Cough
David Picker
Praveen R. Chenna
General Principles
Cough is a common symptom and a substantial driver of outpatient care visits.
Cough accounts for nearly 30 million physician visits per year. Estimated costs for treatment may reach $1 billion annually, not including the cost of diagnostic testing and complications such as headache, hoarseness, urinary incontinence, musculoskeletal pain, and exhaustion.
Due to the adverse effects on the quality of patients’ lives, a systematic approach is necessary for the diagnosis and management of cough in the adult patient.
Classification
Cough is classified based on the duration of symptoms, which can help provide a framework for diagnosis.1
Acute cough is defined as <3 weeks.
Subacute cough is defined as >3 weeks, and <8 weeks.
Chronic cough is defined as >8 weeks.
Acute Cough
Acute cough can be divided into three main categories; infectious, exacerbation of underlying disease process, and exposure-related.
Infectious
Viral infections of the upper respiratory tract are the most common cause of acute cough. Rhinovirus, coronavirus, and respiratory syncytial virus are the pathogens most frequently associated with common cold symptoms. Less frequent causes include influenza, parainfluenza, and adenovirus.
Clinical features of the common cold include rhinorrhea, sneezing, irritation of the throat, lacrimation, and nasal obstruction. Fever may or may not be a presenting symptom. Coughing usually presents on day 4 or 5 after infection.
Chest radiograph is usually negative and therefore of low yield in the general population. However, certain exceptions should be considered in the elderly and immunocompromised to rule out potential pneumonia, or other insidious infection.
Viral or bacterial rhinosinusitis can also result in postnasal drainage and acute cough.
Viral rhinosinusitis may be difficult to distinguish from bacterial sinusitis.
Viral rhinosinusitis can be symptomatically managed with antihistamines and nasal decongestants.
Bordetella pertussis infection is common cause of acute cough in adults. Symptoms may include a barking cough and post-tussive emesis. Diagnosis may be confirmed by sputum culture or B. pertussis PCR testing.
Exacerbation of underlying disease process
Allergic rhinitis is an IgE-mediated syndrome characterized by paroxysms of sneezing, nasal congestion, and irritation of the eyes and nose.
Postnasal drainage is probably the mechanism leading to acute exacerbation and may be a prominent symptom when cough is severe.
Symptoms are often improved by using nonsedating antihistamines and avoiding offending allergens.
COPD exacerbation may result from smoking, air pollutants, allergens, and infections.
Streptococcus pneumoniae, Haemophilus influenza, and Moraxella catarrhalis are among the most common bacterial pathogens isolated in COPD exacerbations.
Antibiotics may be prescribed if the acute cough is accompanied by worsening shortness of breath, increased oxygen requirements, increased sputum production, or change in the character of sputum.
Exposure
Occupation or environmental exposures may also be contributors to cough. A thorough history, including workplace exposures, household exposures (including pets or new carpeting), and change in medications will help to pinpoint the diagnosis.
Chronic Cough
Cough >3 weeks is often attributable to one of a handful of diagnoses in nonsmokers. These include upper airway cough syndrome (UACS) which was previously referred to as postnasal drip syndrome, asthma, and gastroesophageal reflux disease (GERD).2
Upper airway cough syndrome
The most common cause of persistent cough in nonsmokers.
Symptoms may include nasal discharge, frequent throat clearing, and a sensation of nasal discharge dripping into the back of the throat.
Physical examination may show secretions in the nasopharynx, and presence of cobblestoning.
However, postnasal drip may be silent, leaving the practitioner with nonspecific symptoms to help guide treatment.
Therefore, when there is a lack of alternative cause of a patient’s cough, empiric therapy for postnasal drip should be attempted before other extensive workups for alternate cough etiologies.
Asthma
The leading cause of chronic cough in children and second most common cause of chronic cough in the adult population.
The clinical spectrum of symptoms includes recurrent episodic wheezing, chest tightness, breathlessness, and cough, particularly at nighttime and/or in the early morning.
Cough-variant asthma will often present with cough and may progress to encompass other common asthma symptoms.
Gastroesophageal reflux
GERD is the third most common cause of chronic cough.
Symptoms include heartburn or a sour taste in the mouth, but some patients may also lack these symptoms.
Prolonged esophageal pH monitoring is generally considered the gold standard for confirmation of GERD.
Chronic bronchitis
The most common cause of chronic cough in smokers.
Defined as cough productive of sputum ≥3 month’s duration in at least 2 consecutive years in the absence of other lung diseases that may cause cough.
Usually found with extensive smoking history, often >1 pack per day for more than 20 years.
An acute change of cough, or caliber of sputum is what may lead to initial presentation. It is important to remember these patients are at higher risk of developing neoplasm secondary to underlying smoking history.
Angiotensin-converting enzyme inhibitors
Angiotensin-converting enzyme (ACE) inhibitors have been associated with cough in up to 15% of patients taking this class of medication.
Usually begins within 1 week of starting treatment but can be seen up to 6 months later.
Patients often report a “tickling” or “scratching” sensation in their throat, and the symptoms usually resolve within 1 week of discontinuing therapy (although it may take longer in some patients).
Mechanism is not entirely clear, but it is believed that accumulation of bradykinin may stimulate afferent nerve fibers in the airway. This is supported by data in patients who take angiotensin II receptor blockers (this class of medication does not affect kinin levels) and are not at increased risk of cough.
Bronchiectasis
Bronchiectasis occurs less frequently.
Some studies show bronchiectasis is responsible for chronic cough in ∼4% of patients in the United States.
Bronchiectasis is the result of repeated damage from chronic infections and airway inflammation in the bronchial tree that leads to irreversible dilatation of the affected airways. This anatomical alteration can lead to easily collapsible airways, poor mucus excretion, and chronic infection.
Most patients will produce chronic mucopurulent sputum at baseline that becomes more purulent during acute infectious processes.
Other etiologies of chronic cough
Eosinophilic bronchitis is increasingly being recognized as a cause of chronic cough.
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