Research
Objective cough frequency in Idiopathic Pulmonary Fibrosis
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* Corresponding author: John E Earis J.E.Earis@liverpool.ac.uk
- † Equal contributors
1 Respiratory Department, Aintree University Hospitals NHS Foundation Trust, University Hospital Aintree, Longmoor Lane Liverpool, L9 7AL, UK
2 Respiratory Research Group, School of Translational Medicine, University of Manchester, 2nd Floor, Education and Research Centre, Wythenshawe Hospital, Southmoor Road, Manchester M23 9LT, UK
3 School of Environment and Life sciences, University of Salford, Salford, Greater Manchester, M5 4WT UK
Cough 2010, 6:4 doi:10.1186/1745-9974-6-4
Published: 21 June 2010Abstract
Background
Cough is a common presenting symptom in patients with Idiopathic Pulmonary Fibrosis (IPF). This study measured cough rates in IPF patients and investigated the association between cough and measures of health related quality of life and subjective cough assessments. In addition, IPF cough rates were related to measures of physiological disease severity and compared to cough rates in health and other respiratory conditions.
Methods
Nineteen IPF patients, mean age 70.8 years ± 8.6, five female (26.3%) were studied. Subjects performed full pulmonary function testing, 24 hour ambulatory cough recordings, completed a cough related quality of life questionnaire (Leicester Cough Questionnaire) and subjectively scored cough severity with a visual analogue scale. Ambulatory cough recordings were manually counted and reported as number of coughs per hour.
Results
The 24hr cough rates were high (median 9.4, range 1.5-39.4), with day time rates much higher than night time (median 14.6, range 1.9-56.6 compared to 1.9, range 0-19.2, p = 0.003). Strong correlations were found between objective cough frequency and both the VAS (day r = 0.80, p < 0.001, night r = 0.71, p = 0.001) and LCQ (r = -0.80, p < 0.001), but not with measures of pulmonary function. Cough rates in IPF were higher than healthy subjects (p < 0.001) and asthma patients (p < 0.001) but similar to patients with chronic cough (p = 0.33).
Conclusions
This study confirms objectively that cough is a major, very distressing and disabling symptom in IPF patients. The strong correlations between objective cough counts and cough related quality of life measures suggest that in IPF patient's, perception of cough frequency is very accurate.