Application and measurement properties of the visual analog scale in paediatric cough assessment: A systematic review

To describe the operational characteristics of visual analogue scales (VAS) used to assess paediatric cough and to evaluate their measurement properties according to the target construct and reporter.

We conducted a systematic review of PubMed, Embase, and Web of Science from inception to 30 November 2025. Studies were eligible if they included children and applied a VAS to assess cough or cough-related outcomes, reporting assessment characteristics or measurement properties. Data on assessed constructs, scale format, assessor type, timing, and setting were extracted descriptively. Measurement properties were defined in accordance with COSMIN.

18 studies from six countries were included. VAS was most commonly used to assess cough severity, followed by cough frequency and cough-related impact or bother. Scale formats, anchors, reporters, recall periods, assessment timing, and settings varied considerably. For cough severity, both proxy- and child-reported VAS showed sufficient hypotheses testing for construct validity, and the available responsiveness results were also sufficient. For cough frequency, criterion validity was sufficient for proxy report but insufficient for child self-report. For cough-related impact or bother, proxy-reported reliability was insufficient, whereas proxy-reported responsiveness and child-reported hypotheses testing for construct validity were sufficient.

VAS provides a simple approach to paediatric cough assessment, but current evidence is strongest for cough severity and remains limited by inconsistent construct definition and reporter-dependent performance. A standardized core approach, with a clearly specified construct, recall period, scale format, and reporter strategy, would improve interpretability and cross-study comparability.