GERD Testing: Conduct On Therapy

Prolonged pH or reflux monitoring is neither essential to the primary evaluation or treatment of patients with suspected gastroesophageal reflux disease (GERD) who respond to therapy nor needed for patients who have endoscopydocumented erosive esophagitis that responds to antisecretory therapy. The history, endoscopic findings and clinical response to therapy provide adequate support for the diagnosis of GERD in most of these patients.

Patients who might benefit from evaluation with pH or reflux monitoring1 include those with endoscopy-negative reflux disease (ENRD); those with symptoms (heartburn and/or regurgitation) that are resistant, recurrent or incompletely responsive to standard or double-dose antisecretory therapy; those with extraesophageal symptoms, such as a cough or laryngitis; those with chest pain, globus or dyspepsia with an unclear diagnosis; those who are seeking surgical or endoscopic corrective procedures to treat their symptoms; and those who have undergone surgical procedures and are experiencing a recurrence of symptoms. Patients with Barrett’s esophagus might be considered for reflux monitoring to assess the efficacy of antisecretory therapy. This would apply particularly to those undergoing ablative therapy for dysplasia. In this article, I will make the case for on-therapy reflux monitoring.

The decision to perform reflux monitoring on or off therapy must be individualized. In my practice, this decision is based on the question needing answering. In the patient who has symptoms suspected to be due to GERD and who has been empirically treated with antisecretory therapy, the first question that needs to be answered is this: Was the original diagnosis of GERD correct? If so, the next question is why the symptoms are continuing. Is acid reflux still present? If so, is it because the proton pump inhibitor (PPI) is not optimally suppressing gastric acidity? Is weakly acidic or nonacid reflux present? Are the continued symptoms related to either acid or nonacid reflux? Ultimately all these questions can be answered with on-therapy pH monitoring.

Another way to approach these patients is to make an assessment of the pretest probability of GERD being present. I consider the pretest probability of GERD to be high if the primary symptom is heartburn and/or regurgitation, if the patient’s primary extraesophageal symptom has a substantial (more than 50 percent) but incomplete response to antisecretory therapy, or if there has been documented erosive esophagitis or Barrett’s esophagus with residual symptoms. In these patients, I perform reflux monitoring on therapy, most often with a 24-hour transnasal pH/impedance study using an intragastric and intraesophageal pH electrode. In these cases, I am looking to determine if there is continued esophageal acid exposure, normal acid exposure with a high symptom index and symptom association probability (so-called esophageal hypersensitivity), or nonacid reflux with a positive symptom association. The intragastric electrode allows me to make a qualitative assessment of acid control on the patient’s PPI. Fair to poor intragastric pH control (less than 50 percent of the monitoring period with pH less than 4) coupled with continued esophageal acid exposure makes a clear diagnosis of refractory GERD, and I will either change or increase antisecretory therapy or refer the patient for antireflux surgery.

The decision to perform reflux monitoring on or off therapy must be individualized.

There is a rare patient in whom I document poor intragastric pH control and normal esophageal acid exposure who has such a strong pretest probability of GERD (previous erosive esophagitis, Barrett’s, and so on) that I will increase (or change) medical therapy, despite what is essentially a negative study. If acid parameters are controlled but symptoms are strongly correlated with physiologic acid reflux, I will usually add a tricyclic agent to treat this hypersensitivity. This seems to improve the quality of life, albeit perhaps not the symptoms, per se.2

Surgical and endoscopic outcomes data are lacking for nonacid reflux, so clinical judgement is mandatory. I look for a clear increase above normal in the number of weakly or nonacid reflux episodes (I use more than 80 episodes), a strongly positive symptom index and symptom association probability, and regurgitation as the primary symptom, to be comfortable considering a surgical or endoscopic intervention. If I have any doubt or the symptom is extraesophageal or atypical, I will perform an off-therapy study to confirm baseline reflux before surgery. If a patient with ENT symptoms has a negative or normal on-therapy reflux monitoring study, especially when intragastric pH control is good I am comfortable deciding that the symptoms are likely not due to GERD, I will continue the work up to evaluate for a non-GERD diagnosis. It is rare in my practice for a patient with ENT symptom that presents with the above findings to have GERD identified in an off-therapy study.

Patients with Barrett’s esophagus who have undergone ablation are candidates for reflux monitoring to assess adequacy of antireflux therapy, whether medical or surgical. It is important to remember that a primary reason for recurrence of intestinal metaplasia or dysplasia is poor acid (reflux) control.3 As such, I recommend either a prolonged pH monitoring study with a telemetry (Bravo) capsule or transnasal 24-hour pH/impedance (with intragastric electrode) to assess reflux control, even in asymptomatic patients after ablation. If acid reflux persists on PPI therapy, I will optimize control by increasing the antisecretory therapy until normalized or send the patient to surgery.

There are clinical scenarios in which ontherapy reflux monitoring offers value even in patients with a low pretest probability of GERD. These include patients with extraesophageal symptoms (cough, voice abnormalities) or chest pain, dyspepsia, dysphagia, or other atypical symptoms attributed to GERD but who have normal EGDs and poor responses (less than 50 percent) or no responses to optimized (before breakfast and dinner) PPI therapy. A negative 24-hour pH/impedance study (normal esophageal acid exposure, negative symptom association, normal weakly acid reflux numbers and excellent intragastric pH control) allows me to comfortably conclude that the residual symptoms are not reflux related. These patients should have the original diagnosis of GERD reevaluated, perhaps with an off-therapy study.

Overall, the decision to perform reflux monitoring on or off therapy must be individualized. However, the patient who has symptoms that are suspected to be due to GERD, who is not responding sufficiently to optimized antisecretory therapy and who has a normal EGD will be well served with a wellperformed combined transnasal impedance/pH study on therapy.


1.Katz, P.O., Gerson, L.B., Vela, M.F. Diagnosis and Management of Gastroesophageal Reflux Disease. Am J Gastroenterol. 2013;108:308–328.
2.Limsrivilai, J., Charatcharoenwitthaya, P., Pausawasdi, N. Imipramine for Treatment of Esophageal Hypersensitivity and Functional Heartburn: A Randomized Placebo-Controlled Trial. Am J Gastroenterol. 2016;111(2):217–24.
3.Krishnan, K., Pandolfino, J.E., Kahrilas, P.J. Increased Risk for Persistent Intestinal Metaplasia in Patients With Barrett’s Esophagus and Uncontrolled Reflux Exposure Before Radiofrequency Ablation. Gastroenterology. 2012;143(3):576–81.

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