الفهرس 
Epidemiology of food allergyOnly 14 pages are availabe for public view
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Abstract
Food allergy is one of the most common causes of allergic diseases, it can be the cause of respiratory allergic disease, gastrointestinal allergic diseases, and dermatological allergic diseases.
The community is over estimating the true prevalence of food allergy, as a great percent of people claims to have allergic reaction after consuming some types of food, giving misleading history of food allergy makes the accurate diagnosis of food allergy difficult to be achieved.
The pathological types of food allergy are divided into mainly two types, IgE mediated (which is immediate in onset) and non IgE mediated which has late onset in addition to third mixed group.
The IgE mediated food allergy has the benefit of being immediate onset (2 hours max), so it is easy for the patient to correlates his symptoms with food consumption, on other hand the late onset of non IgE mediated (up to two days) makes it difficult for the patient to detect the causative food that even the patient may not correlates his symptoms with food consumption in the first place.
IgE mediated allergic reaction in general is easy and simply diagnosed by detailed history, skin prick test , and measurement of specific IgE in the patient ’s serum, while in diagnosis of non IgE mediated allergy history is not always clear, skin prick test has no rule in the diagnosis, and serum IgE level analysis also is not helpful.
from the previous concepts the idea of creating a simple, non invasive test can be performed in the outpatient clinic, has been existed in medical field, and the results was the atopy patch test, in which, the prolonged continuous exposure to the allergen factor leading to cellular reaction in the sensitized patients with cellular infiltration leading to solid results which can be positive or negative and the positivity can be graded as well.
The atopy patch test is performed by applying the antigen in direct contact with the patient ’s skin for 2 to 3 days, giving time to inflammatory cells to react to the antigen and form the suitable inflammatory reaction ranging from, redness, redness with infiltration, papule, up to vesicles, according to the severity of the case.
As previously mentioned the test is outpatient clinic test, easy to perform and well tolerated by the patients, saving time, effort, and resources.
This study was conducted on 60 patients . The selected patients were recruited from the Allergy and Clinical immunology outpatient clinic at Ain Shams University Hospitals. in addition to 20 healthy volunteer as control group
All patients and the control group ,were subjected to: Full medical history taking, Clinical examination, Skin prick test, Serum total IgE by ELISA, atopy patch test, food elimination test, and open oral food challenge test.
In our study we observed the following:
In case group 40 (67%) of them had history of Urticaria, 14 (23%) had history of Rhinitis, 10 (17%) had history bronchial asthma and 2 (3%) had history of gastrointestinal manifestations.
77% of the case group gave history of perceived food allergy Milk, strawberry, spice and fish were the most common types of food allergy by history.
38% patients with serum total IgE >100 and among the control group, there were 20% subject with serum total IgE >100.
The skin prick test results was 48% positive in the case group and 15% positive in the control group, the most common foods which gave positive results are banana, solanaceae, egg and milk this results iis accepted as SPT in not 100% accurate and specific.
The atopy patch test results was positive in (62%)of the case group and no positive results was detected in the control group, the most common food which gave positive results are egg, strawberry , solanaceae and fish.
Out of the 60 cases there were 48 (80%) positive for Food Elimination Test and 45 (75%) cases were positive for open Food Challenge test.
The statical analysis of the results of the atopy patch test gave that the Sensitivity of APT was 69%, Specificity was 60%, Positive Predictive Value was 84%, Negative Predictive Value was 30% and the accuracy of APT was 67%.
In conclusion the atopy patch test showed a satisfactory results to be used in the diagnose non IgE mediated food allergy as it showed high specificity and high positive predictive value which makes it a good positive test. This will save time and efforts to decrease the burden for both the physicians and the patients. Making the diagnosis of non IgE mediated allergic diseases much easier and accurate, and shorten the treatment journey for allergic patiens.