Chronic Cough Diagnosis

Most Common Causes

In nonsmoking adults with chronic cough (>8 weeks) and normal chest X-ray who are not taking ACE inhibitors, the American College of Chest Physicians recommends focusing the diagnostic approach on upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD), as these three conditions account for 92-100% of cases, either alone or in combination 1, 2, 3
Upper airway cough syndrome (UACS) is the most common single cause of chronic cough, and can be completely "silent" with no nasal symptoms, due to rhinosinusitis, allergic rhinitis, vasomotor rhinitis, or other rhinosinus conditions 1, 2, 3
Asthma is the second most common cause of chronic cough, and may present as "cough variant asthma" with cough as the only symptom, with no wheezing or dyspnea required for diagnosis 1, 2, 3
Gastroesophageal reflux disease (GERD) is the third most common cause of chronic cough, and can be "silent GERD" without heartburn or regurgitation, with cough as the sole manifestation 1, 2, 3

The American College of Chest Physicians recommends that the character, timing, or productivity of the cough should not be used to rule in or rule out any diagnosis, as it has no diagnostic value 1, 2
Up to 25% of patients have multiple contributing diagnoses, and all three common causes (UACS, asthma, GERD) must be considered in every patient regardless of symptoms 1, 2
If cough persists after treating common causes, or if red flags are present (fever, weight loss, hemoptysis, recurrent pneumonia), consider uncommon causes and proceed to chest CT scan and bronchoscopy if indicated 5, 7
In peritoneal dialysis patients, there is an increased prevalence of GERD, pulmonary edema, asthma exacerbated by beta-blockers, and infection, and in immunocompromised patients, the same initial algorithm should be used but the differential diagnosis should be expanded based on the type and severity of the immune defect 5, 7

ACE inhibitor-induced cough can occur anytime within the first year of therapy, and the median resolution time is 26 days after discontinuation, with a range of a few days to 2 weeks 6
Nonasthmatic eosinophilic bronchitis (NAEB) is an increasingly recognized important cause of chronic cough, and should be considered early in the evaluation, as it responds predictably to inhaled corticosteroids 1, 2, 4