What are cough bouts all about?

Why measuring cough patterns matters

What is a cough bout?

Research indicates that chronic cough patients often describe coughing in bouts, spells, fits or using other similar terms to describe coughing a lot in a short space of time⁵. There is no agreed scientific or clinical definition of such events, however, researchers have been using an operational definition of cough bouts where single coughs are separated from coughs that occur within a short period of time from each other (inter-cough interval). The most commonly used inter-cough interval threshold to define bouts to-date has been 2 seconds. A recent publication demonstrates that the effect of clustering coughs into bouts using an inter-cough interval threshold larger than 3 seconds does not seem to provide a meaningful analytical benefit when bout parameters, such as number of bouts or time spent coughing in bouts are considered^4,6.

_{Figure 1. Illustration of grouping coughs into bouts – coughs that are within 2 seconds of each other are grouped into bouts. One individual cough is present > 2 seconds away from any cough on either side of it, deeming it to be a single cough not within a bout.}

How cough bouts are measured

Modern cough monitoring systems detect and time-stamp individual cough events. This makes it possible to explore cough event clustering using different approaches. Most commonly, these events are grouped into bouts using a defined inter-cough interval threshold e.g. 2 seconds, enabling analysis of metrics such as bout frequency, bout duration, total time spent coughing (in bouts) and inverse metrics such as cough-free time^4,7,8.

Cough frequency vs cough bouts

Cough frequency measures how many coughs occur over time, whereas cough bouts account for how closely together those coughs group. Two patients may have the same cough count, but very different coughing patterns if one has isolated coughs and the other experiences prolonged coughing fits⁴. This difference seems likely to affect the patient experience of cough.

Why cough bouts matter clinically

Cough bout measures may better reflect patient experience because people most often describe the symptoms that affect their quality of life in terms of coughing fits or loss of control rather than isolated cough events^4,7,9,10. It could also facilitate a better understanding of the underlying mechanisms of coughing, for example, the central and peripheral pathways involved in the ability to control cough and how cough events trigger further coughing leading to bouts¹¹. As a simple objective measure, bouts may capture severity beyond cough frequency by revealing temporal patterns.

Challenges

A key challenge is the lack of clinical consensus on how cough bouts should be defined, as different definitions can produce different interpretations. Correlations with patient-reported outcomes also remain insufficiently established, underlining the need for further research.

Future Development

In order to support more consistent interpretation of cough patterns and strengthen the value of objective cough bout analysis as a clinical and research endpoint, future areas for development should focus on better defining patterns of cough, developing measures that reflect cough control and the episodic nature of cough, and establishing their relationship to patient-reported severity and quality of life. Further research is needed to identify which metrics, including bout frequency, bout duration, total time spent coughing and cough-free time, are most informative in clinical trials and routine care.

Conclusion

Cough frequency remains an important metric for assessing severity and treatment effect, but it does not fully reflect how patients experience cough. Cough bouts offer a complementary and potentially more clinically meaningful view of cough pattern, but their wider value will depend on a standardised definition, validation against patient-reported burden and identification of the most useful bout-based metrics. Progress in these areas will support more relevant endpoints for both clinical research and routine care.

References

1. Jiménez-Gómez M. Chronic cough as a disease: a mechanism-based framework for diagnosis and management. Medicina Clínica. 2026;166:107289. doi:10.1016/j.medcli.2025.107289.

2. Fontana GA, Widdicombe J. What is cough and what should be measured? Pulmonary Pharmacology & Therapeutics. 2007;20(4):307–312. doi:10.1016/j.pupt.2006.11.009.

3. Zimmer A, Das R, Lopez P, et al. Objective cough counting in clinical practice and public health: a scoping review. The Lancet Digital Health. 2025;7. doi:10.1016/j.landig.2025.100908.

4. Holt KJ, et al. An exploration of clinically meaningful definitions of cough bouts. ERJ Open Research. 2024;10(6):00316-2024. doi:10.1183/23120541.00316-2024.

5. Bali V, et al. Patient-reported experiences with refractory or unexplained chronic cough: a qualitative analysis. Therapeutic Advances in Respiratory Disease. 2024;18. doi:10.1177/17534666241236025.

6. Dockry RJ, Holt KJ, Smith JA, McGuinness K. S17 A relevant definition of cough bouts. Thorax. 2022;77(Suppl 1):A14–A15. doi:10.1136/thorax-2022-BTSabstracts.23.

7. Holt KJ, et al. Investigating cough bouts in idiopathic pulmonary fibrosis (IPF). American Journal of Respiratory and Critical Care Medicine. 2025;211:A3232. doi:10.1164/ajrccm.2025.211.Abstracts.A3232.

8. Decalmer S, et al. Temporal relationships between reflux and cough. American Journal of Respiratory and Critical Care Medicine. 2009;179:A5765.

9. Smith J, et al. Clinical trial outcome measures in cough. In: Song W-J, McGarvey L, Cho PSP, et al., editors. Chronic Cough. ERS Monograph. Sheffield: European Respiratory Society; 2025. p. 94–106. doi:10.1183/2312508X.10027024.

10. Kum E, Guyatt GH, Abdulqawi R, et al. The McMaster Cough Severity Questionnaire (MCSQ): a cough severity instrument for patients with refractory chronic cough. European Respiratory Journal. 2025;65:2401565. doi:10.1183/13993003.01565-2024.

11. Smith J. The significance and psychosocial burden of refractory chronic cough. EMJ Respiratory. 2025. Accessed 11 June 2026. https://www.emjreviews.com/respiratory/article/the-significance-and-psychosocial-burden-of-refractory-chronic-cough-interview-with-two-key-opinion-leaders-and-a-patient-s160225/