Objective cough frequency in Idiopathic Pulmonary Fibrosis

TLDR

Cough is a common presenting symptom in patients with Idiopathic Pulmonary Fibrosis (IPF). The study measured cough rates in IPF patients and examined their association with health‑related quality of life, subjective cough severity, physiological disease severity, and cough rates in other respiratory conditions. The study recruited 19 IPF patients (mean age 70.8 yr) who underwent pulmonary function testing, 24‑hour ambulatory cough recordings, Leicester Cough Questionnaire, and visual analogue scale assessments. Objective cough rates were high (median 9.4 coughs/h, day 14.6 vs night 1.9) and strongly correlated with VAS (day r = 0.80, night r = 0.71) and LCQ (r = –0.80), but not with pulmonary function; IPF cough rates exceeded those of healthy controls and asthma patients but matched chronic cough patients, confirming cough as a major, distressing symptom in IPF.

Abstract

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.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.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).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.