Researchers Develop 51-Item Framework for Cough Severity Measurement

Using information collected from patient focus groups and expert panel members, researchers have developed a 51-item framework to measure cough severity, including the domains of urge-to-cough sensations and cough symptoms.

Existing instruments to measure cough severity include the visual analogue scale and Cough Severity Diary (CSD), however, both have their limitations.

This new framework was published in ERJ Open Research and created using input from 16 adult patients with refractory or unexplained chronic cough from Canada, and an international panel of 15 experts.

The 16-person focus group had a median age of 61 years, with most (68.8%) identifying as female and reporting no history of smoking (81.3%). The median cough duration of the group was 13.5 years.

Consensus of the items and domains of the framework were reached following a systematic survey and a series of virtual meetings.

An initial list of 48 items under 2 domains was formed based on the focus group’s feedback, followed by an open-ended survey where the expert panel identified 32 potential items they considered relevant to cough symptom severity.

In the finalized framework, 51 items were categorized under 2 broader domains: urger-to-cough and cough symptoms.

The urge-to-cough sensation domain included the subdomains of frequency and intensity. The cough symptom domain included subdomains of triggers, control, frequency, fit/bout duration, intensity, quality, and associated features/sequelae. Additional factors were listed within those subdomains.

“The results support item generation and content validity for a novel patient-reported outcome measure for use in health research and clinical practice,” the authors said.

The authors cited multiple reasons why a cough severity measurement instrument is important:

• Patients can find the same symptom to vary in how much it impacts their quality of life (QoL), regardless of severity.
• Duration of chronic cough can have a cumulative impact of QoL even if symptom severity doesn’t change.
• Neuromodulatory agents can improve cough QoL, but may not necessarily affect cough frequency.
• Single-item cough frequency monitors can objectively measure cough, but are limited in their clinical use.
• A cough severity instrument that also factors in cough symptoms and urge-to-cough sensations may help to identify subgroups of patients who share cough pathophysiology.

A qualitative study used to develop the CSD also identified intensity, frequency, and disruption as factors under cough severity.

“Although our results are consistent with themes identified in their study, our work differs in that we involved patient partners and experts to optimally define the measurement construct of a cough symptom severity instrument and strove for conceptual clarity by excluding items/domains related to cough impact on QoL,” the authors said.

However, limitations of this framework include a small, single-center sample of only English-speaking individuals. Potential selection bias of experts, potential response bias among focus group participants, and subjectivity of the interpretation of themes leading to consensus were also noted.

“Future studies should address items and domains that are most important to patients for item reduction of a cough symptom severity questionnaire,” the authors said.

Reference

Kum E, Guyatt GH, Munoz C, et al. Assessing cough symptom severity in refractory or unexplained chronic cough: findings from patient focus groups and an international expert panel. ERJ Open Res. 2022;8(1):00667-2021. doi:10.1183/23120541.00667-2021