People with chronic cough can experience significant quality of life impairment. Cough is a fundamental protective reflex that can become disordered and lead to a persistent symptom complex that limits quality of life. The assessment should consider whether it is a manifestation of a significant underlying disease such as pneumonia, cardiac failure or an exacerbation of asthma or COPD.
Alarm symptoms that suggest a serious underlying disease are coughing up blood, a significant tobacco smoking history, a smoker older than 45 years with a new cough, altered cough, cough with a voice disturbance, shortness of breath especially at rest or night, substantial mucus production, hoarseness, fever, weight loss and an abnormal chest x-ray.
Acute cough (less than 3 weeks), the most probable diagnosis are respiratory tract infection, asthma or COPD exacerbation and pneumonia.
Subacute cough (3-8 weeks), most likely can be postinfectious cough syndrome, asthma/COPD exacerbation, bronchitis, upper airway cough syndrome.
Chronic cough (more than 8 weeks), the most probable diagnosis are asthma, acid reflux, upper airway cough syndrome and bronchitis.
Here we discuss causes of chronic cough
- Angiotensin-converting enzyme inhibitor treatment (ACE-I) 20% of patients treated with these antihypertensive medications can develop chronic cough. This may be higher in Asian patients.
- Post infectious cough syndrome, these are patients that report their cough developed after a respiratory tract infection. A dry and irritating cough is present. Pertussis and influenza are commonly found, the mechanism is a heightened cough reflex sensitivity following a viral infection.
- Upper airway cough syndrome, this was previously known as postnasal drip syndrome, other terms used are rhinosinusitis, sinobrachial syndrome or atopic cough.
- Eosinophilic bronchitis can occur as part of asthma or as a separate condition causing chronic cough without asthma. This responds well to steroid therapy which often completely resolves the cough.
- Obstructive sleep apnea (OSA) can be improved by nasal continuous positive airway pressure therapy. OSA and chronic cough occurs between 33%-68% of the time. Nocturnal cough is usually present.
- Asthma is the most common disease associated with chronic cough. Typical symptoms are cough, wheeze, chest tightness and shortness of breath that responds to albuterol. Cough variant asthma can have cough as the only symptom.
- Gastroesophageal reflux disease can cause cough when stomach acid activates the lower esophageal sensory nerves. Antireflux treatment with proton pump inhibitors and lifestyle/diet measures can help.
- Vocal cord dysfunction is when the vocal cords close during inspiration, chronic cough can occur in up to 50% of patients. This can be diagnosed by laryngoscopy. Speech therapy may be beneficial.
Chronic cough includes an assessment and management of the underlying cause. In many as 40% of the patients, the cough remains unexplained and persistent. A number of treatment options are available to patients such as gabapentin, pregablin, amitriptyline and morphine. There are also a number of clinical trials available in the management of refractory chronic cough. Overall, clinical management is directed at identifying and treating cough stimuli (exposures, diseases) and managing the components of cough hypersensitivity. This approach leads to a reduction in cough and improved quality of life for those who have chronic cough.