Sabine Roman, MD, PhD, associate professor of gastroenterology and physiology at Lyon University Hospital in France, took the floor at the United European Gastroenterology Week to discuss the link between a chronic cough and gastroesophageal reflux disease (GERD). During a session on extraesophageal symptoms, Roman relayed two key messages: In patients with a chronic cough, reflux absolutely must be documented, and proton pump inhibitors (PPIs) must only be prescribed when a diagnosis of GERD has been made.
Overestimated Cause
Chronic cough is a widespread problem with a prevalence of between 9% and 33%, according to clinical studies. The root causes of this cough are varied; they're mainly related to the respiratory system (eg, asthma, chronic obstructive pulmonary disease, respiratory infections, or smoking) and the ear, nose, and throat field (eg, postnasal drip). What's more, taking certain medicines, notably angiotensin-converting enzyme inhibitors, can also be at the root of this condition.
GERD is also a possible cause of a chronic cough but one that is likely overestimated. A 2023 Spanish study provides evidence of this; GERD was suspected to be linked to cough in 46% of patients (compared with 32% for asthma and 15% for postnasal drip).
The treatments most commonly prescribed include PPIs (79.6%) and respiratory medicines (87.8%). Note that antibiotics are administered empirically to 28.6% of patients. For Roman, "the blame for a chronic cough is too often assigned to GERD, especially considering that in this study, only 43% of patients had seen a gastroenterologist, 27% had an endoscopy, and 24% had undergone esophageal pH monitoring."
Added to this observation is the difficulty of establishing a causal link between a cough and GERD when the latter is present, even when the patient has had a diagnosis of GERD. Of course, a link between the two does not necessarily imply a cause–effect relationship, especially given that studies have shown that a cough itself can induce GERD. Studies using automatic cough detection to count cough events have shown that GERD certainly preceded a cough in 48% of patients, but in 56% of cases, it was the cough that came before the GERD. What's more, both mechanisms were present in one third of patients.
Prescribing PPIs Effectively
PPIs are commonly prescribed as a test treatment. However, their efficacy is in no way proof of the existence of underlying GERD. In reality, all placebo-controlled studies have shown that in cases where no prior diagnosis of GERD has been made, PPIs have no superior efficacy.
If reflux has been proven, then the improvement provided by PPIs, compared with placebo, is between 12% and 35%. Therefore, it is essential that the presence of GERD be demonstrated, particularly if the patient has no characteristic symptoms of GERD, such as heartburn and acid reflux.
Response factors to PPIs were evaluated in 178 Italian patients with a chronic cough who presented with suspected GERD. Of those, 45% responded to treatment. It has been shown that typical symptoms, severe esophagitis (grade C/D), abnormal acid exposure, and low levels of nocturnal baseline impedance were independent factors of response to treatment.
In conclusion, patients with a chronic cough must be comprehensively tested for GERD before a long-term prescription of PPIs can be considered.
Cough Reflex Threshold
Various studies have also revealed that patients with GERD and presenting with a chronic cough have an increased sensitivity to the cough reflex. This hypersensitivity to the cough reflex has inspired several trials involving gabapentin and baclofen. A randomized controlled trial found the two treatments to be equally effective, achieving improvement of around 50%.
Lesogaberan, a new GABA(B) receptor agonist acting on the peripheral nervous system which is better tolerated than baclofen, a drug belonging to the same therapeutic class, showed a 26% benefit over placebo, but it was not statistically significant; lesogaberan has not been developed further.
Anti-reflux surgery is an option. A 2021 meta-analysis revealed that 84% of patients enrolled in these studies saw an improvement in their symptoms. However, these results must be regarded with caution because none of these studies were controlled, most of them were retrospective with very heterogeneous patient populations, and the data obtained on postoperative reflux control were often found to be lacking.
A retrospective study showed that among the factors for nonresponse or recurrence of symptoms after anti-reflux surgery, lack of response to medical treatment and extraesophageal symptoms such as a cough were significant factors. Consequently, potential candidates for surgery must be rigorously screened before being considered for such a procedure.
The recent recommendations for good practice published by the American Gastroenterological Association also insist that lack of response to medical treatment is a major factor for failure of surgical treatment.
In sum, patients with a chronic cough can be prescribed PPIs as first-line treatment if they have typical symptoms of GERD. In the event of treatment failure or isolated cough without typical symptoms, tests to confirm or rule out GERD are essential (such as endoscopy, esophageal pH monitoring, or impedance-pH monitoring).
This article was translated from the Medscape French edition.
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