Cough Hypersensitivity Syndrome: A Distinct Clinical Entity

Abstract

We postulate that most patients with chronic cough have a single discrete clinical entity: cough hypersensitivity syndrome. We constructed a questionnaire that elicits the major components of the syndrome. Here we describe the validation of this questionnaire. Following iterative development, the Hull Airway Reflux Questionnaire (HARQ) was administered to patients and normal volunteers. It is self-administered and comprises 14 items with a maximum score of 70. Unselected patients were recruited sequentially from the Hull Cough Clinic. Preclinic questionnaires were compared with those obtained at the clinic. Responsiveness was assessed 2 months after the clinic visit. One hundred eighty-five patients and 70 normal volunteers were included in this study. There was a marked difference in HARQ scores between patients with chronic cough and normal volunteers. The sensitivity (94%) and specificity (95%) of the HARQ was high, with an area under the ROC curve of 0.99. All items of the scale significantly correlated positively with others in the scale and with the total score. On repeatability testing using Cohen's kappa with quadratic weights, significant agreement was noted for all items. Good correlation was observed between the total scores (r = 0.78). The questionnaire was also responsive to treatment; the minimum clinically significant change was estimated to be 16 points. We have demonstrated the HARQ to have good construct and criterion validity. It is both reproducible and responsive to change. It can be used as a diagnostic instrument and demonstrates that chronic cough represents a single coherent entity: cough hypersensitivity syndrome.

Expert opinion on the cough hypersensitivity syndrome in respiratory medicine

“…The diagnosis of CHS comprises not only patients suffering from chronic idiopathic cough, but also encompasses patients with other conditions who demonstrate a heightened response to inhaled coughprovoking stimuli such as citric acid or capsaicin [1,2,5]. The syndrome focuses on the chronic cough patient and provides an ''umbrella'' for different conditions where cough is a major component.…”

“…Prandial, post-prandial and positional precipitation of cough, along with extra-oesophageal features such as hoarseness, throat clearing and unusual taste, can be considered as pointers [5]. The lack of confirmatory objective diagnostics is a problem.…”

Thoughts on One Thousand Chronic Cough Patients

“…However, only a very small percentage of individuals with these very common conditions develops chronic cough. Recently, the cough hypersensitivity syndrome [28][29][30] has been proposed as an explanation for the occurrence of chronic cough in a small subgroup of persons with the same common conditions that do not induce cough in the vast majority of individuals. Further work will be necessary to advance this concept in terms of insight into mechanisms of cough and potential therapeutic strategies.…”

An update and systematic review on drug therapies for the treatment of refractory chronic cough

“…CC has been labeled as a cough hypersensitivity syndrome (CHS) [18,19] with neuroinflammatory mechanisms likely to be the underlying mechanisms. The concept evolved from clinical observations of patients who had no apparent clinical cause for their cough (unexplained/idiopathic cough) or remained refractory to usual cough treatments (refractory CC) and from analogies with chronic neuropathic pain [20].…”