Patient-Anchored Cough Visual Analogue Scale and Leicester Cough Questionnaire Thresholds for Cough Control...

The cough severity visual analogue scale (VAS) and the Leicester Cough Questionnaire (LCQ) are commonly used in chronic cough. While continuous scores are useful for tracking change, categorization is needed to define clinically relevant states. However, patient-anchored thresholds for cough control remain undefined.

Using the Korean Chronic Cough Registry (n = 890), we derived VAS and LCQ cutoffs anchored to a patient-reported cough control item. Receiver operating characteristic (ROC) analyses were performed using operational definitions of very well-controlled cough ("strongly agree" vs. all others), well-controlled cough ("strongly agree" + "agree" vs. all others), and uncontrolled cough ("disagree" + "strongly disagree" vs. all others).

Both scores demonstrated stepwise gradients across cough control categories (p < 0.001). ROC-derived cutoffs for very well-controlled cough were VAS ≤ 10 (area under the curve [AUC], 0.911) and LCQ ≥ 15.8 (AUC, 0.877). For well-controlled cough, the corresponding cutoffs were VAS ≤ 30 (AUC, 0.866) and LCQ ≥ 15 (AUC, 0.856). For uncontrolled cough, the cutoffs were VAS ≥ 50 (AUC, 0.879) and LCQ ≤ 13.0 (AUC, 0.872). Cutoffs were consistent across newly referred chronic cough and refractory chronic cough subgroups. Concordance between VAS- and LCQ-derived classifications was moderate-to-substantial (weighted kappa = 0.55).

Based on these findings, we propose a patient-anchored classification framework for cough control: very well-controlled cough (VAS ≤ 10, LCQ ≥ 16), well-controlled cough (VAS 11-30, LCQ 15.0-15.9), intermediate cough control (VAS 31-49, LCQ 13.1-14.9), and uncontrolled cough (VAS ≥ 50, LCQ ≤ 13). These thresholds warrant validation in diverse populations.