GENEVA (FRONTLINE MEDICAL NEWS) – The prevalence of atopic dermatitis (AD) among adults ages 18-65 years varies across countries in North America, Europe, and Asia, and regionally within those countries as well, according to an unprecedented eight-country survey of roughly 90,000 subjects.

The web-based survey included roughly 20,000 U.S. respondents along with 10,000 from each of seven other countries: Italy, Spain, France, Germany, United Kingdom, Canada, and Japan. Most prior studies have focused on pediatric AD, Laurent Eckert, PhD, observed at the annual congress of the European Academy of Dermatology and Venereology.

The prevalence of adult AD was highest in Italy (8.1%) and Spain (7.2%), followed by the United States (4.9%), France (3.6%), Canada (3.5%), United Kingdom (2.5%), Germany (2.2%), and Japan (2.1%). Other investigators had previously reported a lower figure for the United States: 3.2% versus the 4.9% found in the new international survey, noted Dr. Eckert, an epidemiologist at Sanofi in Chilly-Mazarin, France.

The United States was the only country in which the prevalence of AD was higher in men than women, albeit by the narrow margin of 5.1% versus 4.9%. The rate was similar in men and women in the United Kingdom, and significantly greater in women in the other six participating countries. For example, the male:female prevalence ratio in Canada was 3.0%:4:0%, while in Italy it was 6.0%:10.0%.

Some degree of regional variability in the prevalence of AD was seen within each country. The biggest regional differences were seen within Italy and France. “The regional variability within Italy was in accord with a previous study that showed higher rates in Mediterranean regions relative to those in a more northern, continental climate,” Dr. Eckert said.

Two-stage criteria had to be met to label a respondent as having AD in this web-based survey. The participant had to be positive on the basis of the U.K. Working Party’s diagnostic criteria for AD ( Br J Dermatol. 1994 Sep;131[3]:406-16 ), the key element of which is an affirmative answer to the question, “In the past 12 months, did you ever have an itchy rash that was coming and going for at least 6 months?” And the subject also had to self-report having received a physician diagnosis of AD.

Dr. Eckert and his coinvestigators employed three different validated methods of assessing AD severity: Physician Global Assessment, the Patient-Oriented Eczema Measure, and the Patient-Oriented Scoring AD. These three methods yielded wide variability in the distribution of individuals labeled as having severe AD. The Physician Global Assessment categorized 3%-8% of adult AD patients as having severe disease, depending upon the country, while the Patient-Oriented Eczema Measure yielded a 9%-17% prevalence of severe disease, and Patient-Oriented Scoring AD rated 12%-21% of adults with AD as having severe disease.

“The variability is severity distribution based on the outcome measure used suggests a need for standardization of severity assessment,” Dr. Eckert said.

In most countries, the peak prevalence of adult AD occurred in the 35- to 44-year-old age group, then fell steadily. In the United States, however, the peak came a decade earlier: The prevalence was 4.5% among 18- to 24-year-olds, it was 7.2% in the 25-34 age bracket, and it declined to 6.0% at age 35-44, 3.8% at 45-54, and 2.7% among 55- to 65-year-olds.

Dr. Eckert was also first author of a new study of the burden of adult AD in the United States. The study, which analyzed health care resource utilization data from the 2013 National Health and Wellness Survey, showed that the cost burden of adult AD was comparable to that of psoriasis, although adults with AD had more emergency department visits and higher rates of asthma and other atopic comorbidities ( J Am Acad Dermatol. 2017 Oct 7. pii: S0190-9622[17]32181-3. doi: 10.1016/j.jaad.2017.08.002. [Epub ahead of print] ).

The international survey was supported by Sanofi, which markets dupilumab with Regeneron.


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