There are several scales used to measure the severity of atopic dermatitis (AD). Some of these include the SCORAD (Scoring of Atopic Dermatitis) Index, the ADSI (Atopic Dermatitis Severity Index), and the EASI (Eczema Area and Severity Index). Not all of these scales specifically measure the severity of AD-related intense itching (also called pruritus), and those that do, measure pruritus along with other aspects of AD to create an overall picture of an individual’s condition. Other basic scales, such as a using a basic numerical rating scale of 0 to 10 (with 10 being the most severe itching imaginable) to assess an individual’s pruritus are sometimes used, however, there may be a bias towards individuals choosing numbers near the middle of the scale, preventing accurate measurements of itch severity.1
Adapting the Severity of Pruritus Scale (SPS)
Knowing that there may be a lack in efficient and accurate tools used to assess itch alone, a team of researchers led by Drs. Gil Yosipovitch and Eric Simpson set out to test the validity of a new pruritus severity-measuring scale. Their research, published this June in Itch, the official journal of the International Forum for the Study of Itch (IFSI), outlines a new itch severity-measuring scale, the Severity of Pruritus Scale (SPS) and tests its reliability and validity using a cohort of individuals with AD. Previously, both of these doctors have completed extensive research on the pathophysiology of the AD itch (the mechanisms behind why individuals with AD itch), and the impact of AD on quality of life, among other AD-related topics.2,3
The SPS was derived from the larger ADSI scale, and asks respondents to use only the pruritus-assessing portion of that scale to describe their itching over the past 24 hours. This allows for the collection of data at regular intervals to track the change in itch severity over time. The SPS uses a 4-point scale with a range of 0 to 3. Each number indicates the following itch characteristics over the past 24 hours:
0, None: No itching
1, Mild: Occasional, slight itching/scratching
2, Moderate: Constant or intermittent itching/scratching which is not disturbing sleep
3, Severe: Bothersome itching/scratching which is disturbing sleep1
Testing the SPS
The study tested the clarity, relevance, and appropriateness of the SPS using 14 individuals with AD over the age of two-years-old. Children between the ages of two and seven were able to have a caregiver respond to the SPS for them. These individuals were interviewed in either English or Spanish, depending on what language was most comfortable for them, and the researchers observed any questions they had using the scale and any difficulties they had in interpreting the SPS options. Additionally, the SPS was further investigated using data from two large US-based, phase 3 clinical trials evaluating the use of topical crisaborole (Eucrisa). Over 1,500 participants ages two and older with AD completed the SPS twice daily for 29 days using an electronic diary.1
A new tool for measuring itch
The results from the qualitative (in-person interview-based) and the quantitative (data-based) portions of the study indicated that the SPS was reliable, valid, and able to detect changes in pruritus, making it a favorable test for assessing AD-related itching.1 Overall, the addition and use of a tool like the SPS designed to specifically measure pruritus severity and its changes may be beneficial in assessing the efficacy of treatment options designed to reduce the itch, which is often reported as one of the most quality of life-impacting symptoms of AD.
Yosipovitch G, Simpson EL, et al. Assessment of pruritus in atopic dermatitis: Validation of the Severity of Pruritus Scale (SPS). Itch. June 2018; 3, e13.
Yosipovitch G, Papoiu AD. What causes the itch in atopic dermatitis? Curr Allergy Asthma Rep. Jul 2008; 8(4), 306-11.
Simpson EL, Bruin-Weller M, et al. When does atopic dermatitis warrant systemic therapy? Recommendations from an expert pane; of the International Eczema Council. J Am Acad Dermatol. Oct 2017; 77(4), 623-33.