Study of Gefapixant (MK-7264) in Acute Cough for Participants With Induced Viral Upper Respiratory Tract Infection (URTI) (MK-7264-013)

Change From Baseline in the Cough Severity Visual Analog Scale (VAS) Score on Day 3

The Cough Severity VAS was scored from 0 to 100 using a 100 mm visual analogue scale. Participants were asked to mark on a 100 mm scale between 0 (no cough) and 100 (the worst cough severity). Cough VAS was evaluated at Baseline and on Day 3.

Time frame: Baseline and Day 3

Change From Baseline in the Mean Total Daily Cough Severity Diary (CSD) Score on Day 3

The Mean Total Daily CSD Score is calculated using the daily CSD instrument, a 7-item, disease-specific, patient-reported outcome measure with a recall period of "today" (the current day). The measure evaluates frequency of cough (3 items); intensity of cough (2 items); and disruption due to cough (2 items). Each of these 7 items is rated on an 11-point scale, ranging from 0 (best) to 10 (worst), with higher scores indicating greater severity. The total daily CSD score is the sum of these 7 item scores (Min=0, Max=70). The Mean Total Daily CSD Score (the sum of these 7 item scores divided by 7) was calculated at Baseline and on Day 3.

Time frame: Baseline and Day 3

Change From Baseline in the Leicester Cough Questionnaire (LCQ)-Acute Score on Day 3

The LCQ-Acute is a 19-item health-related quality-of-life (HRQoL) questionnaire specific for acute cough which contains three domains (i.e., physical, psychological, and social). It is calculated as a mean score for each domain ranging from 1 to 7, and total score ranging from 3 to 21. Each item on the LCQ-acute assesses symptoms or the impact of symptoms on HRQoL in the last 24 hours using a 7-point Likert scale ranging from 1 to 7. Higher scores indicate better HRQoL. Participants' perception of their cough severity was assessed, based on the LCQ-Acute score, at Baseline and on Day 3.