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Míriam Araújo1, Gonçalo Martins-dos-Santos1, Inês Sangalho1, Sofia Ferrito2, Elena Finelli1, Sara Prates1, Paula Leiria Pinto1,3

1- Serviço de Imunoalergologia, Hospital Dona Estefânia, Centro Hospitalar Universitário de Lisboa Central, Lisboa
2 - Serviço de Pediatria, Hospital Garcia de Orta, Almada
3 - CEDOC, Integrated Pathophysiological Mechanisms Research Group, Nova Medical School, Lisbon, Portugal

- EAACI Anual Congress, Junho 2020
- 41ª Reunião Anual da SPAIC, Setembro 2020; 2º prémio

Background: Few studies suggest that siblings of children with food allergy are at higher risk of developing food allergy. Parents are usually anxious about the risk of food allergy in siblings, but due to the lack of clear evidence it is difficult for clinicians to elucidate them about this possibility. We sought to determine the prevalence of confirmed food allergy among siblings of children with diagnosed food allergy.
Method: Retrospective analysis of pediatric population with confirmed IgE-mediated food allergy in our outpatient clinic between 2010 and 2015. Through telephonic interviews with the parents, we evaluated the presence of confirmed food allergy among siblings, culprit food, other atopic diseases and subjective level of anxiety of the parents.
Results: From 525 patients we were able to contact 279, of which 76% (n=209) had siblings. In 45% of this population the index child was the older sibling. The most prevalent allergies in the index child were egg (49%; n=102) and milk (43%; n=90), followed by nuts (19%; n=40), fish (18%; n=37), fresh fruits and crustaceous (15%; n=32 and n=31, respectively). Only 15% (n=32) of the siblings had confirmed food allergy. The most common culprit foods in siblings were milk and egg, such as in the group of index children. Among the allergic siblings, 66% (n=21) had the same allergy as the index child, being milk the most common (n=9).
Attempted prevention of food allergy with measures like avoidance or late introduction was not tried in most cases. From the 13% (n=27) who did it, around 2/3 were due to having an allergic sibling. Thirty eight percent of parents reported anxiety when introducing food to a younger sibling (n=57/151).
Conclusion: According to our results, prevalence of food allergy in siblings of food allergic children seems to be low, although higher than what is usually reported for the general pediatric population. Nonetheless, and even though the culprit food is often the same as in their brother or sister, clinicians should elucidate the parents that trying to prevent food allergy through measures like avoidance or late introduction in younger siblings is not recommended and can even lead to the development of allergy, being counter-productive. Further studies are needed to corroborate these results and conclusions.