How best to measure cough clinically

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Highlights

  • Cough endpoints include severity, frequency, intensity, urge and quality of life.

  • Cough frequency monitoring is emerging as a primary outcome measure for antitussive medications.

  • The most important endpoint from a patients’ perspective is quality of life.

  • Cough reflex sensitivity should be used to evaluate mechanisms of therapy, rather efficacy.

It is possible to measure cough by assessing its severity, frequency, intensity, associated urge and its impact on quality of life. Cough severity can simply be assessed with a Visual Analogue Scale. Cough frequency can be assessed objectively with cough frequency monitors. Validated cough monitors include the Leicester Cough Monitor and the VitaloJAK. Cough reflex sensitivity measurement is better used to investigate the mechanisms of action of antitussive medications, rather than assessing efficacy. Health-Related Quality of Life measures are available to assess the impact of cough; they include the validated Leicester Cough Questionnaire and Cough-specific Quality of Life Questionnaire for adult patients. It is best to assess cough with a combination of subjective and objective tools, to capture its wide-ranging impact.

Introduction

Cough is one of the most common reasons why patients consult their doctor. Cough can lead to significant physical, psychological and social morbidity [1]. Adverse symptoms associated with cough such as incontinence and pain, absence from work and social embarrassment are frequent [2]. Cough should be measured and quantified when objective verification is necessary and for assessing the efficacy of therapy [3]. The formal assessment of cough is mostly limited to the research setting, since in the clinic most physicians simply ask patients about the severity of their cough. However, validated subjective and objective tools are available, such as cough frequency monitors and Health-Related Quality of Life (HRQOL) questionnaires [4]. This review will focus on recent developments in the assessment of adult patients with cough.

Section snippets

Which tool to assess cough?

The choice depends on the context of the setting. Several components of cough can be assessed, which include severity, frequency, intensity, urge and its impact (HRQOL), see Figure 1. The most widely used tools assess severity, frequency and HRQOL. In the clinic, when the doctor asks the patient about their cough, the impact of cough on the individual can easily be overlooked. The 0–10 cough severity rating is one simple measure that could be used in a busy clinic. The clinician asks the

Cough severity

Cough severity can be assessed with the cough VAS, the Cough Severity Score (CSS) and the Cough Severity Diary (CSD). Cough VAS is a brief and simple measure of cough severity [9]. It is important to ensure that the scale is 100 mm in length, especially when electronic scales are used. The scale must be closed at both ends with perpendicular lines, and the wording at the extremes of the scale must be stated outside the scale. An example of a cough VAS is given in Figure 2. VAS has not been

Quality of Life Questionnaires

There are two HRQOL questionnaires widely used in the assessment of adult patients with cough. The Leicester Cough Questionnaire (LCQ) is a nineteen-item questionnaire that comprises of three health domains; physical, psychological and social [13]. It has been evaluated in patients with chronic and acute cough, post-infectious subacute cough, bronchiectasis and chronic obstructive pulmonary disease (COPD) [10•, 14, 15, 16, 17•]. The LCQ has been well validated. Its internal consistency,

Objective cough frequency monitoring

For the objective assessment of cough frequency, there are two tools currently in use in clinical trials, the Leicester Cough Monitor (LCM) and the VitaloJAK. They are both ambulatory and measure cough in the patient's own environment. The LCM is an automated monitor [25, 26, 27]. It consists of an MP3 recording device and a lapel microphone. It can record up to four days continuously and it is practical for large-scale, multi-centre studies due to its automated capability. The cough detection

Cough reflex sensitivity challenge tests

The sensitivity of the cough reflex can be evaluated by numerous tussive agents, most commonly capsaicin and citric acid. Other tussive agents available include fog, low chloride solutions, bradykinin, prostaglandin E2, mannitol and cinnamaldehyde. The most widely used methodology is sequential single breath inhalations with a dosimeter to establish the concentration of tussive agent causing two and five coughs (C2 and C5 respectively) [32, 33]. Cough reflex challenge tests are valuable tools

Conclusion

There are numerous validated tools available to assess cough. A combination of subjective and objective measures is desirable. In a clinical setting the severity of cough can easily be assessed by asking the patient to rate it on a scale between 0 and 10. In clinical trials of antitussive medications objective measures such as cough frequency monitors are being increasingly used as primary endpoints. They should always be accompanied by secondary outcome measures assessing symptom severity and

Conflict of interest statement

Surinder S. Birring is a developer of quality of life and cough monitoring tools.

Arietta Spinou was funded by the Greek State Scholarships Foundation (IKY) for her PhD studies. IKY had no involvement in this publication.

References and recommended reading

Papers of particular interest, published within the period of review, have been highlighted as:

  • • of special interest

  • •• of outstanding interest

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