Update on Chronic Cough

It is not uncommon for a pediatric gastroenterologist to see a patient with a chronic cough due to concerns about potential gastroesophageal reflux disease (GERD).  As such, a recent clinical practice article (JA Smith, A Woodcock. NEJM 2016; 375: 1544-51) by lung specialists was of interest, even though this article was not targeted to the pediatric population.

Key points:

  • The authors define a chronic cough as lasting more than 8 weeks and note that it common with respiratory conditions (eg. chronic obstructive pulmonary disease, asthma, and bronchiectasis) and some non-respiratory conditions (eg. gastroesophageal reflux and rhinosinusitis).  Medications, particularly ACE inhibitors, can trigger a chronic cough as well.
  • Steps in evaluation: 1. H&P, CXR, spirometry. 2. Consider metacholine challenge, ENT evaluation, consider empiric treatment (eg. inhaled glucocorticoids, PPI), and consider GERD evaluation. 3. High-resolution CT and bronchoscopy.
  • For many patients, there is likely to be an abnormality in neuronal pathways controlling cough and the term “cough hypersensitivity syndrome” has been coined.  Figure 2 (below) illustrates the neuronal pathways.
  • For refractory patients, potential therapies would include low-dose morphine, gabapentin or pregabalin, and speech language therapy.

screen-shot-2016-10-26-at-8-24-57-pm

GERD:

  • Guidelines “suggest a trial of treatment with acid-suppression therapy” (eg. twice-daily PPIs for up to 3 months).
  • “Most randomized, controlled trials of reflux treatment for cough have not shown a significant improvement in association with this type of treatment.”
  • Subgroups of patients with heartburn, regurgitation, or excessive acid reflux on esophageal pH monitoring “appeared marginally more likely to have a response to PPI treatment.”  pH or impedance tests “are poorly predictive of a response of cough to acid suppression.”

My take: In the absence of clinical reflux, reflux therapy is unlikely to help with chronic cough.  However, in patients with an adequate workup, an empiric course of a PPI is likely more preferable than empiric morphine or gabapentin.

Related blog posts:

 

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