AD Phenotypes: Itch and Lesional Severity

Raj Chovatiya, MD, PhD, is assistant professor of dermatology at the Northwestern University Feinberg School of Medicine in Chicago, IL. Dr Chovatiya also directs the Eczema and Itch Clinic where he focuses on chronic inflammatory skin disease, particularly atopic dermatitis and eczema, but also other chronic inflammatory conditions like psoriasis and hidradenitis. He met with The Dermatologist to discuss one of his recent studies titled “Clinical Phenotyping of Atopic Dermatitis Using Combined Itch and Lesional Severity.”

Dr Chovatiya: Let's take this back to the beginning and talk about atopic dermatitis. As a disease, it's complex, it's heterogeneous, and there's quite a complex combination of signs, symptoms, comorbidities, and even quality of life.

Historically in the clinic of clinicians, we tend to focus a lot on skin lesions when determining AD severity like the standard classification system of mild, moderate, and severe, but we know that atopic dermatitis is more complicated than that.

Let's take itch, for instance. This is the single most burdensome and prevalent symptom among atopic dermatitis patients. Patients frequently tell us about different levels of itch in combination with different severity of their lesions. This idea led us to want to better understand how we can use both signs and symptoms to better clinically phenotype atopic dermatitis.

Over the course of several years, our research team led by Dr. Jonathan Silverberg has been prospectively following hundreds of atopic dermatitis patients. We've been collecting both patient and clinician reported outcomes of severity, itch, and other measures of quality of life.

First, interestingly, we found that measures of itch and then measures of lesional severity only shows somewhere between mild to moderate correlation with each other. Meaning that neither measured alone is describing the whole story.

In our analysis, we classified patients into four different groups based on their itch and based on their lesional severity: People with milder itch and milder lesions, people with milder itch and severe lesions, people with severe itch and milder lesions, and then people with both severe itch and severe lesions.

While more than half of patients in our population with atopic dermatitis had milder itch and milder lesions, the second largest group was patients that had severe itch and mild lesions, almost a quarter of our patients. This is important because this group hasn't been looked at much in previous studies.

Possibly, as clinicians, we often tend to focus on the signs of atopic dermatitis, what we can see as a dermatologist rather than the symptoms themselves.

Even though patients with some form of severe itch and severe lesions were all more likely to describe their disease as being more severe, those specifically with severe lesions and either mild itch or severe itch, were more likely to be categorized as severe by clinicians themselves.

This is important because despite the discrepancy between the patient and clinician evaluation of severity, patients with severe itch and milder lesions, and patients with mild itch and severe lesions, all had very similar increased number of disease flares, sleep disturbances, mental health symptom, limited time spent in disease remission, and overall worse health related quality of life.

We also found that there was a highly dynamic and fluctuating longitudinal course among patients with severe itch. Perhaps more significantly, while most patients with severe lesions and either mild or more severe itch initiated systemic step up therapy, less than one third of people with severe itch, but mild lesions did so.

This number is even lower than people with milder lesions and milder itch. It tells us that we have a lot of work to do here to better understand things, but if we better understand clinical phenotyping in atopic dermatitis, this might allow us to select treatment and predict disease course and outcome better than we already are able to do.

Reference

1. Chovatiya R, Lei D, Ahmed A, Chavda R, Gabriel S, Silverberg JI. Clinical phenotyping of atopic dermatitis using combined itch and lesional severity: A prospective observational study. Ann Allergy Asthma Immunol. Published online April 2, 2021; S1081-1206(21)00220-9. doi:10.1016/j.anai.2021.03.019