Cough frequency, cough sensitivity and health status in patients with chronic cough.
BACKGROUND
Little is known about the frequency of cough in health and in patients with chronic cough.


METHODS
We measured cough frequency and its relationship with other markers of cough severity in 20 patients with chronic cough and 9 healthy subjects using the Leicester Cough Monitor (LCM), which is an automated ambulatory digital cough monitor that records sound only. All subjects had a 6-h recording and recordings were manually counted. A subgroup of 6 normals and 6 patients with a stable chronic cough had repeat measurements up to 6 months apart.


RESULTS
Mean (sem) cough counts/hour were 43(8) in patients with chronic cough and 2(1) in normals (mean difference 41; 95% confidence interval 24-59; P<0.001). The cough counts were repeatable (within subject standard deviation: 23 coughs/hour; intraclass correlation coefficient 0.8). Cough counts correlated significantly with physical (r=-0.6, P=0.03), social (r=-0.7, P=0.01) and total Leicester Cough Questionnaire (LCQ) health status scores (r=-0.6, P=0.03) and cough sensitivity (concentration of capsaicin causing 5 coughs: r=0.9, P=0.008).


CONCLUSIONS
We have shown that there are marked differences in cough frequency between patients with chronic cough and healthy subjects, that these measurements are repeatable, and that they correlate with cough-specific health status.
Birring
Surinder S
SS
Department of Respiratory Medicine, Institute for Lung Health, Glenfield Hospital, Leicester, LE3 9QP, UK. sb134@le.ac.uk
Matos
Sergio
S
Patel
Ronnak B
RB
Prudon
Benjamin
B
Evans
David H
DH
Pavord
Ian D
ID
D000328:Adult; D002211:Capsaicin; D016022:Case-Control Studies; D002908:Chronic Disease; D003371:Cough / Q000503:physiopathology*; D005260:Female; D006304:Health Status; D006801:Humans; D007509:Irritants; D016014:Linear Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged
D007509:Irritants; D002211:Capsaicin