Table 1.

Patient-reported outcome measures

Measure	Response scale	Recall period	References
WI-NRS (Worst Itching Intensity Numerical Rating Scale)	Worst itching experienced on 11-point scale: 0–10. “0” labelled with the anchor phrase “no itching” and “10” labelled “worst itching imaginable”	24 h	[13, 14]
Skindex-10	10 questions with a 7-point scale: 0–6. “0” labelled with the anchor phrase “never bothered” and “6” labelled “always bothered”. Total score is sum of the numeric value of each answered question (range, 0–60). Total score is subdivided into three domain scores that are sums of the scores of the following questions: disease domain (questions 1–3 with score range from of 0 to 18); mood/emotional distress domain (questions 4–6 with score range of 0–18); and social functioning domain (questions 7–10 with score range of 0–24)	Past week	[8]
5-D itch	Five dimensions assessed: degree (k = 1), duration (k = 1), direction (k = 1), disability (k = 4), and distribution (k = 16). Degree, duration, direction and disability domains measured by a five-point Likert scale with higher scores reflecting worse itch. Disability domain includes four items that assess itching impact on daily activities: sleep, leisure/social activities, housework/errands and work/school; disability domain score is highest score on any of the four items. For distribution domain, number of affected body parts is tallied (sum, 0–16) and the sum sorted into five scoring bins: sum of 0–2 = score of 1, sum of 3–5 = score of 2, sum of 6–10 = score of 3, sum of 11–13 = score of 4, and sum of 14–16 = score of 5. Scores of each of the five domains summed together to obtain a total 5-D score ranging from 5 (no pruritus) to 25 (most severe pruritus)	Past 2 weeks	[26]
Patient self-categorization of pruritus severity	Patients asked to select which of three patient profiles they are most like according to occurrence of scratch marks on skin, problems sleeping because of itching, and feelings of agitations or sadness: Patient A (mild signs and symptoms), Patient B (moderate signs and symptoms), or Patient C (severe signs and symptoms)	Current	[8]
MOS sleep scale	For most questions, 6-point scale: 1–6. “1” labelled with the anchor phrase “all of the time” and “6” labelled “none of the time” indicating the frequency of various aspects of sleep disruption. Instructions also provided to estimate average hours of sleep during the past week and length of time taken to fall asleep. Sleep Problem Index II (k-9; items 1, 3, 4, 5, 6, 7, 8, 9, 12), Sleep Problem Index I (k-6; items 4, 5, 7, 8, 9, 12), and Sleep Disturbance (k = 4; items 1, 3, 7, 8) subscales can also be calculated. Higher scores reflect better sleep-related HRQoL	Past week	[27]
PGI-S (Patient Global Impression of Worst Itch Severity)	Assesses patient impression of itch severity. Single-item scale with five possible values ranging from none to very severe; higher scores reflect worse severity	24 h	[28]
PGI-C (Patient Global Impression of Change)	Assesses patient impression of change (improvement or worsening) in overall status relative to the start of the study. Single-item measure with values ranging from ‘1’ (Very Much Improved) to ‘7’ (Very Much Worse); higher scores reflect worse status	Current vs. earlier time point	[28]
M-PGIC (modified Patient Global Impression of Change)	Assesses patients’ overall impression of change in itch during the course of the clinical trial and whether the amount of improvement was meaningful to them. Brief, one-item measure with four response options: “My itch got worse,” “No change,” “My itch got better but the amount of improvement was not meaningful to me,” and “My itch got better and the amount of improvement was meaningful to me”	Current vs. earlier time point	[28]

Missing data were handled according to the instructions provided by the instrument authors. Abbreviations: HRQoL, health-related quality of life; MOS, Medical Outcomes Study