Published Online: July 2013
Food allergy affects approximately 5% of US children and the prevalence is rising. One lingering question is if certain population groups are at more or less risk of developing food allergy, and if so, if this is because of a disparity – i.e., a gap in the access to (or quality of) health care across race, ethnicity and socioeconomic status. Limited data are available within food allergy pertaining to health disparities. However, exploration of such disparities may help us understand if certain groups are more or less likely to develop food allergy, more or less likely to receive adequate healthcare related to food allergy, or if the burden of living with food allergy is more difficult for some groups than others. Race is a particularly important disparity to identify, given that racial disparities are present for other allergic disorders, such as asthma and atopic dermatitis, and are well known to exist in other major health conditions such as heart disease, hypertension, and diabetes. Moreover, recent observational data have suggested that black children may be more susceptible to food allergy. This month, new research highlighted in The Journal of Allergy and Clinical Immunology: In Practice, by Greenhawt et al, presents results of a systematic review of the literature to determine if there is an association between black race and food allergy in US children, and if so, to what extent race changes one’s risk of having food allergy.
A team of investigators from the University of Michigan, the Centers for Disease Control and Prevention, the former Food Allergy & Anaphylaxis Network (now Food Allergy Research and Education), and the Massachusetts General Hospital conducted a systematic review to evaluate evidence related to this issue. (A systematic review is a highly organized approach to identify and evaluate all known medical literature pertaining to a particular study question.) The team reviewed 645 literature citations, but after elimination of non-US literature, review articles, abstracts, and citations that did not discuss racial disparities, only 20 met selection criteria for further evaluation. The team identified 4 working definitions of “food allergy” among these 20 citations: 1) food allergy determined by clinic-based diagnosis (history of reaction in combination with sensitization data and/or challenge); 2) serologic evidence of sensitization but no accompanying history of clinical reactivity; 3) caregiver-reported food allergy without accompanying evidence of physician diagnosis or sensitization; and 4) indicators of food allergy healthcare utilization, such as ICD-9 codes, without firm confirmation of actual reactivity.
The Team noted that 14 of the 20 studies indicated some degree of association between black race and food allergy in US children. However, these studies all had significant limitations. Six studies indicated either higher odds or higher reported rates of food sensitization in black children compared to white children, but no further assessment was made to determine if ingestion of the sensitized food led to clinical reactivity (i.e., an allergic reaction). Four studies noted higher proportion or odds of caregiver reported food allergy in black children compared to white children but were unable to provide more data to establish if these individuals were sensitized to any food, had a physician diagnosis of food allergy, or if ingestion of the reported food led to clinical reactivity. Two studies identified disparities in health care utilization: one suggested a higher odds of emergency room visits for anaphylaxis to food in black children compared to white children; the other suggested lower odds of parents of black children being able to properly identify the symptoms of food allergy or food allergy triggers. However, both of these studies were limited as there was no known assessment as to whether ingestion of the food in these individuals led to actual symptoms. Finally, two studies suggested that black race was associated with lower odds of developing food sensitization or caregiver-reported food allergy, but had similar limitations of not being able to verify if ingestion of the foods in question led to actual symptoms.
Because the studies were so distinctly different in study design, including definition of food allergy, a quantitative meta-analysis was not possible, and the authors concluded that there is insufficient evidence, to date, to support the idea that black children are disproportionately affected by food allergy. The authors raised concerns about the inconsistency in how food allergy was defined, and the use of indirect measures that did not directly assess if ingestion of the food actually caused symptoms to develop. These are well-known limitations of using data that rely entirely on caregiver-reports, positive blood tests, and discharge codes. While these may be the most cost-effective ways of estimating food allergy prevalence across a large population, they fall short of providing a strong answer as to whether black race makes a person more susceptible to having food allergy; more rigorous research is required. However, the authors did note that 14 studies suggested a possible association. The researchers remain hopeful that future research will address the highlighted limitations and provide a clear answer if black race places someone at higher risk of developing food allergy.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.