Validated methods of cough assessment: a systematic review of the literature

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.

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.

Two independent investigators searched the Medline, Embase, and Cochrane databases for validation studies on cough assessment tools.

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-of-life 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 analogue scales and more objective methods, such as cough frequency monitoring or quality-of-life scores, were inconsistent.

Cough-specific quality-of-life questionnaires can provide valid outcomes for research into cough. Although the current developments in cough monitoring devices are promising, further studies on a larger scale, under more realistic conditions, and for different patterns of cough are required before they can be recommended for widespread use.