Affecting nearly 339 million people worldwide, asthma is the most common chronic condition in childhood and is responsible for over 1000 deaths a day, of which the majority are preventable.¹ It poses a substantial burden on society and healthcare systems with prevalence and disease burden continuing to rise.² In the US alone, medical costs for people with asthma are estimated to be $3,266 higher per year compared to medical costs for people without asthma.³

At the most basic level, asthma is a chronic inflammatory airway disease characterised by variable airflow limitation. This leads to the hallmark symptoms of asthma, including cough, wheeze, chest tightness, and shortness of breath. Beyond this simplified description, asthma is a highly heterogeneous condition, with substantial symptomatic overlap with other chronic respiratory diseases and a wide range of recognised phenotypes. Asthma symptoms fluctuate markedly over time, often varying day to day and occurring episodically in response to specific triggers. This variability makes accurate diagnosis and assessment challenging, particularly when clinical decisions are based on brief consultations and subjective patient recall.

Cough and Wheeze in Asthma

Cough and wheeze are the characteristic and most prevalent symptoms of asthma, alongside shortness of breath and chest tightness. However, they appear to represent distinct dimensions of disease rather than interchangeable markers of asthma activity. This highlights the importance of measuring both symptoms alongside pulmonary function tests.

Cough: Inflammation and Airway Sensitivity

Cough in asthma is primarily driven by airway inflammation and heightened cough reflex sensitivity. Inflammatory mediators irritate airway sensory nerves, lowering the threshold at which a patient coughs. As a result, relatively minor triggers – cold air, allergens, viral infections, exercise – can provoke persistent coughing. In some individuals, cough is the dominant manifestation of asthma (“cough-variant asthma”), often in the absence of obvious wheeze.

Notably, cough burden does not always correlate with lung function tests – patients may feel significant disease burden even when lung function appears relatively preserved.⁴

Clinical relevance

• Quality of life: Chronic or frequent cough is disruptive and has a greater negative impact on QoL than any other asthma symptom.⁵ It interferes with sleep, concentration, work productivity, and social interactions. Patients often describe embarrassment, fatigue, and anxiety related to unpredictable coughing episodes.
• Exacerbations and disease progression: Presence of cough significantly correlates with poor asthma control and future risk of asthma exacerbations.⁵ In fact, worsening of cough is reported to have the highest predictive weight for predicting progression to severe asthma.⁶

In short, cough may serve as an early indicator of clinical instability, even when traditional pulmonary function measures such as FEV₁ and FVC remain unchanged.

Wheeze: Airflow Narrowing and Bronchoconstriction

Wheeze is a high-pitched sound produced when air flows through narrowed airways during expiration. It reflects mechanical airflow obstruction, typically due to bronchoconstriction, mucosal edema, or mucus accumulation.

Unlike cough – which may be driven by neural hypersensitivity and reflect symptom burden – wheeze generally implies reversible structural airway narrowing and impaired lung function.^5,7

Clinical relevance

• Quality of life: Wheeze is commonly associated with dyspnea and chest tightness. Patients may limit exertion to avoid symptoms, leading to reduced physical activity and overall health. Nocturnal wheezing, in particular, is strongly associated with impaired sleep.⁸
• Exacerbation and disease progression: Increasing wheeze intensity, duration, or frequency often indicates declining lung function. Evidence suggests that wheeze is a significant risk factor for exacerbations, independently from cough.⁹

Despite their clinical significance and importance to patients, cough and wheeze are typically not assessed in clinical trials with the same granularity or objectivity as airway obstruction or inflammation.⁶

Measuring Cough and Wheeze in Asthma

Traditionally, asthma symptoms have largely been assessed using patient-reported outcomes (PROs). In clinical practice, the Asthma Control Test (ACT) and Asthma Control Questionnaire (ACQ) are most commonly used. However, neither includes items specific to cough and only the ACQ addresses wheeze. In clinical trials, more in-depth instruments like the Asthma Quality of Life Questionnaire (AQLQ), Severe Asthma Questionnaire (SAQ), and St George’s Respiratory Questionnaire (SGRQ) are frequently employed. They acknowledge cough and wheeze in relation to quality of life, but don’t provide an objective measure of symptom frequency or severity.^10,11 

Objective symptom monitoring adds a layer of disease insight not visible through spirometry or PROs.¹² Earlier technologies were limited by factors such as battery life and portability, constraining their use in real-world settings.¹⁰ However, recent advances have addressed many of these limitations. Newer devices, such as the RESP® Biosensor, enable convenient objective measurement of both cough and wheeze over a period of hours or days, rather than minutes. They also provide the ability to analyze captured data in novel ways, such as diurnal variations or the relationship between dosing and time to findings.

What Does it Mean Moving Forward?

Including objective wheeze and cough measures into a clinician’s toolbox enables more accurate phenotyping, a clearer understanding of disease burden and earlier detection of exacerbations. For sponsors and investigators, it provides the opportunity for more meaningful endpoints and analysis, to track treatment response beyond FEV₁ and exacerbations.

Ultimately, as asthma management continues to move toward personalized, treatable trait–based care, including objective measures of cough and wheeze can help ensure that the aspects of disease that matter most to patients are more accurately understood, monitored, and addressed.

References

1. Global Asthma Network. The Global Asthma Report 2018. Global Asthma Network; 2018. Accessed February 2026. https://globalasthmareport.org/2018/resources/Global_Asthma_Report_2018.pdf
2. Wang Z, Li Y, Gao Y, et al. Global, regional, and national burden of asthma and its attributable risk factors from 1990 to 2019: a systematic analysis for the Global Burden of Disease Study 2019. Respir Res. 2023;24(1):169. Published 2023 Jun 23. doi:10.1186/s12931-023-02475-6
3. Nurmagambetov T, Kuwahara R, Garbe P. The Economic Burden of Asthma in the United States, 2008-2013. Ann Am Thorac Soc. 2018;15(3):348-356. doi:10.1513/AnnalsATS.201703-259OC
4. Aburuz S, McElnay J, Gamble J, Millership J, Heaney L. Relationship between lung function and asthma symptoms in patients with difficult to control asthma. J Asthma. 2005;42(10):859-864. doi:10.1080/02770900500371187
5. Lee HY, Lee Y, Lee JH, et al. Association of Cough Severity with Asthma Control and Quality of Life in Patients with Severe Asthma. Lung. 2024;202(4):405-414. doi:10.1007/s00408-024-00710-5
6. Lai K, Satia I, Song WJ, et al. Cough and cough hypersensitivity as treatable traits of asthma. Lancet Respir Med. 2023;11(7):650-662. doi:10.1016/S2213-2600(23)00187-X
7. Bermúdez Barón N, Lindberg A, Stridsman C, et al. Among respiratory symptoms, wheeze associates most strongly with impaired lung function in adults with asthma: a long-term prospective cohort study. BMJ Open Respir Res. 2021;8(1):e000981. doi:10.1136/bmjresp-2021-000981
8. Sutherland ER. Nocturnal asthma. J Allergy Clin Immunol. 2005;116(6):1179-1187. doi:10.1016/j.jaci.2005.09.028
9. Chen W, Puttock EJ, Xie F, et al. Symptoms of Asthma Extracted Through Natural Language Processing and Their Associations With Acute Asthma Exacerbation in Adults With Mild Asthma. J Allergy Clin Immunol Pract. 2025;13(7):1719-1729.e7. doi:10.1016/j.jaip.2025.04.031
10. Holmes J, Heaney LG, McGarvey LPA. Objective and Subjective Measurement of Cough in Asthma: A Systematic Review of the Literature. Lung. 2022;200(2):169-178. doi:10.1007/s00408-022-00527-0
11. Worth A, Hammersley V, Knibb R, et al. Patient-reported outcome measures for asthma: a systematic review. NPJ Prim Care Respir Med. 2014;24:14020. Published 2014 Jun 26. doi:10.1038/npjpcrm.2014.20
12. Marsden PA, Satia I, Ibrahim B, et al. Objective Cough Frequency, Airway Inflammation, and Disease Control in Asthma. Chest. 2016;149(6):1460-1466. doi:10.1016/j.chest.2016.02.676