How should chronic cough be assessed and managed?

Chronic cough—defined as cough lasting eight weeks or longer—affects approximately 16% of Canadian adults 45 to 85 years of age. This condition is often associated with physical, social and psychological impairments. Currently, no product is licensed for the treatment of chronic cough in Canada. A recent Canadian review article highlights the investigations, management and current and future treatment options for chronic cough. Most cases are due to a benign cause; however, chronic cough can signify a serious underlying condition. Therefore, it is important to follow a systematic approach to the diagnosis and management of chronic cough. Assessment of chronic cough should include a detailed history and examination to identify potential causes and triggers. Factors associated with chronic cough include angiotensin-converting enzyme inhibitor (ACEI) use, smoking, asthma, non-asthmatic eosinophilic bronchitis, gastroesophageal reflux disease (GERD) and upper airways cough syndrome. Red flags for more serious underlying disease include hemoptysis, weights loss and fever. Read: New guideline recommends against routine screening for esophageal adenocarcinoma in patients with chronic GERD Labs tests that might be useful in cough assessment include a chest x-ray, spirometry, complete blood count and tests to assess airway hyperresponsiveness. Subjective questionnaires can be used to assess the impact and severity of chronic cough. Treatment Chronic cough can be challenging to treat, since over-the-counter therapies are generally ineffective. Management should start with smoking cessation, including e-cigarettes and cannabis, treatment of any underlying infections, exclusion of malignancy and replacement of ACEIs. If an underlying condition associated with cough is detected, treatment targeting this condition may lead to complete or partial resolution of the cough. An inhaled corticosteroid can be tried for six to eight weeks in patients with chronic cough and confirmed asthma. For patients with GERD, lifestyle changes such as avoiding foods that exacerbate acidity, avoiding heavy meals before sleep and raising the head of the bed are important first steps. Elimination or reduction of caffeinated beverages (e.g., coffee, tea, sodas), alcohol, chocolate and citrus products is also recommended for GERD-related chronic cough. A two-month trial of an antacid (30 mins before meals), a proton pump inhibitor or H2 antagonist should only be undertaken in patients with objective evidence of reflux. Discontinuation of the ACEI is the only effective treatment of ACEI-induced cough; improvement is generally seen within four to eight weeks. Read: Cheap antidepressant fluvoxamine shows promise treating early COVID-19: study Refractory or unexplained cough Cough is considered to be “refractory chronic cough” in cases where treatment of an associated condition does not lead to full resolution of the cough, In cases where no underlying disease is identified, the cough is described as “unexplained chronic cough.” Dextromethorphan has not been studied for refractory or unexplained chronic cough; therefore, it is not recommended. Possible options include speech and language therapy, and neuromodulator treatments (e.g., off-label use of a low-dose opioid, gabapentin or pregabalin). All three neuromodulator therapies have demonstrated an improvement in symptoms and quality of life in randomized controlled trials, but the trials have been small, and the doses used were associated with high rates of adverse events (e.g., dizziness, drowsiness, unsteadiness, fatigue). Low-dose opioid therapy (e.g., 5–10 mg slow- or modified-release morphine twice daily) may be effective. If a response is seen, it usually occurs within three to seven days. If the patient experiences benefit, the dose should be titrated to minimize side effects such as constipation, drowsiness and sedation. Gabapentin has been studied beginning with 300 mg on the first day and increasing by 300 mg on each subsequent day until a maximum of 1800 mg (600 mg three times daily) is reached. Pregabalin has been investigated in combination with speech therapy. The starting dose was 75 mg, increasing every two days to a maximum of 300 mg/day (75 mg morning, 75 midday, 150 mg evening). Future therapies New peripherally- and centrally-acting drugs are currently under study for refractory or persistent chronic cough. Most promising are drugs such as gefapixant and eliapixant, which target purinergic P2X3 receptors on vagal afferent nerves. These and other agents under study are discussed further in the article. Reference 1. Satiahttps I, Wahaba M, Kumhttps E, et al. Chronic cough: investigations, management, current and future treatments. Can J Resp Crit Care Sleep Med 2021; published online October 26, 2021. (accessed December 6, 2021).

How should chronic cough be assessed and managed?

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