CLINICAL RESEARCH e-ISSN 1643-3750 © Med Sci Monit, 2018; 24: 1902-1911 DOI: 10.12659/MSM.908365 Received: 2017.12.04 Accepted: 2018.03.19 Prevalence of Self-Reported Food Allergy in Published: 2018.04.01 Six Regions of Inner Mongolia, Northern China: A Population-Based Survey Authors’ Contribution: BCEF 1 Xiao-Yan Wang 1 Department of Allergy, Beijing Shijitan Hospital, Capital Medical University, Study Design A AB 1 Yan Zhuang Beijing, P.R. China Data Collection B 2 Department of Epidemiology and Statistics, Institute of Basic Medical Sciences Statistical Analysis C BDF 1 Ting-Ting Ma Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Data Interpretation D CD 2 Biao Zhang Medical College, Beijing, P.R. China Manuscript Preparation E ADEFG 1 Xue-Yan Wang Literature Search F Funds Collection G Corresponding Author: Xue-Yan Wang: e-mail: [email protected] Source of support: This study was approved by the National Key Specialty Program and Beijing Municipal Administration of Hospital Incubating Program PX2017020 Background: The aim of this study was to determine the prevalence of self-reported food allergy in 6 regions of Inner Mongolia, northern China. Material/Methods: A random cluster sampling population study using a field questionnaire was distributed to 4714 individuals in 6 regions within Inner Mongolia, northern China; the study included ethnic Mongol minorities and Chinese Han populations. The questionnaire obtained data on ethnicity, age, sex, level of education, income, socioeco- nomic status, rural versus urban location, medical and family history, and food allergy. Results: There were 4441 (73.5%) completed questionnaires. The prevalence of self-reported food allergy was 18.0% (15.2% men; 20.6% women) and was age-related, being significantly greater in children compared with adults (38.7% vs. 11.9%) (P<0.001). There was a significant difference in self-reported food allergy between rural and urban populations (14.6% vs. 21.4%) (P<0.001) and between Mongolian and Han populations (20.8% vs. 15.8%) (P<0.001). Socioeconomic status, higher education level, and increased family income were significantly cor- related with the prevalence of food allergy (P<0.001). Participants with allergic diseases and atopic family his- tory were at increased risk (OR>1, P<0.001). There were no significant associations between the prevalence of food allergy and birth history, infant feeding, and duration of breastfeeding. Conclusions: An increase in the prevalence of self-reported food allergy was found in the Inner Mongolia region of northern China, which was greater in urban areas compared with rural areas. MeSH Keywords: Food Hypersensitivity • Prevalence • Risk Factors • Self Report • Socioeconomic Factors Full-text PDF: https://www.medscimonit.com/abstract/index/idArt/908365 3315 4 2 40 Indexed in: [Current Contents/Clinical Medicine] [SCI Expanded] [ISI Alerting System] This work is licensed under Creative Common Attribution- [ISI Journals Master List] [Index Medicus/MEDLINE] [EMBASE/Excerpta Medica] NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) 1902 [Chemical Abstracts/CAS] Wang X.-Y. et al.: Prevalence of self-reported food allergy… CLINICAL RESEARCH © Med Sci Monit, 2018; 24: 1902-1911 Background Stratifed cluster random sampling in six areas in northem China (Erenhot, Xilinhot, Duolum, Jarud, Food allergy is defined as an immune-mediated reaction to cer- Kailu, Tongliao) tain foods or components of foods [1,2]. Adverse reactions to food were first reported in the 16th century and included re- Field-interview and questionnaire in actions to dietary fish and egg, but food allergy is now known 2015 from May to August (n=4714) to be prevalent worldwide and has recently been shown to be increasing [3]. Epidemiological studies in developed countries have shown that between 1.4% and 33% of the population re- ported adverse reactions to food [4–8]. Food allergy has been Valid questionnaire (n=4441) Invalid questionnaire (n=273) associated with a negative psychosocial impact, anxiety, im- paired quality of life, and is also a cause of cases of anaphy- Final subjects in analysis laxis in patients who present to hospital emergency depart- (n=4441) with 2121 male and 2320 female ments [6,9,10]. Food allergy is associated with a broad array of signs and Figure 1. Flowchart of the study design of a population-based symptoms that may involve the skin, gastrointestinal tract, re- survey of 6 regions of Inner Mongolia, northern China, spiratory tract, and cardiovascular system [11]. The common from May 2015 to August 2015. risk factors for food allergy include childhood age, female gen- der, comorbidity with atopic diseases, industrialized lifestyle, the 2010 national population census. Figure 1 illustrates the and overuse of antibiotics [12,13]. The diagnosis of food al- study design using a flowchart. lergy requires a detailed and reliable patient history and the results of allergen testing, including the skin prick test, the al- Field interview study lergen-specific IgE (sIgE) antibody test and, if indicated, oral food challenges. In population-based studies, allergen test- In each area, different districts were selected as sampling ing has been unavailable in most cases, and so self-reported units. The interviewers consisted of allergists and investiga- prevalence is frequently used in these studies [4,6,7,14]. Due tional staff who were trained before the study commenced. to reporter bias, self-reported prevalence of food allergy may The standard procedure flowchart (Figure 1) was applied for be exaggerated, however, the consensus is that when auxil- each investigational site. The selected participants were noti- iary tests are not available, then self-reported prevalence of fied by telephone or face-to-face meeting and were attended food allergy could be an appropriate tool to evaluate the prev- at the investigational site. The questionnaire was completed alence in a population-based study [1,15]. by the participants or by the parents, if the participants were <18 years of age. The prevalence of food allergy is well documented in developed countries and appears to be increasing, but the prevalence re- Approval to conduct this study was granted by the institu- mains unknown in most emerging countries [11,16]. Currently, tional review boards of Beijing Shijitan Hospital, The Affiliated there is limited population-based information on the preva- Hospital of the Beijing Capital Medical University, and of all 6 lence of self-reported food allergy in China. Therefore, the aim participating municipalities. All participants signed a written of this study was to determine the prevalence of self-report- informed consent before the interview. ed food allergy in 6 regions of Inner Mongolia, northern China. Study questionnaires Material and Methods The participants were required to complete a specially de- signed questionnaire during the field interview by themselves, Study population or by their parents if they were <18 years of age. Data on de- mographic information, family history, past medical disease A cross-sectional epidemiological survey was conducted in history, allergic disease history (including allergic rhinitis, al- Inner Mongolia, northern China, between May 2015 to August lergic conjunctivitis, asthma, drug allergy, eczema, and urticar- in 2015, in 6 regions that included Erenhot, Xilinhot, Duolun, ia), smoking habit, cooking and heating mode, pets and live- Tongliao, Kailu, and Jarud regions. Study participants were en- stock, infant breastfeeding history, and dietary details were rolled to participate in the survey using random cluster sam- collected using the same questionnaire for all participants. pling. The local population distribution was considered and ad- Also, the height (barefoot) and body weight for all study par- justed before cluster sampling based on data obtained from ticipants were measured. Indexed in: [Current Contents/Clinical Medicine] [SCI Expanded] [ISI Alerting System] This work is licensed under Creative Common Attribution- [ISI Journals Master List] [Index Medicus/MEDLINE] [EMBASE/Excerpta Medica] NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) 1903 [Chemical Abstracts/CAS] Wang X.-Y. et al.: CLINICAL RESEARCH Prevalence of self-reported food allergy… © Med Sci Monit, 2018; 24: 1902-1911 Definition of the components of the self-reported food in the adult group but not the child group (P<0.001, P=0.335, allergy questionnaire respectively). As shown in Figure 2A, the self-reported preva- lence of food allergy decreased significantly with age P( <0.01). In this study, the presence of self-reported food allergy was The highest prevalence of self-reported food allergy was found defined by asking all participants whether they had experi- in the age group between 1 and 10 years, with a prevalence of enced a reaction to food during the past year, in the absence 40.0%, followed by the age group of between 11 and 20 years, of supporting confirmatory tests and clinical diagnosis. Multiple with a prevalence of 29.0%. The lowest self-reported preva- food allergies were defined as³ 3 self-reported food allergens. lence of food allergy was present in the >60 years old group (6.7%). The median (IQR) age of the participants with self-re- Ethnicity was determined from the study participant’s identi- ported food allergy was significantly lower than the participants ty (ID) card, as Mongolian or Han. The body mass index (BMI) without self-reported food allergy (P<0.001) (Table 1). Among was defined according to the World Health Organization 6 studied regions, the prevalence was highest in Xilinhot but (WHO) criteria, with a BMI <25 kg/m2 (lean or healthy); a BMI lowest in Jarud, which was in consistent with age distribution between 25–29 kg/m2 (overweight), and a BMI ³30 kg/m2 and family income (P<0.001). (obese). Education status was categorized as low (primary education only, or no education), medium (completion of sec- The Mongolian participants in this survey had a greater prev- ondary school or high school) and high (graduated from col- alence of food allergy when compared with Han participants lege or university).