Clinical trial NCT04304586: Clinical Cross Reactions Between Anacardiaceae
Official title: Evaluating the Correlation Between the Results of the Allergy Work-up for Different Allergens of the Anacardiaceae Family
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Suspected Allergy to Anacardiaceae
Keywords: Food allergy
Skin tests
Food challenge
Cashew
Pistachio
Lead sponsor: University Hospital, Montpellier
Sponsor class: OTHER
First posted: 2020-03-11
Enrollment: 100
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: CASE_ONLY
Time perspective: RETROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: All consecutive patients consulting at the Allergy Unit of the University Hospital of Montpellier (France) for a suspected food allergy to Anacardiaceae

Brief summary: The prevalence of food allergies has increased in recent decades, ranging from 1 to 3% of the general population. According to international literature and French national surveys, nuts today represent a group of allergens often associated with severe allergic reactions. They are responsible for 18 to 40% of deaths from food-related anaphylaxis.

Among all nuts, the prevalence of anacardiac allergies (mainly cashew and pistachio) continues to increase and has become a growing public health problem. Today, global production is estimated at 4.9 million tonnes of cashews and 1.1 million tonnes of pistachios. The resulting increased exposure may explain the increased prevalence of allergic reactions reported to these fruits. In addition, anaphylactic reactions to anacardiaceae are reported to be even more severe than those occurring in subjects allergic to peanuts.

Cashews and pistachios are known to exhibit immunological cross-reactions with one another. In fact, they have a strong sequential homology between their storage allergens Ana o 1 / Pis v 3 (7S vicilin, 78% homology); Ana o 2 / Pis v 2 (legume 11S, 80% homology) and Ana o 3 / Pis v 1 (albumin 2S, 70% homology). For this reason, some authors talk about the cashew / pistachio syndrome and associate the two allergenic sources by considering them as one, in clinical practice.

The diagnosis of allergy to nuts, and therefore to anacardiaceae, is based on a compatible clinical history, the presence of specific IgE (demonstrated by positivity to realistic skin tests and serum IgE assay), and positivity on the oral food challenge test.

In clinical practice, taking into account the cashew / pistachio syndrome, when the allergy work-up for cashew is negative, allergists tend to advise to reintroduce pistachio at home, considering the two allergens as sufficiently homologous to authorize such a practice. In this context, the investigators decided to check whether this practice, which is based mainly on in vitro homologies, is risk-free, based on the clinical experience of our center.


Eligibility criteria: Inclusion criteria:

* Patient evaluated at the Allergy Unit of the University Hospital of Montpellier (France)
* Suspicion of food allergy to Anacardiaceae
* Allergy work-up for cashew and pistachio including at least skin tests, and possible specific IgE and food challenge

Exclusion criteria:

- Patients included in other trials that don't allow them to be included in the present one

Primary outcomes:
measure: PPV and NPV
timeFrame: 1 day
Secondary outcomes:
measure: Relative risk
timeFrame: 1 day
Other outcomes:
Locations:
city: Montpellier
country: France
facility: Uhmontpellier
Study officials:
affiliation: University Hospital, Montpellier
name: Davide CAIMMI
role: PRINCIPAL_INVESTIGATOR
References: