Comparisons of cough reflex sensitivity and urge-to-cough between control subjects (Control) and patients with aspiration pneumonia (Patient). (A) Cough reflex sensitivities expressed as the log transformation of the lowest concentration of citric acid that elicited five or more coughs (C2). (B) The urge-to-cough estimated by the Borg scores at C2 of each subject. (C) The urge-to-cough estimated by the Borg scores at the concentration of two times dilution of C2 (C2/2) of each subject. Closed circles indicate the value of each subject. Open circles and error bars indicate the mean value and the standard deviation in each group, respectively. n.s. denotes not significant.