The main objective of this study to review the literature on detecting cough and to make evidence-based recommendations for evaluating the efficacy of cough-modifying agents in clinical research.

MEDLINE literature review for all studies using the medical terms "assessing the impact of cough," "assessing the efficacy of cough treatments," "cough counting," "character and timing of cough," "visual analog scales," "cough scoring systems," etc. were used.

A patients subjective response is the one that measures the impact of the intensity of cough. It is recommended that a cough-specific health-related quality-of-life instrument should be utilized as valid and reliable instruments do exist. Visual analog scales are not psychometrically tested but are recommended as they are commonly used and valid. They yield different but complementary results. Cough-specific health-related quality-of-life instruments are fully psychometrically tested and should be the primary and subjective outcome measure of choice.

Regarding objective methods, tussigenic challenges can be used before and after the intervention to determine the effect of treatment on the sensitivity of cough. They are helpful in disease states in which cough reflex sensitivity is heightened. The act of coughing has the potential to traumatize the upper airway, i.e., vocal cords, which assessed the presence of upper airway edema before and after treatment with flow-volume loops. Investigators should be careful and not assume that observing changes are suggestive of inflammation and edema of upper airway structures or specific for any disease.

With a computerized methodology, cough counting is recommended as it is reliable, accurate, non-invasive, portable, and easy to use in ambulatory real-life settings in a patient’s home environment. It can also be done over a 24-h period.

Source: Irwin RS. Assessing cough severity and efficacy of therapy in clinical research: ACCP evidence-based clinical practice guidelines. Chest. 2006 Jan;129(1 Suppl):232S-237S. doi: 10.1378/chest.129.1_suppl.232S. PMID: 16428716.