REVIEW SERIES Cough ? 1: Chronic cough in adults

Correspondence to: Professor A H Morice, Academic Department of Medicine, Respiratory Medicine, University of Hull, Castle Hill Hospital, Castle Road, Cottingham HU16 5JQ, UK; [email protected] . . . . . . . . . . . . . . . . . . . . . . . C hronic cough is a common diagnostic and therapeutic problem. The exact prevalence has proved difficult to estimate and recurrent cough is reported by 3–40% of the population. The results of questionnaire surveys such as these are clearly influenced by the population studied and the question posed. In a postal and telephone survey of over 11 000 patients from four general practices in south east England, cough was reported every day or on over half of the days of the year by 14% of men and 10% of women. A survey of 18 277 subjects aged 20–48 years from 16 countries worldwide reported nocturnal cough in 30%, productive cough in 10%, and non-productive cough in 10%. In this study the very high prevalence of nocturnal cough arose because a positive response to the question ‘‘Have you been woken by an attack of coughing at any time in the last 12 months?’’ was taken as indicating the symptom. However, since acute cough—by far the commonest symptom for which medical advice is sought— could also lead to a positive response, significant nocturnal cough was probably overestimated in this study. Whatever the failings of individual surveys, chronic cough is clearly a very common symptom which, although associated with considerable morbidity, goes largely unheeded. Unsurprisingly, cigarette smoking had a dose related influence on the prevalence of productive cough. In clinical practice, however, smokers readily ascribe their cough to tobacco and rarely seek medical advice specifically to combat this. As a consequence, the incidence of smoking related cough presenting as an isolated symptom in secondary care is low. The reasons why patients seek advice regarding chronic cough are not fully understood, but may be related to worry about the cough. Often, cough related morbidity—in terms of sleep disturbance (either of the patient or their relatives), urinary incontinence in women, or syncope—drives the patient to consult. Indeed, chronic cough has been shown to be associated with a marked deterioration in quality of life which returns to normal on successful treatment. In population surveys, men have reported cough more frequently. 10 11 However, most patients referred to specialist cough clinics are women (table 1). This paradox may be explained by differences in smoking habit, but women also appear to have an intrinsically heightened cough response. Inhalation cough challenge is augmented in both healthy female volunteers and female patients with chronic cough. A higher frequency of ACE inhibitor induced cough is also found in women, suggesting that any sex related difference is unlikely to be due to augmented deposition of tussive stimuli in women. A hormonal influence is inferred by the observation that cough reflex sensitivity is similar in boys and girls, but the reason for the marked sex difference in adults remains obscure. Duration is important in determining the possible aetiology of cough. Classically, cough lasting less than 3 weeks has been considered as acute and that of more than 3 weeks duration has been defined as chronic. In recent years there has been a tendency to redefine chronic cough as cough lasting more than 8 weeks and, for further clarification, the term ‘‘subacute cough’’ was proposed to describe cough lasting 3–8 weeks. While these definitions remain arbitrary, the concept of chronic cough remains clinically important. In this review we will describe the assessment and management of patients with chronic cough.