Table 2:

Overview of itch-related PRO measures.

Measure	Description
WI-NRS	11-point scale of itch intensity over the previous 24-h period (range 0 to 10; higher scores indicate greater itch intensity), which has been validated in patients with CKD-aP [40, 42, 43]. Reduction of ≥3 points on the WI-NRS has been shown to be associated with a clinically meaningful change in itch intensity for patients with moderate-to-severe pruritus undergoing HD [43].
SADS	SADS categorizes patients into one of three self-designated types (A, B or C), depending on the presence of scratch marks on the skin, the impact of itching on sleep, and the presence of agitation/sadness due to itching [40, 41].
Skindex-10	Multidimensional tool to evaluate the impact on itch-related QoL of CKD-aP across three separate itch-related domains: Disease, Mood/Emotional Distress and Social Functioning [65]. Skindex-10 total scores range from 0 to 60, with worsening itch-related QoL indicated by higher scores. Analysis of Phase 2 clinical trial data in adult HD patients with moderate-to-severe pruritus indicated that a ≥15-point reduction (improvement) from baseline in the total Skindex-10 score represents a clinically meaningful change [52].
5-D itch	Multidimensional tool that assesses itch-related QoL and itch intensity across five separate itch-related domains (Duration, Degree, Direction, Disability and Distribution) over a 2-week recall period [44]. 5-D itch scale total scores range from 5 to 25, with worsening itch intensity and itch-related QoL indicated by higher scores. Analysis of Phase 2 clinical trial data indicates that a clinically meaningful improvement was represented by a reduction from baseline of ≥5-point in the total 5-D itch score [52].
Sleep Quality Numerical Rating Scale	11-point scale to indicate how much itch interfered with sleep over the preceding 24 h, with responses ranging from 0 (“did not interfere”) to 10 (“completely interfered”).
Patient self-categorization of pruritus severity	Patients 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).
MOS sleep scale	6-point scale ranging from “all of the time (0)” to “none of the time (6)” to indicate the frequency of various aspects of sleep disruption. Also records estimates of average hours of sleep during the past week and length of time taken to fall asleep. Higher scores reflect better sleep-related HRQoL.
PGI-S	Single-item scale with five possible values ranging from none to very severe to assess patient impression of itch severity; higher scores reflect worse severity.
PGI-C	Single-item measure with values ranging from “1” (Very Much Improved) to “7” (Very Much Worse); higher scores reflect worse status to assess patient impression of change (improvement or worsening) in overall status relative to the start of the study.
M-PGIC	Single-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” to assess patients’ overall impression of change in itch during the course of the clinical trial and whether the amount of improvement was meaningful to them.
Dermatology Life Quality Index	10 questions concerning patients’ perception of the impact of skin diseases on different aspects of their HRQoL over the last week, calculated by summing the score of each question resulting in a maximum of 30 and a minimum of 0. The higher the score, the more quality of life is impaired [45].

HRQoL, health-related quality of life; MOS, Medical Outcomes Study; PGI-S, Patient Global Impression of Worst Itch Severity; PGI-C, Patient Global Impression of Change; M-PGIC, modified Patient Global Impression of Change.