Study of the Prevalence of Food Allergens in Patients with Allergies Admitted to Mofid Chil ‐ dren ’ s Hospital During 2010 to 2016

Introduction: Allergic diseases include a wide range of symptoms such as asthma, rhinitis, urticaria, eczema, and gastrointestinal symptoms that are becoming increasingly prevalent in today’s world. Exposure to food allergens is one of the contributing factors for allergic diseases in humans. The identification of susceptibility to food allergens plays an important role in the prevention and treatment of allergic diseases. Materials and Methods: After the clinical diagnosis of allergic diseases, patients were examined using the skin prick test.The method of collecting data was observational. All data were entered in SPSS software version 21 and analyzed using descriptive and inferential statistics. Results: A total of 466 patients with a mean age of years were studied, of which 58.6% were boys and 41.4% were girls. A total of 44.2% patients had asthma, 21.7% had allergic rhinitis, 2.1% had allergic sinusitis, 1.7% had conjunctivitis, 1.1% had angioedema, 11.6% had urticaria, 19.7% had eczema, and 26.8% had gastrointestinal allergic symptoms. A total of 114 patients (24.5%) had food allergies, of which 43.9% were girls and 56.1% were boys. In terms of the age and gender of patients, no statistically significant difference was observed between different food allergens (P<.05). The most common allergens in patients under study were peanuts (7.9%), milk (7.3%), almond (6.6%), freshwater fish (6.6%), and walnuts (6.4%). Conclusion: The findings revealed that allergen prevalence in each region is influenced by its climatic conditions, people’s food habits, their racial differences, and their lifestyles.


INTRODUCTION
An allergy refers to an instant reaction of the immune system that occurs when the immune system responds to allergens that re-enter the body after it was already stimulated earlier by them (1).In recent years, for various reasons, different types of allergic diseases have spread throughout the world (2).After the re-entry of allergens into the body, the immune system responds to them and high levels of immunoglobulin E (IgE) are produced by B lymphocytes.IgE synthesis is because of immediate hypersensitivity as a result of Th2 cell activation and cytokine secretion of Interleukin (IL)-4, IL-5, IL-9 and IL-13.In allergic reactions, IL-4, which is a cytokine, plays an important role with its antitumor and anti-inflammatory effects, and immune responses are increased by IgE.Following the production of IgE, IL-4 is placed on mast cells and basophiles,and it binds with specialized receptors Fcε.If IL-4 is reconnected to the allergens, it activates them,causing the release of inflammatory mediators, which in turn gives rise on the types of symptoms include atopic dermatitis, allergic rhinitis, and asthma (8).Asthma is the most common chronic disease, that is, in fact, caused by chronic reversible airway obstruction.Its symptoms include coughing, shortness of breath, and wheezing.It can be seen at any age, but the peak incidence occurs at 3 years.This disease occurs twice as much in boys compared with girls during childhood.However, in adults, it is seen in both sexes equally (9).Allergic rhinitis is a common disease observed in different parts of the world (10).This disease has a prevalence of 10% to 40% in different age groups of the general population.Its clinical symptoms mainly and classically include sneezing, itching, and stuffy and runny nose (11).The cause of this disease is unknown, but factors such as hereditary and environmental factors are responsible for this disease.Allergic rhinitis is seasonal in 20% of cases, 40% permanent, and 40% combined (12).Atopic dermatitis is one of the atopic skin diseases that mostly occurs in childhood, and about 15% of the world's children suffer fromthis disease (13).The onset of symptoms of the disease in 50% of the cases occurs during the first year of life and 30% during 1 to 5 years (14).
Chronic urticaria is a vascular reaction that appears with symptoms such as erythematous inflation with white color and transient itching (15).In 10% to 40% of cases, chronic urticaria is caused due to an autoimmune response.In about 50%, the cause of acute urticaria is unclear.About 20% to 40% of acute urticaria progresses to chronic or recurrent urticaria (16).Angioedema is the swelling of the skin, subcutaneous tissue, mucosa, and submucosa.It is very similar to urticaria; however, it affects deeper tissues.Usually, in angioedema, the face, lips, mouth, and tongue swell within a few minutes to a few hours; sometimes hands, throat, and digestive tract are also affected.Such symptom scan also be observed in the case of itching edema but are less than in those with urticaria (17).In general, food allergens may play a role in earlier start and increase of allergic diseases in some patients (18), and they may impact the quality of life of people, especially patients with allergies (19).So now, because of changes in the pattern of these allergens in different communities and regions, identifying food allergens in allergic diseases is of great importance (20).There are also various reports of the prevalence of food allergens in allergic diseases in different geographical regions and ages in Iran (21,22).One of the standard methods to identify the allergens is the skin prick test that is a reliable method for the diagnosis of allergic diseases related to IgE.This method is less invasive, inexpensive, and reproducible, and the results are quickly available (23).
Considering the different food allergens in different geographical conditions and ages, as well as their importance in prevention of allergic diseases, this study was designed to investigate the prevalence of food allergens using the skin prick test in patients with allergies admitted to the super specialty clinic of asthma and allergy for children in Mofid Children's Hospital during 2010 to 2016.

MATERIALS AND METHODS
We conducted a descriptive-sectional study in the super special clinic of children in Mofid Hospital at Shahid Beheshti University of Medical Sciences, Tehran.The studied population consisted of children with allergic diseases admitted to the super clinic of asthma and allergy during the years 2010 to 2016.A total of 466 children were selected as sample.In fact, statistical population wasequal to all available forms of prick test results available in the clinic.The data were recorded in a made-up checklist based on the available documents in children's clinical files and the availability of the prick test results according to the determining initial factors such as age, gender, and type of allergic disease.A total of 44 different types of allergens qualified for the study.The skin prick test was performed on those patients.In this test, histamine was used as a positive control, and normal saline was used as a negative control.Common food allergens (Greer Co. America) were studied in 6 groups, including eggs (yolks and whites), dairy (cow's milk), meat (beef, lamb, chicken, and shrimp), nuts (walnuts, hazelnuts, peanuts, and almonds), fruits (bananas, grapes, strawberries, kiwi, watermelon, and honeydew melon), and cereals (wheat, soybeans, barley and rice).To run the test, extracts of allergens were placed in front of the wrist and at a distance of 2 cm from each other.Then skin scrape was done with a lancet (bloodless) at the place of allergen, and the test result was determined and compared with the control group after 20 minutes.The skin test was considered positive if the redness spread in more than 15 mm region of the wrist, and if there was a swelling of more than 3 mm, the test was considered negative.After getting the results of the skin prick test in the form of children's information, data were analyzed using SPSS version 21.In analyzing the data, descriptive statistics factors were used to describe the current situation, and the chi-square test and Fisher exact test were used to compare food allergy by age groups, gender, and type of allergic disease.

RESULTS
The study included 466 children with allergic diseases admitted to the super special clinic of asthma and allergy for children in Mofid Hospital during 2010 to 2016.The aim of this study was to determine the prevalence of food allergens in these children.
Results indicated that the mean age of children with allergic diseases under study was 7.4 ± 4.09 years, ranging from 1 to 18 years.In terms of gender, 273 patients (58.6%) were male, and 193 patients (41.4%) were female.
The distribution of age groups in patients with a variety of allergic diseases is summarized in Table 2.In general, children aged 7 years and older, in terms of allergic diseases, had a higher prevalence than other age groups.
Results show that 114 patients (24.5%) had food allergies, of which 50 patients (43.9%) were female and 64 (56.1%) were male.In patients with the negative food allergen skin test, 143 patients (40.6%) were female and 209 patients (59.4%) were male.There was no significant difference between the positive skin prick test and the gender of patients (P=.585).
The data in Table 3 show that in patients with food allergy, 15 (13.2%) were less than 3 years of age, 27 patients (23.7%) were between 7 and 3 years of age, and 72 patients (55.6 %) were 7 years of age and older.While in patients with the negative food allergen skin test, 46 (13.1%) were less than 3 years of age, 119 patients (33.8%) were between 7 and 3 years of age, and 187 patients (53.1%) were 7 years of age and older.There was no significant difference between the skin prick test in terms of the age groups of patients (P=.112).
The prevalence of a variety of food allergens in different allergic diseases is given in Table 4. Data show that peanuts (7.9%), milk (7.3%), almond (6.6%), freshwater fish (6.6%), and nuts (6.4%) were the most common food allergens in patients who were under investigation.

DISCUSSION
According to the findings, it was revealed that from the total of 114 patients, 28 (24.5%) had food allergies; 50 patients     (43.9%) were female and 64 (56.1%) were male.Statistically, there was no meaningful difference between the positive skin prick test with gender and age groups of patients (P=0.112).This finding is consistent with research findings of Onsori and colleagues.The results of their study showed that among 282 patients with atopic dermatitis, 87 patients (31%; 52 females and 35 males) were sensitive to at least 1 food allergens (prick test, positive), and there was no meaningful difference between gender and food allergy in patients with atopic dermatitis.In people with atopic dermatitis with food allergies, asthma, allergic rhinitis, and urticaria were, respectively, 6.8, 11.4, and 4.5.The most common food allergens in patients were yolk (38.4%), egg white (36.5%), hazelnuts (33.3%), and peanuts (28.7%), and the least common were rice (4.6%), barley (5.7%), and sheep meat (6.9%).Eggs and nuts were the most common allergens, especially for children (24).
Other findings of the present study showed the prevalence of food allergy in patients under study.A total of 47 patients (41.2%) with asthma, 24 patients (21.1%) with allergic rhinitis, 4 patients (3.5%) with conjunctivitis, 2 patients (1.8%) with angioedema, 13 patients (11.4%) with urticaria, 28 patients (24.6%) with eczema, and 34 patients (29.8%) with allergic gastrointestinal symptoms had food allergies as confirmed by the skin prick test.

CONCLUSION
Finally, according to the findings of the present study, the authors concluded that the prevalence of allergens in each area is under the influence of climatic conditions of each region, people's habits and food, racial differences, and different lifestyle.So the identification of allergens, avoiding them, selection of conscious food diet, along with drug therapy, play an important role in the treatment of children with allergic diseases.

Table 1 .
Comparison of the age distribution of patients by type of allergic diseases in children admitted to the clinic of asthma and allergy for children in mofid hospital during 2010 to 2016

Table 2 .
Comparison of the distribution of age group percentage by the type of allergic disease in children admitted to the clinic of asthma and allergy for children in mofid hospital suring 2010 to 2016

Table 3 .
Comparison of the distribution of age group percentage based on the food allergen prick skin test results of children admitted to the clinic of asthma and allergy for children in mofid hospital during 2010 to 2016

Table 4 .
Comparison of the frequency percentage distribution of food allergens based on types of allergic diseases in children admitted to the clinic of asthma and allergy for children in mofid hospital during 2010 to 2016