Chronic cough in adults

Case scenario

A 42 year old non-smoking woman presents with a three month history of cough after a coryzal illness. The cough is worse in the morning and rarely produces sputum. She is not short of breath, and she has been taking an angiotensin converting enzyme (ACE) inhibitor for two years for hypertension.

The diagnostic dilemma

Chronic cough is somewhat arbitrarily defined as any cough with a duration of eight weeks.1 It is common in primary care. In one postal survey of 11 000 patients registered with four general practices, 14% of men and 10% of women reported coughing on more than half the days in the year.2 In practice, smokers rarely consult about their cough because they assume (usually correctly) that smoking is the cause.

The problem in diagnosis is differentiating between the common causes of chronic cough—asthma, chronic obstructive pulmonary disease, postnasal drip, gastro-oesophageal reflux disease (GORD), and drug (ACE inhibitor) induced—and not missing rare but more serious causes.

In primary care the cause of chronic cough is often uncertain, and asthma is a common diagnosis. In a study in secondary care of 78 adult non-smokers with chronic cough and a normal chest x ray, in 73 (94%) the cough was considered to be caused by one or more of the “pathogenic triad” of asthma, gastro-oesophageal reflux, and postnasal drip syndrome. In 48 patients (62%) there was more than one cause.3 Studies from specialist cough clinics found that the cause of chronic cough can be established in 89-100% of cases, making the previously popular diagnosis of “psychogenic cough” redundant.4 In smokers, chronic cough is common and can also be the presenting feature of chronic obstructive pulmonary disease or bronchogenic carcinoma. …