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

Area of Science:

• Pulmonology
• Clinical Research
• Patient-Reported Outcomes

Background:

• The visual analogue scale (VAS) is commonly used for assessing cough severity and frequency in chronic cough (CC).
• However, established thresholds for clinically meaningful treatment response using VAS in routine practice are lacking.
• This uncertainty hinders effective patient management and clinical trial interpretation.

Purpose of the Study:

• To determine the minimum clinically important differences (MCIDs) for cough VAS severity and frequency.
• To anchor these MCIDs using real-world data, incorporating objective cough counts and patient-reported quality of life.
• To provide reliable thresholds for evaluating treatment efficacy in CC.

Main Methods:

• A prospective observational study involving 103 patients with CC before and after standard treatment.
• Cough severity and frequency assessed via 100-mm VAS.
• Health-related quality of life measured by the Leicester Cough Questionnaire (LCQ); 24-hour cough frequency (CoFr24) monitored by the Leicester Cough Monitor.
• MCIDs calculated using receiver operating characteristic analyses, anchored to established MCIDs for LCQ and CoFr24.

Main Results:

• VAS severity and frequency showed significant correlations with LCQ and CoFr24.
• Anchor-based analyses consistently identified an absolute MCID of approximately -24 mm for both VAS domains.
• Percentage-based MCIDs converged at a 60-65% reduction, demonstrating good discriminative ability (sensitivity 70-80%, specificity 65-90%).

Conclusions:

• An absolute change of 24 mm and a percentage change of 60-65% reduction in cough VAS represent clinically meaningful improvement in CC.
• These validated thresholds enhance the utility of VAS in clinical practice and research.
• Percentage-based MCIDs offer complementary value across varying baseline cough severities.