clinically indicated. We recognize that this limits the generalizability of the data; however, we feel that our population does represent the “typical” intractable patient who undergoes bronchoscopy at a tertiary care center.The authors also address another issue that we raised in the article: the lack of normal pH-multichannel intraluminal impedance (MII) values in children. Given this limitation, we did not describe pH-MII values as normal or abnormal; we simply reported the means and presented the data to the reader. There are, however, published adult normal values, and we recently reported pH-MII values for a small series of pediatric control patients.1 Using our pediatric normal values as a reference, we categorized patients as those with normal and abnormal numbers of reflux events to address the concerns raised by De Boeck et al; again, we found no difference in the mean lipid-laden macrophage index (LLMI) between patients with normal or abnormal pH-MII probes (P > .05). Because many of the patients in this series were taking acid-suppression medication, we felt that the total number of reflux events, not the percentage of time the pH was <4, was the best indicator of reflux burden, because the total number of events is independent of acid suppression.2 We agree that the number of patients undergoing fundoplication is small, and we look forward to future prospective studies to address the role of pH-MII in the evaluation of preoperative patients.We feel that even with the known limitations of our data, the results in this study are very important, because they bring into question the utility of a test that is used in many institutions as a way to guide surgical therapy or more aggressive treatment. The results of this study also support other evidence in the literature about the poor relationship between reflux and the LLMI, as well as the limited value that the use of pH-probe results have in predicting successful outcome after fundoplication.3–6 We are hopeful that readers of the article will pause before they make major therapeutic decisions on the basis of the LLMI findings alone.