Dataset Information

Different definitions of atopic dermatitis: impact on prevalence estimates and associated risk factors.

ABSTRACT:

Background

There is no objective test that can unequivocally confirm the diagnosis of atopic dermatitis (AD), and no uniform clinical definition.

Objectives

To investigate to what extent operational definitions of AD cause fluctuation in the prevalence estimates and the associated risk factors.

Methods

We first reviewed the operational definitions of AD used in the literature. We then tested the impact of the choice of the most common definitions of 'cases' and 'controls' on AD prevalence estimates and associated risk factors (including filaggrin mutations) among children aged 5 years in two population-based birth cohorts: the Manchester Asthma and Allergy Study (MAAS) and Asthma in Ashford. Model performance was measured by the percentage of children within an area of clinical indecision (defined as having a posterior probability of AD between 25% and 60%).

Results

We identified 59 different definitions of AD across 45 reviewed studies. Of those, we chose four common 'case' definitions and two definitions of 'controls'. The prevalence estimates using different case definitions ranged between 22% and 33% in MAAS, and between 12% and 22% in Ashford. The area of clinical indecision ranged from 32% to 44% in MAAS and from 9% to 29% in Ashford. Depending on the case definition used, the associations with filaggrin mutations varied, with odds ratios (95% confidence intervals) ranging from 1·8 (1·1-2·9) to 2·2 (1·3-3·7) in MAAS and 1·7 (0·8-3·7) to 2·3 (1·2-4·5) in Ashford. Associations with filaggrin mutations also differed when using the same 'case' definition but different definitions of 'controls'.

Conclusions

Use of different definitions of AD results in substantial differences in prevalence estimates, the performance of prediction models and association with risk factors. What's already known about this topic? There is no objective test that can unequivocally confirm the diagnosis of atopic dermatitis (AD) and no uniform clinical definition. This results in different definitions utilized in AD studies, raising concerns on the generalizability of the results and comparability across different studies. What does this study add? This study has shown that different definitions of 'cases' and 'controls' have major impacts upon prevalence estimates and associations with risk factors, including genetics, in two population-based birth cohorts. These findings suggest the importance of developing a consensus on AD definitions of both 'controls' and 'cases' to minimize biases in studies.

SUBMITTER: Nakamura T

PROVIDER: S-EPMC6916614 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Project description:ImportanceKnowledge about factors associated with persistence of atopic dermatitis (AD) during childhood is sparse.ObjectiveTo explore heritable, environmental, and clinical factors associated with persistent AD based on 13 years' follow-up of an at-risk birth cohort.Design, setting, and participantsIn the Copenhagen Prospective Study on Asthma in Childhood 2000 (COPSAC2000) clinical birth cohort study, 411 children born to mothers with asthma were followed up until the age of 13 years at a clinical research unit in Copenhagen, Denmark, from August 1998 to June 2015. Atopic dermatitis was diagnosed prospectively during close clinical follow-up according to the criteria of Hanifin and Rajka. Data were gathered on parental history, social circumstances, and environmental factors through parent interviews. The cohort was followed up with biannual visits to the clinic until the age of 7 years and were seen again at age 13 years. Data were analyzed from August 2015 to January 2018.Main outcomes and measuresAtopic dermatitis was diagnosed using Hanifin and Rajka major and minor criteria, and severity was determined by Scoring Atopic Dermatitis (SCORAD) index, with possible scores from 0 to 83, with higher scores indicating more severe AD.ResultsOf the 411 children in the cohort, 203 (49.4%) were male and 186 (45.3%) were diagnosed with AD before the age of 13 years; 40 of 166 children (24.1%) had persistent AD at the age of 13 years, and 126 (76.0%) experienced remission. Factors associated with persistent AD to age 13 years included heritability, environmental exposures, asthma and allergic sensitization, clinical presentation at the time of diagnosis, the composition of Hanifin and Rajka diagnostic minor criteria, and AD severity according to SCORAD. A higher AD genetic risk score was associated with an increased the risk for persistent AD (multivariable odds ratio [OR], 1.8; 95% CI, 1.1-2.9; P = .02), together with paternal asthma (multivariable OR, 3.7; 95% CI, 1.2-11.5; P = .02); paternal AD (multivariable OR, 6.2; 95% CI, 1.17-23.2; P = .007), and higher social circumstances (multivariable OR, 1.6; 95% CI, 1.0-2.5; P = .05). Particular clinical presentations at time of diagnosis were also associated with specific minor criteria of Hanifin and Rajka (Dennie-Morgan and anterior neck folds, white dermographism, intolerance to wool, itching when sweating, tendency to skin infection, food intolerance, and food allergy) (OR, 2.6; 95% CI, 1.1-6.2; P = .03) as well as increased severity at diagnosis (OR, 1.1; 95% CI, 1.0-1.1; P = .007).Conclusions and relevanceIn a birth cohort of children at risk for asthma who received close clinical follow-up to age 13 years, known genetic AD risk variants, paternal asthma and AD, high social circumstances, diagnostic minor criteria, and disease severity at onset were associated with persistent AD at age 13 years. These findings may be applied in clinical practice to evaluate the likely disease course for individual patients.

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