The Many Ways to Measure the Severity of Atopic Dermatitis

— Validated physician-reported tools are often complicated, but patient-based measures are easy and informative

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Illustration of four circles with atopic dermatitis over an arm with atopic dermatitis falling down onto the arm

"Medical Journeys" is a set of clinical resources reviewed by physicians, meant for the medical team as well as the patients they serve. Each episode of this 12-part journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.

In the United States, the management of atopic dermatitis requires physicians to document the severity of the disease in compliance with individual payer requirements for coverage of medication and other prescribed treatments. The most commonly used instruments to capture these data include such physician-reported measures as the Eczema Area and Severity Index (EASI) score, the SCORing AD (SCORAD) index, and the Investigator Global Assessment (IGA). In clinical practice, the extent of affected body surface area may be all that is required.

Many of the validated tools used primarily in clinical trials may be too time-consuming for routine clinical practice. These physician-based instruments rely on visual assessment of clinical signs and don't capture patient symptoms such as itchiness and skin pain or how these impact sleep. And despite initiatives by the Harmonizing Outcome Measures for Eczema (HOME) group and others to develop a standardized set of assessment tools for clinical practice, many measurement tools overlook the heterogeneity of atopic dermatitis, particularly in adults.

"Clinicians will need to consider advantages and shortcomings of the available tools when choosing which to use routinely in the clinic," wrote Anna Fishbein, MD, of Northwestern University Feinberg School of Medicine in Chicago, and colleagues in a 2019 update on atopic dermatitis diagnosis, severity assessment, and treatment in the Journal of Allergy and Clinical Immunology.

While the EASI score and the SCORAD index are recommended, "we all know that they are really not practical for clinical use unless you have a lot of help from someone who knows how to use them," said Amy Paller, MD, also of Northwestern Feinberg, where she is chair of the Department of Dermatology and director of the Skin Biology and Diseases Resource-Based Center.

One of the biggest issues with severity scoring tests is that they provide a cross-sectional assessment, noted Jonathan Silverberg, MD, PhD, director of clinical research at George Washington University School of Medicine and Health Sciences in Washington, D.C. "They're assessing a short-term level of control, whether it's a 3-day, 7-day, or 30-day recall period. Very few of them do a good job of looking at longer-term control."

Silverberg estimated that there are more than 80 severity assessment tools for atopic dermatitis. "Practitioners really need to decide what fits best into their practice setting, what information they need to get for their payers in order to get coverage for medications, and what is most relevant for their own patients," he told MedPage Today. "I don't think there's any one-size-fits-all approach."

Elaine Siegfried, MD, director of Pediatric Dermatology at SSM Health Cardinal Glennon Children's Hospital in St. Louis and professor of Pediatrics and Dermatology at Saint Louis University School of Medicine, agreed: "There are many, many factors that go into deciding whether a patient is a good candidate for systemic treatment," she told MedPage Today. "You can't always get to those with these kind of pre-defined instruments."

Patient-Reported Outcome Measures

Dermatology experts emphasize the importance of asking patients about atopic dermatitis-related symptoms, and note that the use of specific patient-reported outcome measures can provide a more complete picture of the overall burden of disease, in a very efficient way.

It's still important to find out what's behind the numbers, Siegfried emphasized. "Is it sleep, is it pain, is it school absenteeism, is it social?"

A 2021 assessment of three patient-reported outcomes measures in adults with moderate to severe symptoms of atopic dermatitis showed that the Itch Numeric Rating Scale (Itch NRS), the Skin Pain NRS, and the Atopic Dermatitis Sleep Scale (ADSS) all had "good to excellent" reliability, validity, and responsiveness. All three could be used by patients to chart disease severity on a daily basis, the researchers noted in Health and Quality of Life Outcomes.

Patient-reported outcome measures such as the Atopic Dermatitis Control Tool (ADCT) are helpful for assessing long-term disease control, said Lawrence Eichenfield, MD, vice-chair of the Department of Dermatology at the University of California San Diego School of Medicine. "It is important to consider recording the extent and severity of atopic dermatitis in moderate to severe disease, as this helps with evaluations over time," he told MedPage Today.

Paller said she also uses the six-measure ADCT score for patients on maintenance therapy, since it's fairly straightforward and patients find it easy to use. "You can print out the questionnaire, have the patients complete it, and get a score," she explained.

The subjective data captured by patient-reported outcome measures can be particularly valuable when it comes to quantifying the severity of itch, which is also a marker of long-term disease control. A 2019 study highlighted the gap between itch severity scores provided by patients compared with physicians.

Adults with moderate to severe itch symptoms were asked: "On a scale of 0 to 10, with 0 being 'no itch' and 10 being 'worst itch imaginable,' how would you rate your itch at the worst moment during the previous 24 hours?" Trial participants, almost two-thirds of whom came into the study reporting 12 or more hours of severe to unbearable itching every day, were tasked with rating itch severity for 16 weeks using the 11-point single-item Peak Pruritus NRS. A change of ≥ 2 to 4 points in the Peak Pruritus NRS was considered clinically relevant.

The Peak Pruritus NRS scores had only a weak to moderate correlation with physician-based outcome measures such as EASI and IGA. By comparison, there was a moderate to high correlation between the Peak Pruritus NRS scores and other patient-related outcome measures such as the itch visual analogue scale of SCORAD, and the itch item of the Dermatology Life Quality Index (DLQI).

Notably, there was a moderate to strong correlation between changes in Peak Pruritus NRS and other patient- and clinician-reported outcome measures. This finding supports the responsiveness of the Peak Pruritus NRS to changes in itch severity, the researchers said.

More recently, following a validation study of the multiplied product of two scores -- the IGA and the affected percentage of body surface area (BSA) -- investigators concluded that the IGA×BSA score provides a practice-friendly option for measuring the severity of symptoms in atopic dermatitis. Previously, a post hoc analysis of data from the PRISTINE and PRESTA trials had indicated that the composite tool was a simple alternative to the Psoriasis Area and Severity Index for the assessment of psoriasis.

Using the EASI score as the standard for accuracy in the assessment of atopic disease severity, the IGA×BSA correlated highly with EASI, but was much simpler to perform in a busy office setting. Suggested severity strata for IGA×BSA was:

  • 0-30 for mild atopic dermatitis
  • 30.1-130 for moderate atopic dermatitis
  • 130.1-400 for severe atopic dermatitis

"The IGA is 0 to 4, and the BSA is 0 to 100%, so the levels are very simple," said Paller, one of the co-authors of the validation study. "It's really easy, and I'm using it in my own practice now."

The 7-point patient-oriented eczema measure (POEM) is also easy to perform, she added. "Just give it to the patient or caregiver, and ask them to fill it out. It just takes a minute. Then you can quickly look at it and see where their levels are."

Paller said that for time and convenience, she typically reaches for the itch NRS: "I find out the patient's worst itch score, their average, and ask how they're sleeping. These are the tools that I always use in my practice because I think they're telling."

Read previous installments in this series:

Part 1: Atopic Dermatitis: Reasons for Optimism

Part 2: Atopic Dermatitis: The Latest on Diagnosis and Assessment

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    Kristin Jenkins has been a regular contributor to MedPage Today and a columnist for Reading Room, since 2015.