Which test is best for diagnosing peanut allergy in South African children with atopic dermatitis?

• Published in: South African medical journal 2016-02, Vol.106 (2), p.214-220
• Main Authors: Gray, Claudia Liesel, Levin, Michael E, Du Toit, George
• Format: Article
• Language: English
• Subjects: Care and treatment; Children; Complications and side effects; Dermatitis; Diagnosis; Immunoglobulin E; Inflammation; Medical tests; Patient outcomes; Skin
• ISSN: 0256-9574
• DOI: 10.7196/SAMJ.2016.v106i2.10125

Diagnosing peanut allergy based on sensitisation alone leads to an unacceptable rate of overdiagnosis. To define parameters that may help differentiate peanut allergy from asymptomatic sensitisation in a cohort of South African (SA) children with atopic dermatitis (AD). It is the first study in SA to utilise oral food challenge tests and analyse peanut component patterns. This was a prospective, observational study at a paediatric university hospital in Cape Town, SA. Children with AD, aged 6 months - 10 years, were recruited randomly. They were assessed for sensitisation and allergy to peanut by questionnaire, skin-prick tests (SPTs), immuno solid-phase allergen chip (ISAC) tests, ImmunoCAP component tests to Ara h 1, 2, 3, 8 and 9, and incremental food challenges. One hundred participants (59 Xhosa (black Africans) and 41 of mixed race, median age 42 months) were enrolled. Overall, 44% of patients were peanut sensitised and 25% had a true peanut allergy. SPTs and ImmunoCAP Ara h 2 produced the highest areas under the receiver operating characteristic curve for predicting peanut allergy in peanut-sensitised patients. The ISAC test was less sensitive, more specific and produced significantly lower median values than ImmunoCAP tests. Ara h 2 was the most useful component in differentiating allergy from tolerance in both ethnic groups, being positive in 92% of allergic and 40% of sensitised but tolerant children (p