D2.29 - Use and knowledge of Phadiatop Infant and Fx5 in children from a primary care healthcare area

Phadiatop Infant (PhadInf, indicated for children ≤5 years old) and Fx5 are in vitro screening tests detecting IgE antibodies to common inhalant/food allergens, and food allergens, respectively. Both demonstrated clinical usefulness and cost-effectiveness as first-line screening tools in primary care pediatric settings. Notwithstanding, its frequency of use and referral patterns are poorly known.

Objective: To assess the frequency of use of PhadInf and Fx5 in children from a primary care area and their impact on referrals for allergy consultation.

A retrospective real-world observational study was conducted, analysing all requests for Phadiatop, Phadiatop Infant, and FX5 (Thermo Fisher Scientific, Uppsala) from June 2021 to June 2023 in the Salamanca health area. Results ≥0.35 P_AU/L were considered positive. Collected data included patient demographics, requesting specialty, and referral for allergy consultation. For referred patients, final diagnoses were obtained from clinical records. Requests for Phadiatop in ≤5 years were recorded.

Whereas 596 Phadiatop tests were requested during this period, including 11 in children ≤5 years, PhadInf was demanded in 15 patients (median age 4.4 years; 26.6% female; 80% ≤5 years old). PhadInf was positive in 7 (38.9%), mainly from primary care (72.2%); five were referred. In children ≤5 years of age, PhadInf was positive in 5 cases (41.7%). No patients with negative results were referred. Final diagnoses were food sensitization (2), allergic rhinoconjunctivitis (1), exclusion of food allergy (1), and a non-allergic genetic disorder (1). Among children ≤5 years undergoing Phadiatop testing, 2/11 were positive, but none were referred to the Allergy Department.

Fx5 was requested in 25 patients ≤14 years, 13 ≤5 years old (median age 7 years; 32% female). Four (16%) had positive results; three were referred and diagnosed with fish-induced enteropathy, food-related eosinophilic esophagitis, and seafood allergy. Six patients with negative FX5 were referred; pollen allergy was diagnosed in three, food allergy was excluded in two, and one patient did not attend.

Phadiatop Infant and Fx5 were infrequently used as first-line screening tests for IgE-mediated sensitization in children, suggesting limited familiarity with these tests.In addition, 20% of PhadInf requests were made for children >5 years,reflecting inappropriate test use. Strategies are needed to improve awareness and appropriate utilization.