Prolonged cough and chronic cough

Abstract

Prolonged cough is defined as a cough lasting longer than 3 weeks as the only symptom and whose cause is not apparent by physical examination and routine testing such as CXR and spirometry. This also includes causes of chronic cough described below, but with symptoms lasting less than 8 weeks. Thus, the causes of prolonged cough and chronic cough may overlap. Chronic cough is defined as a cough lasting longer than 8 weeks as the only symptom and whose cause is not apparent by physical examination and routine testing such as CXR and spirometry. Diagnosis and treatment is successful in over 95% of patients with chronic cough. Prolonged and chronic coughs are often triggered by the common cold, but antibiotic treatment for infection is usually ineffective except in sinusitis and sinobronchial syndrome (SBS). Figure 4.1 outlines the evaluation of prolonged and chronic coughs, and Table 4.1 lists the causes and underlying disorders. In Japan, the three most common causes of chronic cough are SBS (productive cough), cough-variant asthma (non-productive cough) and atopic cough (non-productive cough).1 Prolonged cough may develop after a viral upper respiratory infection (referred to as a ‘post-infectious (non-productive) cough’). Although less common, coughs due to gastro-esophageal reflux (GER) or ACE inhibitors and psychogenic or habitual cough must also be considered. Outline of prolonged and chronic cough in adult. ACE, angiotensin converting enzyme. Coughs include productive cough, which is a physiological cough to expectorate sputum, and non-productive cough, which is primarily a pathological cough. In productive coughs, diagnosis and treatment is focused on airway hypersecretion, whereas in non-productive coughs, diagnosis and treatment is focused on the cough itself. At least two underlying mechanisms are involved in non-productive coughs. One is increased airway cough reflex sensitivity seen in atopic cough and coughing due to GER and ACE inhibitors. The other is coughing triggered by bronchial smooth muscle contraction, which is characteristic in cough-variant asthma.