Development of the Rapid Cough Questionnaire: Key item identification

Abstract

Background: The Leicester Cough Questionnaire (LCQ) is a reliable tool for measuring the multidimensional impact of cough on patients’ quality of life; however, its scoring algorithm is lengthy and complex for routine clinical use. Objective: The study aimed to develop a simplified version of the LCQ, the Rapid Cough Questionnaire (RCQ), as a substitue in clinical practice and validate the RCQ using an independent cohort. Methods: To select items for the RCQ score, a correlation network was used to determine the items from each domain that were strongly correlated with the total LCQ score. The final items for the RCQ were selected on the basis of the centrality of the node degree, betweenness, and closeness in the correlation network. Results: The RCQ score was derived from 3 items: tiredness (LCQ3) in the physical domain, the feeling of being fed up (LCQ13) in the psychological domain, and annoyance with partner/family/friends (LCQ19) in the social domain. The correlation between the LCQ and RCQ was high, with a coefficient of 0.93 (P < .001). The mean score of the RCQ was 11.2 ± 3.2, with scores ranging from 5.15 to 19.55. The minimal clinically important difference in the RCQ score was calculated to be 1.6 using a distribution-based method. The concurrent validity of the LCQ and the RCQ with cough numeric rating scale was similar. In the validation cohort, the correlation between the LCQ and RCQ scores was consistent regardless of sex and etiology. Conclusion: The RCQ score, which is concise, reliable, and valid, can be a valuable tool for patient assessment, particularly in clinical practice.