Cough measurements in idiopathic pulmonary fibrosis (IPF) patients
Cough measurement tool | Description | Validation studies and MCID | Advantages | Disadvantages |
Subjective | ||||
Visual analogue scale [56] | 100 mm scale with extremes no cough to worst possible cough severity | Not validated in IPF | Easy to use Repeatable Responsive | Not validated in IPF or chronic cough |
Cough quality-of-life questionnaire [57] | 28-item cough-specific quality-of-life questionnaire with six domains | Validated in IPF (n=23) MCID in IPF: change of five points on a 28–112 scale [57] | Comprehensive questionnaire Reliable Valid instrument for assessing impact of cough | Need more studies in IPF: MCID evaluated with a retrospective anchor scale |
Leicester cough questionnaire [15] | 19-item self-administered chronic cough quality-of-life questionnaire with three domains | Evaluated in IPF: high correlation found with cough visual analogue scale, cough symptom score and objective cough frequency in IPF [10, 22] MCID in chronic cough: 1.3 | High reliability Valid instrument for assessing impact of cough Ability to detect a response to change | Need more studies in IPF: MCID evaluated in chronic cough |
Objective | ||||
Cough challenge test [58] | Measurement of cough reflex sensitivity by inhalation of nebulised tussive agents (most common citric acid or capsaicin) | Not validated in IPF No MCID Standardised methodology published by ERS [14] | Useful for testing effect of new cough therapies on cough reflex sensitivity and for obtaining mechanistic insights | Doesn't measure efficacy of therapy or predict response in patients Limited availability |
Cough monitor [59] | Microphone and recording device measuring cough in a pre-specified time slot | Validated cough monitors for chronic cough High correlation found with subjective cough measurements [10] | Measures cough frequency accurately | Currently limited to research and trails Benefit in routine clinics is not clear |
MCID: minimal clinically important difference; ERS: European Respiratory Society.