Cough and gastroesophageal reflux: identifying cough and assessing the efficacy of cough-modifying agents

From a symptom research standpoint, much has been learned about the management of cough in general and cough caused by gastroesophageal reflux disease in particular. Yet, before further advances can be made in our understanding of how to best manage patients with this common symptom, methodologic challenges remain to be solved. One of the most basic is the development of valid and reliable methods by which to identify cough, assess its impact on patients, and assess the efficacy of cough therapies. Herein, we review the characteristics of cough that relate to its assessment and how the effect of drug treatment on cough has been assessed. Perspective is provided on evaluating the efficacy of cough-modifying agents and the optimal method for identifying a cough and linking it with a reflux event. Investigators should use both subjective and objective methods, because they have the potential to measure different aspects of cough. Subjective measures, such as a cough-specific quality-of-life instruments, are likely to best reflect the severity of cough from the patient’s standpoint, because a subjective response most likely integrates both cough frequency and intensity. The ideal objective method should allow cough to be automatically counted over 24 hours in an ambulatory setting. Although it is theoretically possible to design and construct such a device that is also relatively unobtrusive, reliable, and accurate, one is not yet available.