Clinically Meaningful Differences for Cough-Specific Visual Analogue Scale in Chronic Cough: A Real-World Study

Cough-specific visual analogue scale (VAS) is widely used to assess cough severity and frequency; however, clinically meaningful thresholds for treatment response in chronic cough (CC) remain uncertain in routine practice.

To determine minimum clinically important differences (MCIDs) for cough VAS severity and frequency using real-world data anchored to both objective cough frequency and patient-reported quality of life.

In this prospective observational study, 103 patients with CC were evaluated before and after standard treatment. Cough severity and frequency were assessed using 100-mm VAS, health-related quality of life using the Leicester Cough Questionnaire (LCQ), and 24-hour cough frequency (CoFr₂₄) using the Leicester Cough Monitor. MCIDs for absolute (ΔVAS) and percentage (%ΔVAS) changes were estimated by receiver operating characteristic analyses, anchored to established MCIDs for LCQ (≥ 1.3-points increase) and CoFr₂₄ (≥ 30% reduction).

VAS severity and frequency showed moderate, statistically significant correlations with both LCQ and CoFr₂₄. Anchor-based analyses consistently identified an absolute MCID of approximately -24 mm for both VAS domains, irrespective of anchor selection. Percentage-based MCIDs converged at a 60-65% reduction. These thresholds demonstrated acceptable discriminative ability (sensitivity of 70-80%, specificity of 65-90%) and remained consistent across objective and patient-reported anchors in a heterogeneous CC population.

In the present study, both ΔVAS of 24 mm and %ΔVAS of 60-65% reduction in cough VAS represented clinically meaningful improvement. Percentage-based MCIDs may complement absolute thresholds across a range of baseline severity, supporting the use of VAS in clinical practice and trials.