Allergy in Children
Allergy tends to be more common in children compared to adults, with asthma, allergic rhinitis, eczema and food allergy comprising a significant proportion of the workload doctors have to deal with in primary care and hospital paediatric departments. It is reported that worldwide, approximately 1 in 8 children have asthma, 1 in 13 have eczema and 1 in 8 have allergic rhinitis.(1) In the UK, these figures are higher when looking at self-reported allergic rhinitis (1 in 5), asthma (1 in 3) and eczema (1 in 6) (2).
Food allergy affects 3-6% of children in the developed world (3). A recent UK study (4) reported a prevalence for food allergy of 7.1% in breast-fed infants, with 1 in 40 developing peanut allergy and 1 in 20 developing egg allergy. Children with early-onset eczema are at an even higher risk of developing food allergy, in particular peanut allergy, with almost 1 in 5 developing peanut allergy by 5 years of age.(5) Cow’s milk allergy is another common allergy, with a similar prevalence to peanut allergy: approximately 1 in 40 children are affected (6). The incidence of cow’s milk allergy in the UK is known to be the highest in Europe, with approximately half of those children suffering from eczema and gastrointestinal symptoms (7). Increases in the prevalence of food allergy are reflected by a documented increase in hospital admission rates of children with very severe reactions (anaphylaxis) in the UK (8).
Allergic diseases are not static. The distribution and pattern of disease changes as the child matures. Infants are more likely to present with atopic eczema, food allergy, gastrointestinal symptoms and wheezing, whilst older children typically present with asthma and allergic rhinoconjunctivitis. These observed differences are frequently referred to as the “allergic march”, which recognises the association between these diseases and the tendency for children to “outgrow” certain aspects of their allergic disease e.g. eczema or milk allergy. Important associations are recognised between eczema and respiratory allergy, between eczema and food allergy and between rhinitis and asthma. 70% of infants with eczema are at risk of developing either asthma or allergic rhinitis. Infants with moderately severe or severe eczema have a 30-50% risk of being food allergic.The risk can further be quantified by the presence or absence of specific IgE (allergy antibodies) to relevant inhalant or food allergens: positive tests to house dust mite and grass pollen at 2 years strongly predicts the development of asthma and allergic rhinitis.
It is important that doctors caring for children with allergic disease recognise that children frequently present with multiple atopic disease, which may only become apparent as the child grows older. Early life events appear to be critical to the likelihood of an individual developing subsequent allergic disease, which means that the management of a child in early life may have far reaching consequences. For this reason there are a number of research programmes underway looking at early intervention strategies for the prevention of allergy.
Central to the optimum management of any child with allergic disease is an understanding of the impact of disease on their lives at school and at home and the consequences of allergic disease on their growth and development. As many children will be multiply allergic with co-existing respiratory, gastrointestinal or skin disease, good allergy management requires a holistic, structured approach with a co-ordinated treatment strategy aimed at maximising the child’s quality of life whilst minimising the potentials side effects of treatment.
1) Pols DH et al. Interrelationships between Atopic Disorders in Children: A Meta-Analysis Based on ISAAC Questionnaires. 2015 Jul 2;10(7)
2) Atopic dermatitis, asthma and allergic rhinitis in general practice and the open population: a systematic review. D. H. J. Pols et al. Scand J Prim Health Care. 2016 Jun; 34(2): 143–150.
3) Rona RJ, Keil T, Summers C, Gislason D, Zuidmeer L, Sodergren E, et al. The prevalence of food allergy: a meta-analysis. J Allergy Clin Immunol 2007;120:638-46.
4) Perkin et al. Randomised trial of introduction of allergenic foods in breast fed infants. NEJM 2016; 374: 1733-1743
5) Du Toit et al. Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy. NEJM 2015; 372: 803-813
6) Grimshaw KE et al. Incidence and risk factors for food hypersensitivity in UK infants: results from a birth cohort study. Clin Transl Allergy. 2016 Jan 26;6
7) Schoemaker et al. Incidence and natural history of challenge-proven cow’s milk allergy in European children – EuroPrevall birth cohort. Allergy 2015
8) Turner et al. Increase in anaphylaxis-related hospitalizations but no increase in fatalities: an analysis of United Kingdom national anaphylaxis data, 1992- 2012. JACI 2015; 135(5); 956-963