A Systematic Review of Methods of Citric Acid Cough Reflex Testing

A Systematic Review of Methods of Citric Acid Cough Reflex Testing. Citric acid cough reflex testing (CRT) is used across disciplines to evaluate the sensory integrity of the cough reflex and to evaluate the efficacy of anti-tussive medications. 

According to the European Respiratory Society (ERS), one of the primary challenges with citric acid CRT is the lack of standardized procedures within and across disciplines (Morice et al., 2007). This makes it difficult to compare results across studies and to choose optimal methods of citric acid CRT in terms of validity and reproducibility. 

In 2007, the ERS produced guidelines on the assessment of cough and described a standardized method of citric acid CRT (Morice et al., 2007). Despite these guidelines, many methods of citric acid CRT continue to be published. 

The aim of this cross-discipline, systematic review was to evaluate all available primary research on citric acid CRT in order to (1) highlight the disparity of citric acid CRT methods and (2) to inform the methodological design of citric acid CRT to optimize validity and reproducibility for future research studies.