Because atopic dermatitis (AD) may be a lifelong condition, improving the measurement of the frequency and duration of active disease intervals can help to define clearer the clinical course of atopic dermatitis and how treatment impacts long-term results.
“Improved measurement of the frequency and duration of active disease periods can help to elucidate more about the initial course of atopic dermatitis and the role of treatment in long term outcomes,” write Katrina Abuabara, M.D., of the University of California, San Francisco, and colleagues in an article in Dermatologic Clinics. “Because atopic dermatitis is episodic, its incidence, prevalence, persistence, remission, flare and long-term control require careful definition.”
Atopic dermatitis studies that are limited to children may underestimate the average age of disease onset by excluding adult onset cases. Likewise, studies that favor patients with more persistent and severe disease that manifests earlier in life may not be representative of the general atopic dermatitis population.
Existing data is unable to determine if atopic dermatitis permanently resolves, in part because studies differ in their definition of clearance (ranging from 11% to 92%).
Although some children and young adults seem to improve with age from prior treatment with a topical calcineurin inhibitor, most of these patients continue to have active disease multiple times.
“Longitudinal studies that follow individuals throughout adulthood are needed to better understand the periodicity of disease activity and patterns over the life course,” the authors write.
There is scant consensus as to the causes of atopic dermatitis onset or progression. It is also unclear whether treating AD influences the long-term clinical course or prevents the development of comorbid conditions.
The authors propose the following five concepts, accompanied by methodological considerations and recommendations, to study the long-term course of atopic dermatitis.
Incidence, which must by chronic to meet most diagnostic criteria, along with a specified minimum duration of symptoms for diagnosis (4 weeks has been suggested)
Prevalence, which is dependent on the time period and the definition, along with a specified method of assessing, such as a physical examination versus self-reporting, and the definition used.
Remission/Persistence, which is predicated on the length of follow-up and the method of detection. But the authors dissuade using the term “remission,” due to the episodic nature of the condition and the complexities of defining inactive disease. Still, they recommend noting the age of the patient and duration of follow-up without treatment and/or symptoms.
Flare, which is dependent on the patient’s baseline, but is challenging to determine the exact duration. One recommendation is to combine a patient-reported outcome with a severity score or a behavioral measure like “escalation of treatment.”
Long-term control, for which there is no agreement on measurement. Nonetheless, clearly define “long-term control” and consider the number of totally and well-controlled weeks to assess long-term control of atopic dermatitis.
Katrina Abuabara MD, David J.Margolis MD, PhD, Sinéad M.Langan FRCP, PhD. "The Long-Term Course of Atopic Dermatitis," Dermatologic Clinics. Volume 35, Issue 3, July 2017, Pages 291-297.