Burden of chronic cough in the UK: results from the 2018 National Health and Wellness Survey

Discussion

In a representative sample of 15 000 adult UK residents, 4.8% reported chronic cough lasting ≥8 weeks during the last 12 months, with a lifetime prevalence of 6.1%. When projected to the general population, we estimate a 12-month prevalence of 4.9% and lifetime prevalence of 6.2% for chronic cough among UK adults. Chronic cough was more prevalent in women than men and in respondents ≥50 years old. Compared to matched controls without chronic cough, respondents with chronic cough were more likely to be obese and to be smokers. Adults with chronic cough reported poorer mental and physical health and QoL, with significantly higher rates of moderate/severe anxiety, mild to severe depression and sleep disturbances. Adults with chronic cough were more likely to visit emergency, general, and specialist respiratory or gastroenterology healthcare providers. Chronic cough was associated with impairment of daily activities and with reduced work productivity among employed respondents.

We present, to our knowledge, the first UK general population prevalence estimate for adult chronic cough that uses the definition of daily cough for at least 8 weeks. Our 12-month prevalence estimate of 4.9% is similar to the 5% prevalence estimate for daily cough during the prior 2 months that was reported in a previous English study, although respondents in the study were selected from a Helicobacter pylori screening and treatment cohort rather than a general population sample and participation was restricted to respondents aged 50–59 years [7]. A 2021 database study including records of adults 18 years and older from a northwest London dataset identified chronic cough in 2% of the population [30]. In this study, patients with chronic cough were defined as those with two or more recorded consultations coded as “cough-related” persisting for at least 8 weeks. These estimates may under-report the prevalence of chronic cough in the UK as they are limited by generalisability and potential coding omissions and errors, noting also that free text chart entries were not extracted into the dataset and therefore could not be analysed. The previously mentioned 2015 meta-analysis reported a global overall prevalence of 9.6% and a European prevalence of 12.7%; however, the 90 studies included in the meta-analysis used a total of 19 different definitions of chronic cough, largely relying on older clinical guidelines that defined chronic cough as daily cough for ≥3 months [5]. Only three of the included studies in the meta-analysis used the current 8-week definition, with the English study described above being the only one of these three studies to report on a European population. Further, only 16 of the 90 studies included in the meta-analysis assessed chronic cough as their primary outcome [5]. In addition to our prevalence estimates, we identified associations between chronic cough prevalence and sex, age, smoking history and obesity, in line with similar findings from previous studies [7, 9, 31].

Our age-, sex- and comorbidity-based matching strategy provides a unique comparison between people with and without chronic cough using a representative sample of the general UK population, allowing a more accurate characterisation of the burden of chronic cough in the UK. Previous studies have generally reported on the patient burden of chronic cough in specialised samples. For example, a study of a small group of UK cough clinic patients (n=67 matched to n=22 controls) identified associations between chronic cough and anxiety, depression and fatigue [16], and an analysis of a group of specialist-diagnosed patients from the USA matched to controls without chronic cough provided evidence for an association between chronic cough and obesity as well as higher HCRU [9].

Chronic cough has impacts on both physical and mental health [32, 33] with the impact on QoL reported to be similar to that of other respiratory diseases including COPD, asthma and bronchiectasis [34]. A number of studies have described the burden of chronic cough in patients who were not matched to controls without chronic cough, identifying high rates of sleep disturbances, anxiety, depression, HCRU, and activity and work productivity impairments [8, 13–15, 17]. People with chronic cough have been reported to have higher rates of anxiety and somatisation compared to established normal ranges [17]. The current study adds to this body of literature, providing a detailed characterisation of the overall burden of chronic cough in the UK population.

The economic burden of chronic cough has not been studied extensively. However, chronic cough is likely to have a significant economic burden as it has been reported to impact job productivity [1, 35]. A Finnish survey of public service employees in two towns in Finland found that cough caused a substantial socioeconomic burden by increasing the probability of a doctor's visit and sick leave days with 16.0% of respondents with chronic cough taking 7 or more sick days and 20.3% having three or more doctor's visits due to cough within a 12-month period [36]. In a large general population sample of adults aged 20–44 years from Sweden, Norway, Denmark, Iceland and Estonia, respondents with broadly defined chronic cough (i.e., those who answered “yes” to the question “Have you in recent years been troubled by a protracted cough?”) were significantly more likely to have taken >7 days sick leave in the preceding year and to have lower self-reported work ability scores [18]. These results are in line with our finding that UK respondents with chronic cough have significantly higher rates of absenteeism, presenteeism and lower overall work productivity than matched controls, thus continuing to strengthen the evidence that chronic cough has an economic impact. Further, the 2021 North West London dataset study described previously reported that there was an increase in the number of investigations performed in the 12 months following a chronic cough diagnosis [30]. Primary care chest radiographs and spirometry increased by 49% and 34%, respectively, in the year after the chronic cough diagnosis [30]. This increase was accompanied by an increase in chronic cough-associated healthcare utilisation costs with annual per patient per year costs increasing by 62.85% after the chronic cough diagnosis [30].

Despite the strengths of this study, there are some study limitations. Our study participants were general population respondents to the 2018 UK NHWS, which uses quota sampling to mimic the age and sex distributions of the UK general population, ensuring that the country-wide sample is broadly representative of those features. However, employment status and income are not used as recruitment targets; thus there may be differences between employment and income levels observed in our study relative to the general UK population. Furthermore, the NHWS is a cross-sectional survey that does not allow causal conclusions to be drawn. Our analyses include many self-reported measures recalled over the prior calendar year, without physician confirmation of diagnosis or diagnostic testing; these limitations might introduce recall and self-presentation biases. Survey questions focused on more recent timeframes (e.g., previous week, 2 weeks, or month) to reduce recall bias, and “don't know” and “refuse to answer” options were included for sensitive questions to reduce self-presentation bias. Further, we did not have a specific way to capture productive cough and, therefore, we could not further stratify our results by productive and non-productive cough. Lastly, our analysis did not exclude current smokers, a factor related to an increased prevalence of chronic cough in the present study. Comparisons of our study with others should take into consideration this feature of our design, along with our 8-week definition of chronic cough.

In conclusion, we estimate that 4.9% of UK adults have experienced chronic cough in the preceding 12 months, and 6.2% during their lifetime. The prevalence of chronic cough is higher among older adults and in those with smoking history; chronic cough respondents tended to be more obese than matched controls. Adults with chronic cough report lower QoL and greater work productivity losses than those without chronic cough, and use more general, specialist respiratory and gastroenterology, and emergency HCRU. Our findings provide a detailed characterisation of the prevalence and burden of chronic cough in the UK that will inform future efforts to raise awareness, promote management strategies, develop effective treatments, and consider the educational and support needs of patients with chronic cough.