24-hour cough frequency has traditionally been recognized as the ‘gold standard’ primary endpoint for indications such as refractory chronic cough, chronic bronchitis, and IPF-related cough. While frequency is undoubtedly a valuable metric to measure for cough, there are other measurements often overlooked that can provide much greater insight into the true burden of the patient’s cough. In this blog post, we will explore the benefits of going deeper by measuring cough intensity, cough bouts, respiratory rate, and activity level to gain more clinical context and strengthen evidence for treatment response.
Limitations of Cough Count
Cough count, or frequency, is valuable in offering an objective metric of cough to complement patient reporting of symptoms, data that is subject to incompleteness, bias, and variability. The main drawback with cough count as a single measure is that it doesn’t shed light on other elements that we consider to be important.
- Cough count doesn’t differentiate between dry or productive cough, coughs triggered by specific factors, or cough intensity.
- Counting the number of coughs in a period doesn’t tell you when in the period they occurred. This makes it impossible to identify coughing bouts and spasms that have a much greater burden on patients.
- Cough can interact with or have an impact on other respiratory functions such as breathing patterns and shortness of breath. Coughing can also impact a patient’s quality of life by limiting their physical activity, social interactions, sleep, and even work performance.
Limiting measurement to frequency without the addition of other measures limits insights and breakthroughs in our understanding and treatment of cough.
Expanding the Endpoint Toolkit for Cough
While questionnaires such as the Leicester Cough Questionnaire and VAS help to uncover some of the elements discussed above, clinical trialists can also capture them objectively with wearable technologies such as the RESP® Biosensor, which captures lung sounds. Below are additional parameters our partners have been able to collect to gain a more complete picture of patient well-being related to cough:
- Cough Intensity: By capturing the sound levels of cough in decibels, clinical trialists can add another valuable, quantifiable metric beyond count.
- Cough Bouts or Spasms: Identifying coughing events as single coughs or cough bouts.
- Respiratory Rate* and Wheeze: Measuring respiratory rate and wheeze can offer objective measures of breathing patterns and airway obstruction to gain insight into the respiratory distress experienced by patients when they cough.
- Activity Level*: Capturing subjects’ steps, sleep/wake, and body positioning can help tell the story around a patient’s ability to engage in daily activities, their sleep quality, and overall well-being relating to their cough.
As drug developers seek to demonstrate the effectiveness of their cough treatments, it is time to go beyond cough count. By adding measurements such as cough intensity, bouts, respiratory rate, and activity level, clinical trialists can gain a more comprehensive understanding of their subjects’ cough and build a stronger case for their treatment.
*Measurement not FDA-cleared and for investigational use only.