Psychometric evaluation of the Worst Pruritus Numerical Rating Scale (NRS), Atopic Dermatitis Symptom Scale (ADerm-SS), and Atopic Dermatitis Impact Scale (ADerm-IS)

Figures & data

Table 1. Content and scoring for the three target questionnaires.

Questionnaire	Rating scale	Item	Frequency	Subscales
Worst Pruritus NRS	0–10 NRS	Itch	Daily (24-h recall period)	Worst Pruritus NRS: weekly average (range 0–10)*
ADerm-SS	0–10 NRS	1) Itch while asleep	Daily (24-h recall period)	ADerm-SS Skin Pain: weekly average of Item 3 (range 0–10)* ADerm-SS TSS-7:^† sums Items 1–7 (range 0–70)
		2) Itch while awake
		3) Skin pain
		4) Skin cracking	Weekly (24-h recall period)
		5) Skin cracking pain
		6) Dry skin
		7) Skin flaking
		8) Rash
		9) Skin thickening
		10) Bleeding
		11) Oozing
ADerm-IS	0–10 NRS	1) Difficulty falling asleep	Daily (24-h recall period)	ADerm-IS Sleep:^‡ sums Items 1–3 (range 0–30)
		2) Sleep impact
		3) Waking up at night
		4) Household activities	Weekly (7-day recall period)	ADerm-IS Daily Activities:^‡ sums Items 4–7 (range 0–40)
		5) Physical activities
		6) Social activities
		7) Difficulty concentrating
		8) Self-conscious		ADerm-IS Emotional State:^‡ sums Items 8–10 (0–30)
		9) Embarrassed
		10) Sad

Abbreviations. ADerm-IS, Atopic Dermatitis Impact Scale; ADerm-SS, Atopic Dermatitis Symptom Scale; NRS, Numerical Rating Scale; TSS-7 7-Item Total Symptom Score; TSS-11, 11-Item Total Symptom Score.

*Score requires at least four ratings over 7-day period.

^†To avoid repeated measurement of concepts potentially assessed by other instruments in clinical trials, the ADerm-SS TSS-7 was developed by summing items that assess concepts not measured by clinician-reported questionnaires; there is a scoring for ADerm-SS TSS-11 which sums all items (scores range from 0–110).

^‡These domain scores are based on and supported by exploratory and confirmatory factor analyses.

Table 2. Score distribution of target assessments at Baseline (N = 882).

Domain	Adults (n = 769)	Adolescents (n = 113)
Worst Pruritus Numerical Rating Scale (WP-NRS; continuous 0–10)
N	769	113
Mean (SD)	7.5 (1.8)	6.9 (2.3)
Median	8.0	7.0
Range	0.0–10.0	0.0–10.0
Atopic Dermatitis Symptom Scale (ADerm-SS)
ADerm-SS Skin Pain (continuous; 0–10)
N	769	113
Mean (SD)	6.4 (2.3)	6.3 (2.4)
Median	6.7	6.7
Range	0.0–10.0	0.0–10.0
ADerm-SS TSS-7* (continuous; 0–70)
N	738	111
Mean (SD)	46.8 (14.0)	44.6 (14.5)
Median	48.0	47.0
Range	0.0–70.0	1.0–70.0
Missing/No response, n (%)	31 (4.0%)	2 (1.8%)
Atopic Dermatitis Impact Scale (ADerm-IS)
ADerm-IS Sleep (continuous; 0–30)
N	769	113
Mean (SD)	18.7 (7.5)	16.7 (8.2)
Median	20.0	18.0
Range	0.0–30.0	0.0–30.0
ADerm-IS Daily Activities (continuous; 0–40)
N	738	111
Mean (SD)	23.8 (10.5)	20.4 (10.8)
Median	25.0	21.0
Range	0.0–40.0	0.0–40.0
Missing/No response, n (%)	31 (4.0%)	2 (1.8%)
ADerm-IS Emotional State (continuous; 0–30)
N	738	111
Mean (SD)	20.2 (7.9)	17.9 (8.7)
Median	22.0	19.0
Range	0.0–30.0	0.0–30.0
Missing/No response, n (%)	31 (4.0%)	2 (1.8%)

Abbreviations. ADerm-IS, Atopic Dermatitis Impact Scale; ADerm-SS, Atopic Dermatitis Symptom Scale; NRS, Numerical Rating Scale; WP-NRS, Worst Pruritus Numerical Rating Scale.

*The ADerm-SS TSS-7 is calculated as the sum of Items 1–7, for the date on which weekly Items 4–7 are collected.

Table 3. Internal consistency reliability for ADerm-SS TSS-7 item scores for Week 16.

Item content	ADerm-SS TSS-7
	Adults	Adolescents
	(n = 637)	(n = 96)
Overall internal consistency	0.97	0.96
When item is deleted:
Item 1 (itch sleep)	0.97	0.95
Item 2 (itch awake)	0.97	0.95
Item 3 (skin pain)	0.97	0.95
Item 4 (skin cracking)	0.97	0.95
Item 5 (skin cracking pain)	0.97	0.95
Item 6 (dry skin)	0.97	0.94
Item 7 (skin flaking)	0.97	0.95

Abbreviations. ADerm-SS, Atopic Dermatitis Symptom Scale; TSS-7, 7-Item Total Symptom Score.

Table 4. Internal consistency reliability for ADerm-IS multi-item scores for Week 16.

Item content	ADerm-IS		ADerm-IS		ADerm-IS
	Sleep		Daily Activities		Emotional State
	Adult	Adolescent	Adult	Adolescent	Adult	Adolescent
	(n = 637)	(n = 96)	(n = 637)	(n = 96)	(n = 637)	(n = 96)
Overall internal consistency	0.99	0.96	0.96	0.95	0.93	0.93
When item is deleted:
Item 1 (difficulty falling asleep)	0.99	0.92	–	–	–	–
Item 2 (impact on sleep)	0.98	0.98	–	–	–	–
Item 3 (waking at night)	0.99	0.92	–	–	–	–
Item 4 (household activities)	–	–	0.95	0.92	–	–
Item 5 (physical activities)	–	–	0.95	0.92	–	–
Item 6 (social activities)	–	–	0.95	0.93	–	–
Item 7 (concentration)	–	–	0.96	0.95	–	–
Item 8 (self-consciousness)	–	–	–	–	0.94	0.96
Item 9 (embarrassment)	–	–	–	–	0.87	0.85
Item 10 (sadness)	–	–	–	–	0.90	0.89

Abbreviation. ADerm-IS, Atopic Dermatitis Impact Scale.

Table 5. Test-retest reliability of the ADerm-SS, ADerm-IS and Worst Pruritus NRS scores between Baseline and Week 2 for participants who reported “no change” on PGIC.

Questionnaire and score	Adults			Adolescents
	n*	Reliability (ICC)^†	95% CI	n*	Reliability (ICC)^†	95% CI
Worst Pruritus Numerical Rating Scale
Item score	165	0.568	0.057, 0.785	35	0.684	0.311, 0.851
Atopic Dermatitis Symptom Scale
Skin Pain score	165	0.645	0.084, 0.839	35	0.764	0.409, 0.896
TSS-7	158	0.592	0.124, 0.792	34	0.547	0.176, 0.765
Atopic Dermatitis Impact Scale
Sleep domain score	165	0.728	0.185, 0.882	35	0.795	0.600, 0.896
Daily Activities domain score	158	0.670	0.244, 0.833	34	0.642	0.383, 0.806
Emotional State domain score	158	0.653	0.293, 0.811	34	0.660	0.293, 0.836

Abbreviations. ADerm-IS, Atopic Dermatitis Impact Scale; ADerm-SS, Atopic Dermatitis Symptom Scale; CI, confidence interval; ICC, intraclass correlation coefficient; NRS, numerical rating scale; PGIC, Patient Global Impression of Change; TSS-7 , 7-Item Total Symptom Score.

*Only subjects with the scores completed at both study visits were included in the analysis.

^†The ICC was computed using the single measurement, absolute agreement, two-way mixed effects model.

Table 6. Pearson correlation on change scores of the ADerm-SS, ADerm-IS, and Worst Pruritus NRS and other supportive measures from Baseline to Week 16.

Assessment	Worst Pruritus NRS	ADerm-SS		ADerm-IS
		Skin Pain	TSS-7	Sleep	Daily Activities	Emotional State
Adults (n = 634)
DLQI: Total score	0.636	0.633	0.655	0.615	0.737	0.655
EQ-5D VAS	−0.331	−0.392	−0.377	−0.353	−0.382	−0.262
PGIS	0.672	0.603	0.663	0.546	0.598	0.573
POEM: Total score	0.676	0.624	0.711	0.548	0.569	0.550
SCORAD-itch	0.807	0.685	0.765	0.635	0.612	0.600
SCORAD-sleep	0.604	0.578	0.648	0.729	0.637	0.571
SCORAD total	0.634	0.542	0.629	0.536	0.520	0.486
EASI: total score	0.387	0.358	0.391	0.390	0.369	0.320
Adolescents (n = 95)
DLQI: Total score	0.566	0.565	0.493	0.772	0.661	0.654
EQ-5D VAS	−0.191	−0.180	−0.186	−0.249	−0.222	−0.291
PGIS	0.460	0.466	0.491	0.496	0.370	0.453
POEM: Total score	0.697	0.650	0.679	0.554	0.421	0.466
SCORAD-itch	0.794	0.733	0.765	0.613	0.468	0.611
SCORAD-sleep	0.519	0.486	0.506	0.642	0.508	0.397
SCORAD total	0.643	0.549	0.610	0.525	0.355	0.434
EASI: total score	0.376	0.270	0.265	0.208	0.161	0.113

Abbreviations. ADerm-IS, Atopic Dermatitis Impact Scale; ADerm-SS, Atopic Dermatitis Symptom Scale; DLQI, Dermatology Life Quality Index; EASI, Eczema Area and Severity Index; EQ-5D VAS, EQ-5D Visual Analog Scale; NRS, numerical rating scale; PGIS, Patient Global Impression of Severity; POEM, Patient-Oriented Eczema Measure; SCORAD, Scoring Atopic Dermatitis; TSS-7 , 7-Item Total Symptom Score.

Table 7. Summary of meaningful within-person change and between-groups differences.

Target questionnaire scores	Adults				Adolescents
	Within-person change		Between-groups difference		Within-person change		Between-groups difference
	PGIS	vIGA-AD	MCID1*	MCID2^†	PGIS	vIGA-AD	MCID1*	MCID2^†
Worst Pruritus NRS (0–10)	−2.47	−3.25	0.82	1.07	−2.27	−2.86	0.97	1.07
	(2.13)	(2.51)			(2.57)	(1.99)
ADerm–SS Skin Pain (0–10)	−2.80	−3.50	1.14	1.36	−2.01	−2.79	1.19	1.32
	(2.45)	(2.65)			(2.99)	(2.70)
ADerm–SS TSS–7 (0–70)	−18.53	−23.68	6.99	8.93	−14.74	−15.96	7.23	9.88
	(16.09)	(18.25)			(25.15)	(16.61)
ADerm–IS Sleep (0–30)	−8.34	−10.61	3.76	3.92	−3.72	−5.71	4.09	4.40
	(7.22)	(8.21)			(7.85)	(7.44)
ADerm–IS Daily Activities (0–40)	−10.48	−13.55	5.26	6.04	−4.89	−12.15	5.40	7.92
	(9.75)	(11.62)			(13.23)	(10.51)
ADerm-IS Emotional State (0-30)	−7.91	−10.68	3.94	4.64	−4.16	−8.07	4.35	5.13
	(7.68)	(8.97)			(10.51)	(8.06)

Abbreviations. ADerm-IS, Atopic Dermatitis Impact Scale; ADerm-SS, Atopic Dermatitis Symptom Scale; PGIS, Patient Global Impression of Severity; TSS-7 , 7-Item Total Symptom Score; vIGA-AD, validated Investigator Global Assessment for Atopic Dermatitis.

*MCID1 = 1/2 Standard Deviation.

^†MCID2 = Standard Error of Measurement.