Defining "Flares" in Atopic Dermatitis: A Narrative Review.

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by fluctuating disease activity. Exacerbations of AD signs and/or symptoms, or flares, have a significant impact on patient quality of life and may require modification or escalation of treatment. However, research into preventing and managing flares may be hampered by the lack of consensus on a clear, clinically relevant, measurable definition of flare. This narrative review provides an overview of disease flare frameworks established through previous systematic literature reviews, flare definitions proposed by American and European guidelines, as well as those used in randomized controlled trials and observational studies published between January 2014 and September 2024. It identifies a range of flare definitions in use in the literature, the majority of which are based on clinician-reported outcomes, with very few referring to the patient perspective. Given the highly individualized experience of disease flare in patients with AD, incorporating the perspective of patients, alongside established measures of disease activity, is vital for creating and validating a definition that is clinically relevant.