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CHAT, a novel 18-item patient-reported questionnaire, shows promise as a clinical and research tool for evaluating cough hypersensitivity in chronic cough.

The Cough Hypersensitivity Assessment Test (CHAT), a novel 18-item patient-reported questionnaire, demonstrates strong potential as a clinical and research tool for evaluating cough hypersensitivity in patients with chronic cough.

The 18-item test of “chemical, mechanical and thermal triggers has good reliability, validity and responsiveness, and can be used to identify the individual differences in the degree of cough hypersensitivity, which might be a valuable and complementary tool for clinical trials and management of chronic cough,” Kefang Lai, MD, PhD, and colleagues, who developed the tool in China, reported in JACI: In Practice.

“More importantly, CHAT may be used as a new tool for measuring cough hypersensitivity in clinical research,” they noted.

Bridging a Diagnostic Gap in Chronic Cough Assessment

Objective cough provocation tests —such as capsaicin, citric acid, and ATP—offer insight into cough reflex sensitivity. Yet, they typically engage specific chemoreceptors and fail to capture the holistic sensitivity mediated by various pathways. Moreover, test results can overlap between patients with and without chronic cough, limiting diagnostic clarity, the researchers wrote.

Existing questionnaires also have limitations. While the HARQ (Hull Airway Reflux Questionnaire) focuses on reflux-related cough symptoms, it does not adequately quantify cough hypersensitivity. The CHQ (Cough Hypersensitivity Questionnaire) is more comprehensive, but it lacks normative validation, according to the authors. These gaps underscored the need for a more refined instrument.

To address this, Dr. Lai and colleagues designed the CHAT based on a literature review, expert opinion, and clinical experience. The tool was evaluated in 230 patients with chronic cough and 102 control participants without cough. Both groups had similar mean ages—36.9 and 36.0 years, respectively.

CHAT Questionnaire Structure

According to the researchers, all participants completed the CHAT, and chronic cough patients also completed additional assessments, including the Visual Analogue Scale (VAS), Cough Symptom Score (CSS), HARQ, CHQ, and Leicester Cough Questionnaire (LCQ). Patients with chronic cough were asked, “In the past month, have you experienced a cough or an aggravation of an existing cough owing to the following triggers/symptoms?” Control participants were asked, “In the past 4 weeks, without having conditions like upper respiratory tract infections, have you experienced a cough owing to the following triggers/symptoms?”

CHAT questions were scored using a 5-point Likert scale, ranging from 0 (low probability of cough) to 4 (high probability), for a total score of 0 to 72. Total scores of 18 or above indicated hypersensitivity. The items were classified as environmental triggers (eg, pollutants, cold air), daily life triggers (eg, talking, eating), and tussive symptoms (eg, dry throat, urge to cough).

Cough Hypersensitivity Common in Chronic Cough

Patients with chronic cough had a mean CHAT score of 28.3, compared to 6.0 among controls (P<0.001). Overall, 77.8% of chronic cough patients and 7.8% of healthy controls scored 18 or above. These results suggest that cough hypersensitivity is prevalent in individuals with chronic cough but may also exist in a small percentage of healthy individuals, the researchers wrote.

Patients were much more susceptible to cough triggers and sensory dysfunction, including irritating smells and foods, allergens, air pollutants, cold air, talking, eating, physical exercise, and abnormal sensations.

The internal consistency was strong (Cronbach’s alpha, 0.832), and test-retest reliability supported stability over time (intraclass correlation coefficient, 0.884).

CHAT scores correlated more strongly with the HARQ and CHQ than with the LCQ or visual analogue scale (VAS) of cough severity.

Of the 40 patients who underwent capsaicin challenge, 55% met criteria for hypersensitivity. Patients with capsaicin cough sensitivity exhibited higher tussive symptoms (P=0.007) and total CHAT scores (P=0.029).

Future Implications & Research Directions

Despite promising findings, the authors acknowledged notable limitations of the study; It was conducted at a single center, relied exclusively on capsaicin for objective comparison, and did not stratify results by cough etiology. “Further validation of the CHAT, its cut-off point, and the MCID in diverse clinical settings is needed before broader application,” the authors advised.

Nonetheless, the authors concluded, “The CHAT comprehensively covers a range of cough triggers and shows robust internal reliability, test-retest reliability, construct validity, and responsiveness. This may be useful for measuring cough hypersensitivity.”