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

BACKGROUND

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.

OBJECTIVES

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.

METHODS

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).

RESULTS

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.

CONCLUSIONS

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.