Fig. 3

Cough deficiency in relation to the CPF. Cough deficiency was assessed by the Numerical Rating Scale (NRS) ranging from 0 (no difficulty) to 10 (strongest difficulty). To enhance evaluability, groupings were made as follows: 0 = no cough deficiency, 1–3 = mild cough deficiency, 4–6 moderate cough deficiency, 7–10 = severe cough deficiency. n = 596.