Chronic cough has a high global prevalence and it is refractory to such treatments by approximately 20% of patients. Gafapixant is a P2X3 receptor antagonist that has demonstrated the reduction of cough in patients with refractory chronic cough(RCC). Taste disturbance is the most frequent adverse event by gefapixant (approximately 60-70%). Although gefapixant is well-tolerated even if taste disturbance has occurred, the impact of taste disturbance on cough-specific QoL remains to be unclear. Therefore, the investigator would like to evaluate factors related to treatment satisfaction by gefapixant in RCC patients. the investigator hypothesize that taste disturbance will be associated with the improvement of cough specific QoL and treatment satisfaction in RCC patients.