Chronic Cough Pearls for Primary Care

Educational Objectives

The goal of this program is to improve treatment of chronic cough. After hearing and assimilating this program, the clinician will be better able to:

1. List risk factors for chronic cough.
2. Optimize use of gabapentin in patients with chronic cough.

Summary

Chronic cough (CC): is a common issue in pulmonary clinics, often difficult to manage with limited treatment satisfaction; it is a defensive respiratory reflex controlled by neural activity in the brainstem in response to airway irritants; cough is categorized by duration; acute and subacute coughs are usually viral, while CC lasts >8 wk; chronic refractory cough persists despite treatment, and unexplained CC lacks an identifiable cause despite investigation; CC are particularly challenging to treat and often included in clinical trials

Epidemiology of CC: at any time, ≈10% people worldwide experience CC; risk factors include female sex, older age (40s-50s), smoking, angiotensin-converting enzyme (ACE) inhibitor use, and lung diseases (eg, chronic obstructive pulmonary disease [COPD], bronchiectasis, interstitial lung disease); CC significantly affects daily life, causing speech and sleep disruptions, cough syncope, stress incontinence, post-tussive vomiting, and social isolation; women experience CC at a 2:1 ratio compared with men, possibly related to higher cough reflex sensitivity, as studies show they require lower doses of capsaicin to trigger coughing

Treatable traits of CC: the understanding and treatment of CC have shifted toward identifying treatable traits, including exposure to irritants (eg, tobacco, occupational hazards, ACE inhibitors) and lung diseases (eg, COPD and bronchiectasis); type 2 airway inflammation, previously associated with asthma, is now recognized as a broader driver of CC; esophageal dysfunction, including reflux and aspiration, can contribute, as can upper airway symptoms; sleep apnea is emerging as a possible treatable trait, though evidence is limited

Modern approach to CC: involves assessing symptom burden, identifying treatable traits, and ruling out red flags; treatments are targeted rather than a broad, multidrug approach, with sequential therapeutic trials lasting 4 to 6 wk to assess effectiveness; speech therapy is now guideline-recommended as a first-line treatment before considering neuromodulators; identifying treatable traits is challenging, and predicting treatment response remains uncertain

Evaluation of CC: include confirming duration, assessing symptom severity, and identifying complications (eg, incontinence, sleep loss, social issues); sensitivity is evaluated by identifying triggers (ie, wind, laughter, temperature changes); prior treatments, adherence, and effectiveness are reviewed; specific questions focus on heartburn, nasal symptoms, recurrent sinusitis, hoarseness, shortness of breath, and wheezing; the nature of mucus production is assessed, though its characteristics are not particularly useful for diagnosis; prior specialist evaluations, weight loss, hemoptysis, and risk factors (eg, smoking, ACE inhibitor use, sleep apnea, occupational exposures) are also considered

Physical examination for CC: a focused lung examination is conducted to identify airway diseases, assessing hyperinflation, obstruction, or crackles suggestive of parenchymal lung disease; ear-nose-throat examinations are usually avoided unless symptoms warrant further evaluation, as findings, eg, nasal turbinate edema, throat erythema, lack specificity; diagnostic tests include spirometry, chest radiography, and blood eosinophil levels, with computed tomography reserved for refractory cases or red flag symptoms

Type 2 airway inflammation: is a key factor in CC, linked to asthma, cough-variant asthma, and non-asthmatic eosinophilic bronchitis; these conditions share eosinophilic airway inflammation and respond to inhaled corticosteroids; diagnosis is often confirmed by treatment response; clues include a history of atopy, allergic conditions, or respiratory obstruction in nonsmokers; blood eosinophil >300 cells/μL, sputum eosinophils >3%, and elevated exhaled nitric oxide levels (>25 ppb, with >50 ppb indicating a higher likelihood of response) can help identify treatable cases; allergy testing may provide additional insights

Management of CC: in most cases, guidelines recommend a trial of inhaled corticosteroids for all patients with CC; if a patient never tried one, prescribe medium to high-dose inhaled corticosteroids (eg, fluticasone 100 mg [Flovent 100]), 1 to 2 puffs twice daily for 4 to 6 wk; if there is no response in this period, treatment is discontinued; proper inhaler technique is important, but most corticosteroid-intolerant patients or those who had adverse effects may try a leukotriene receptor antagonist for cough variant asthma; if there are clinical asthma symptoms, treatment follows asthma guidelines; referral to allergy specialists is needed for patients with significant allergy symptoms or persistent cough despite treatment; for COPD patients with CC and blood eosinophil levels >0.3, long-acting beta agonists and corticosteroids are recommended; when cough presents with esophageal symptoms, diagnosis is usually based on heartburn and regurgitation; laryngoscopy findings (eg, erythema, pachyderma) are nonspecific and not useful in guiding therapy; advanced reflux testing includes 24-hr pH probe and impedance monitoring, usually handled through referral; barium swallow and esophagogastroduodenoscopy have poor sensitivity for reflux

Proton-pump inhibitor (PPI): guidelines advise against starting empiric PPI therapy unless there are clear reflux symptoms, as clinical trials showed no benefit for those without symptoms; for patients with reflux symptoms, PPI therapy at 20 to 40 mg twice daily is recommended for 4 to 8 wk, with longer treatment if symptoms improve but cough persists

Other options for CC: lifestyle modifications and gastrointestinal referrals are appropriate for refractory cases, and surgery is considered for patients with hiatal hernia and positive testing

Esophageal issues: can contribute to CC; aspiration is suspected based on history and evaluated with swallow studies, with treatment focusing on diet changes and speech therapy; esophageal dysmotility’s role in CC is unclear, and pro-motility agents lack evidence from clinical trials; gastrointestinal referral is an option for discussing such treatment

Postnasal drainage: is a common symptom in CC, but the idea that nasal secretions mechanically trigger cough is debated; most patients with nasal drainage or allergic rhinitis do not have cough; recent research suggests that nasal and throat inflammation may sensitize the cough reflex; evaluation includes assessing rhinitis, postnasal drainage, throat irritation, and allergies; laryngoscopy is not useful unless there are major throat symptoms; rhinoscopy and computed tomography for sinus are considered only when structural airway issues are suspected

Treatment: involves nasal rinses, nasal and oral antihistamines, nasal steroids, and leukotriene receptor antagonists; intranasal anticholinergics (eg, ipratropium) help with anterior clear drainage; allergy testing and specialist referrals are options for persistent symptoms

Obstructive sleep apnea: is commonly linked to CC, and treatment can improve symptoms; assessing and managing sleep apnea should be part of the workup

Cough hypersensitivity: is now recognized as a major driver of CC, involving a reflex pathway influenced by lung, gut, and nasal inputs; common hypersensitivity symptoms include allotussia, ie, coughing at non-irritating stimuli (eg, deep breaths, laughing, cold air) and hypertussia, ie, exaggerated response to usual irritants; guidelines recommend cough control therapy, which includes education on cough suppression techniques (eg, nasal, pursed-lip breathing); gabapentin is a well-supported pharmacologic treatment, with one trial showing effectiveness; treatment starts at 300 mg daily, increasing to 1,800 mg over 6 days; adverse effects include nausea and fatigue, but the number needed to treat is low; treatment typically lasts 6 mo, followed by withdrawal to assess recurrence; other less commonly used treatments include low-dose morphine, superior laryngeal nerve blockade, and nebulized lidocaine, though their efficacy remains uncertain; several new drugs are in development but yet to reach clinical use

Readings

Chung KF, McGarvey L, Song WJ, et al. Cough hypersensitivity and chronic cough. Nat Rev Dis Primers. 2022;8(1):45. doi:10.1038/s41572-022-00370-w; Donaldson AM. Upper airway cough syndrome. Otolaryngol Clin North Am. 2023;56(1):147-155. doi:10.1016/j.otc.2022.09.011; Visca D, Beghè B, Fabbri LM, et al. Management of chronic refractory cough in adults. Eur J Intern Med. 2020;81:15-21. doi:10.1016/j.ejim.2020.09.008; Zhang J, Perret JL, Chang AB, et al. Risk factors for chronic cough in adults: A systematic review and meta-analysis. Respirology. 2022;27(1):36-47. doi:10.1111/resp.14169.

Disclosures

For this program, members of the faculty and the planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Denstaedt was recorded at the 32nd Annual Primary Health Care of Women Conference 2024, held December 5-6, 2024, in Ann Arbor, MI, and presented by University of Michigan School of Medicine. For information about upcoming CME activities from this presenter, please visit https://umich.cloud-cme.com. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 1.00 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 1.00 CE contact hours.

Lecture ID:

IM721702

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.