Assessing Performance of Psoriasis, Atopic Dermatitis Questionnaires Over Time

Researchers investigated whether responses to questionnaires on psoriasis and atopic dermatitis prevalence remained consistent over time.

When asked about a history of atopic dermatitis, cohort study participants’ responses were inconsistent over time, while those of patients asked about a history of psoriasis showed considerable agreement, according to research published in JAMA Dermatology.

“This inconsistency suggests that questionnaires on a history of atopic dermatitis will confer considerable risk of bias and misclassification,” the authors wrote.

Although some of the studies' findings have suggested increasing psoriasis prevalence among different populations, results differ based on data collection methods and not all studies have yielded the same finding. In addition, the prevalence of atopic dermatitis can be difficult to determine due to the disease’s episodic nature.

Because several countries do not consistently collect health care data in registries, questionnaire-based studies are often carried out when it comes to measuring the prevalence of these 2 diseases.

To investigate whether adult patients change their responses to these questionnaires over time, the researchers sought to assess test-retest accuracy of asking individuals about a history of psoriasis and of atopic dermatitis for prevalence estimations.

A total of 10,000 adults aged 18 or older randomly selected from the Danish Civil Registration System were recruited to take part in the Danish Skin Cohort. Of these, 3490 were interviewed between May and July 2018 and asked the following 2 questions: “Has a doctor ever told you that you have or have had psoriasis?” and “Has a doctor ever told you that you have or have had atopic dermatitis?”

Between October and November 2020, participants were asked the exact same questions in the same format. A total of 2333 individuals completed the psoriasis questionnaire in 2018 and 2020. Individuals had a mean (SD) age of 55.1 (16.2) years in 2018, and the majority (57.4%) were women.

A total of 2312 individuals completed the atopic dermatitis questionnaire both years. These individuals had a mean age of 55.0 (16.2) years in 2018 and the same proportion were women.

Researchers used Cohen κ to investigate the test-retest reliability.

Analyses revealed:

  • Among participants reporting a history of psoriasis, agreement between individual responses was high (κ = 0.7558)
  • Among those reporting a history of atopic dermatitis, agreement was low (κ = 0.4395)
  • For psoriasis, prevalence changed from 7.8% to 8.0%; for atopic dermatitis, from 8.2% to 7.6%
  • Of participants who in 2018 reported atopic dermatitis diagnosed by a dermatologist, 36.9% claimed in the 2020 questionnaire that they had never had atopic dermatitis
  • Analyses revealed substantial agreement for psoriasis responses across all age strata
  • For atopic dermatitis responses, the κ declined with increasing age, to 0.2613 for participants 65 or older

“Many of the participants who in 2018 reported being diagnosed with atopic dermatitis by either a nondermatologist-physician (66.7%) or a dermatologist (36.9%) claimed in 2020 that they had never had atopic dermatitis, highlighting the unreliability of using such questions to assess atopic dermatitis prevalence through surveys,” the authors said.

They were unable to follow-up to identify reasons behind individuals’ responses, marking a limitation to the study. The atopic dermatitis questionnaire could have also performed poorly as the clinical presentation of the disease in adulthood may be less clear.


Nymand LK, Anderson YMF, Thyssen JP, Egeberg A. Limitations of using questionnaires for assessing the prevalence of psoriasis and atopic dermatitis among adults. JAMA Dermatol. Published online July 7, 2021. doi:10.1001/jamadermatol.2021.2307