Inconsistency of diagnosis may explain it.
On the professional front, these allergies are often being diagnosed by a variety of nonallergists, such as general practitioners and emergency department physicians; hence, the diagnoses may not be accurate.
In fact, because different types of professionals having different perspectives deal with this condition, we have peephole views instead of a full picture.
On the public front, patient organizations have markedly increased awareness about food allergy, for better or worse.
In addition, some patients never seek a formal diagnosis for what they perceive to be a food allergy, yet research often relies on self-reports.
Studies to date do not give us enough reliable data to conclude that there is a food allergy epidemic. They have been limited by three main issues.
First is the issue of case definition: What are we trying to measure? The general definition of food allergy is an adverse reaction to food on an immunological basis, either IgE or non-IgE mediated.
But we need a more rigorous, operational definition that establishes an undebatable correlation between the food and the subsequent reaction, using a food challenge and consideration of the condition's natural history.
Studies have varied widely in respect to which food triggers, signs and symptoms, diagnostic criteria, and timing of food reactions they have used to determine the presence of food allergies.
Second is the issue of methodology: How do we go about measuring the prevalence? A variety of populations, durations of assessment, and designs (such as prospective vs. retrospective) have been used.
Third is the issue of the source of data: Is it primary or secondary? Some studies have used secondary sources, which are not specifically designed to collect data on food allergy, for example, hospital admission data or primary care records. These data can be highly biased if not properly reviewed.
By way of example, a Danish study that used strict criteria for food allergy and assessed prevalence among unselected children in the general population found no increase between 1999 (2.2%) and 2005 (2.3%) (Pediatr. Allergy Immunol. 2005;16:567-73). Meanwhile, a meta-analysis found that the global prevalence more than doubled, from 2% to 5%, when self-reports were used (J. Allergy Clin. Immunol. 2007;120:638-46).
My conclusion is that we don't know at this time if a food allergy epidemic is occurring.
BY MARIA ANTONELLA MURARO, M.D., PH.D.
Dr. MURARO is director of the Veneto Region Referral Center for food allergy in the department of pediatrics at Padua (Italy) General Hospital. Dr. Muraro disclosed that she serves on the scientific advisory board of ALK, an international pharmaceutical company specializing in allergy products.
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|Title Annotation:||Is there a food allergy epidemic?|
|Author:||Muraro, Maria Antonella|
|Publication:||Internal Medicine News|
|Date:||Mar 15, 2009|
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