The objective assessment of cough frequency: accuracy of the LR102 device

Ten adult patients complaining of cough were recruited in primary care and hospital settings. Participants were asked to wear LR102 for 4 consecutive hours during which they were also filmed.Measures of cough frequency by LR102 and manual counting were closely correlated (r = 0.87 for number of cough episodes per hour; r = 0.89 for number of single coughs per hour) but LR102 overestimated cough frequency. Bland-Altman plots indicate that differences between the two measurements were not influenced by cough frequency.LR102 offers a useful estimate of cough frequency in adults in their own environment, while significantly reducing the time required for analysis.Cough is a common reason for seeking medical care [1,2]. Not only is it a prevalent problem, it also has a significant impact on quality of life [3-6]. Yet it has not been extensively studied using objective measures. The evaluation of a cough, in clinical practice but also in most clinical trials, is usually based on patients' subjective assessment.The studies that have used objective measurements have reported inconsistent correlations between objective and subjective measurements [7-19]. The following assessment tools are currently available: cough monitors used to objectively measure cough frequency, and quality-of-life questionnaires, verbal descriptive scores (VDS), and visual analogue scales (VAS) used to subjectively measure cough severity. The assessment of cough severity can involve several different aspects: (1) the importance of the cough, objectively measured in terms of the frequency or intensity of the expulsive effort (2) the impact of the cough on the patient's quality of life and (3) the importance of the cough as perceived by the patients [20]. In a recent systematic literature we reported the psychometric characteristics of three validated cough-specific quality-of-life scales (Leicester Cough Questionnaire, Cough Quality of Life Questionnaire, and Burden of Cough Questionnaire). However we