Validated Methods of Cough Assessment: A Systematic Review of the Literature

Background: Cough is a common symptom for which patients often seek medical advice and consume vast amounts of drugs. It is a real challenge for both the physician and the clinical researcher to evaluate a cough’s clinical importance and its precise response to treatment. Objectives: This systematic literature review has the following objectives: first, to make an inventory of the validated tools for assessing cough, and second, to investigate the extent to which the results of various assessment methods can be correlated. Methods: Two independent investigators searched the Medline, Embase, and Cochrane databases for validation studies on cough assessment tools. Results: Thirty-four studies were included. Several ambulatory cough monitors automatically identify cough and have been validated in a limited number of patients. Three cough-specific quality-oflife scales (Leicester Cough Questionnaire, Cough Quality of Life Questionnaire, and Burden of Cough Questionnaire) have been validated. No validation studies of descriptive scores or visual analogue scales were found. The correlations between quality-of-life scores and cough frequency were good. The correlations between descriptive scores or visual Received: May 31, 2010 Accepted after revision: August 29, 2010 Published online: November 13, 2010 Sophie Leconte Institut de Recherche Santé et Société, Centre Académique de Médecine Générale Université catholique de Louvain 30 Clos Chapelle-aux-Champs bte 3005, BE–1200 Brussels (Belgium) Tel. +32 2 764 3467, Fax +32 2 764 3435, E-Mail sophie.leconte @ uclouvain.be © 2010 S. Karger AG, Basel 0025–7931/11/0812–0161$38.00/0 Accessible online at: www.karger.com/res D ow nl oa de d by : 54 .1 91 .4 0. 80 9 /1 6/ 20 17 8 :3 4: 24 P M Leconte/Ferrant/Dory/Degryse Respiration 2011;81:161–174 162 measures in these studies have frequently been based on patients’ subjective evaluations of their cough using descriptive questionnaires or visual scales. The validity of these measures is unknown. Therefore, the evaluation of cough by validated methods is a challenge for researchers and clinicians alike. The validity of a measurement instrument is the extent to which it measures what it intends to measure [9] . Therefore, the first issue in cough assessment is to clarify what precisely should be measured. Indeed, the assessment of cough severity can involve several different aspects: (1) the importance of the cough, objectively measured in terms of the frequency or intensity of the expulsive effort; (2) the impact of the cough on the patient’s quality of life, and (3) the importance of the cough, as perceived by the patient. The following assessment tools are currently available: cough monitors used to objectively measure cough frequency, and quality-of-life questionnaires, verbal descriptive scores (VDS), and visual analogue scales (VAS) used to subjectively measure cough severity. In this paper, we consider these 3 facets of cough assessment ( fig. 1 ). The main objective of this systematic review of the literature was to identify the existing validated cough evaluation methods. The second objective was to assess their concurrent validity by investigating the ways in which the results of various cough evaluation methods correlate with one another.