Estimating the prevalence of aero-allergy and/or food allergy in infants, children and young people with moderate-to-severe atopic eczema/dermatitis in primary care: multi-centre, cross-sectional study.

OBJECTIVE: We sought to determine the primary care-based prevalence of moderate-to-severe atopic eczema/dermatitis in children and to estimate what proportion had co-morbid aero-allergy and/or food allergy that was contributing to their atopic eczema/dermatitis.

DESIGN: Multi-centre, cross-sectional study.

PARTICIPANTS: Infants, children and young people aged between 0-17 years.

SETTING: Primary Care.

METHODS: General practice electronic health records were interrogated to identify children (0-17 years) with current moderate-to-severe atopic eczema/dermatitis. Eligible children were assessed by an allergy specialist nurse, this involving a detailed allergy history, examination and, if appropriate, measurement of total IgE and specific IgE to relevant aero-allergens and/or food allergens.

MAIN OUTCOME MEASURES: Prevalence of atopic eczema, moderate to severe atopic eczema, IgE-mediated atopic eczema.

RESULTS: We recruited eight practices, which together enrolled 16,877 children. Of these, 4331 (25.7%; 95% CI 25.0, 26.3) children had a recorded diagnosis of atopic eczema/dermatitis and 1316 (7.8%; 95% CI 7.4, 8.2) had treatment indicative of current moderate-to-severe atopic eczema/dermatitis. We recruited 159 children for clinical assessment, and complete data were available for 157. The clinical assessment revealed that 130/157 (82.8%) had no indication of IgE-mediated allergy contributing to their atopic eczema/dermatitis; the remaining 27/157 (17.2%; 95% CI 12.1, 23.9) were on clinical assessment considered to possibly have underlying IgE-mediated disease. Specific IgE tests were positive in 14/27 (51.9%; 95% CI 34.0, 69.3) children. Of the 14 children who tested positive, six (42.9%; 95% CI 21.4, 67.4) were positive to food allergens and six (42.9%; 95% CI 21.4, 67.4) to aero-allergens; the remaining two (14.3%; 95% CI 4.0, 40.0) were positive to both food and aero-allergens.

CONCLUSIONS: Although atopic eczema/dermatitis is a very common diagnosis in children in primary care, most appear to be relatively mild and/or transient. Only a small proportion of children had evidence of ongoing underlying IgE-mediated atopic eczema/dermatitis.