Measuring cough: what really matters?

Abstract

The clinical and research discipline of cough has grown substantially over the last two decades as methods to measure cough have developed and evolved. Cough can be thought of both as a symptom and an objectively observable pathophysiological phenomenon, two aspects whose interrelationship is complicated. The following review explores the varied methods to measuring cough, both subjective, patient-reported measures and objective approaches. Specifically, symptom scores, questionnaires of cough-related quality of life, and associated mental health impacts of chronic cough are addressed, as are developments in measuring cough frequency, cough intensity, cough reflex sensitivity, and cough suppressibility. Measuring patient reported cough-severity with a simple visual analogue scale increasingly appears to be justified, but has limitations. The Leicester Cough Questionnaire has been widely used for twenty years, within varied settings and diseases, in research and routine clinical practice, and captures cough-related quality of life. Objective cough frequency has become the primary outcome measure for clinical trials of antitussives, and technology is now enabling the wider application of cough counting. Inhaled tussive challenge testing still has a role, including in the assessment of cough hypersensitivity, and in the identification of failure to supress cough. Ultimately, many measures have a contributory and complementary role, with differing merits in quantifying the multiple facets of cough, the complexity of which is being increasingly recognised.

Potassium-Competitive Acid Blocker Versus Proton Pump Inhibitor: A Pilot Study on Comparable Efficacy in the Treatment of Gastroesophageal Reflux-Related Cough

“… 36 There was only moderate correlation between cough severity VAS score and LCQ score. 37 What is more, the perception of the impact on quality-of-life has individual variances due to age, education, social background, and so on.…”

Antitussive Use in Patients with Inadequately Controlled Moderate-to-Severe Asthma: A Post Hoc Analysis of the Omalizumab EXTRA Trial

“…12 There are several limitations of this analysis. The exploratory post hoc nature limits interpretation; the assessment of antitussive use was limited to reports of concomitant medication (because it was not a prespecified outcome of EXTRA); and an objective, subjective, or patient-reported measure of cough (such as those considered by Turner et al 13 ) was not assessed. In addition, though expected to be uncommon in a clinical trial, there is a possibility of non-reported selfmedication of antitussives.…”

Chronic cough: is the end nigh?

“…One problem for studies in this area was poor recording and classification in healthcare databases due to a lack of specific coding for chronic cough. This changed in 2022, as the World Health Organization International Classification of Diseases (10 th revision) introduced a code for chronic cough (R05.3), hopefully enabling chronic cough to be increasingly recognised and recorded as a discrete disease in its own right, rather than a symptom of another disorder [ 29 ].…”

“…Despite multiple objective and subjective options for measuring cough, diagnoses of chronic cough can be difficult. Tools to measure objective cough frequency, cough severity and cough-specific quality of life are used in clinical and research settings, and have been essential for progress [ 2 , 22 , 29 ]. However, there is currently no gold standard investigation for a diagnosis of (refractory or unexplained) chronic cough, and a limited availability of cough frequency monitoring or tussive challenge testing for general use.…”

“…However, there is currently no gold standard investigation for a diagnosis of (refractory or unexplained) chronic cough, and a limited availability of cough frequency monitoring or tussive challenge testing for general use. Moreover, these tests have uncertain utility in clinical practice with limited associations demonstrated between cough frequency and important patient-reported outcomes [ 29 ], and significant overlap between objective CRS in chronic cough and health [ 11 ]. Diagnosis of underlying causes of chronic cough, such as cough variant asthma or eosinophilic bronchitis, is often retrospective from response to treatment, rather than on objective testing.…”