Quest Diagnostics has conducted the largest study of allergies in US history, using the ImmunoCAP® specific immunoglobulin E (IgE) blood test (ImmunoCAP), the “gold standard” of allergy blood tests, which has provided fodder for many news stories in recent days. Here we present the executive summary:
• America’s allergy problem is increasing. Our analysis found that the overall allergen-sensitization rate increased by 5.8% over the 4-year study period. In addition, the number of patients tested for these 11 allergens increased 19%, significantly faster than growth in laboratory testing in general.
• Sensitization to 2 common environmental allergens is increasing, consistent with prior climate change research. Sensitization to common ragweed grew 15% – more than any other allergen we analyzed – with the Southwest, Mountain, and Plains States experiencing the highest sensitization rates. These findings are consistent with other research suggesting climate change may
contribute to an increase in certain environmental allergens, such as ragweed. Mold sensitization grew 12%, a finding that is potentially clinically important given other research showing that molds may trigger allergic sensitization and aggravate asthma.
• Allergies are prevalent throughout the u.S., occurring in each of the country’s 30 largest cities. Yet, some cities demonstrated higher rates of sensitization than others, with Dallas, Phoenix, Baltimore, Washington, D.C., and Boston experiencing the greatest burden.
• Men had higher sensitization rates than women at all ages, a novel and potentially clinically significant finding. This novel finding differs from other studies that suggest that allergies are more prevalent among women. While additional research is required, we hypothesize that the criteria for positive specific-IgE allergic response may differ between males and females, a finding of potential clinical significance. We provide 3 hypotheses for why our research differs from prior studies, including the possibility that the criteria for positive
specific-IgE allergic response may differ between males and females, and possibly at different ages.
• Children had higher sensitization rates than adults. Of children tested between 2 and 17 years of age, 53% showed sensitization to 1 or more allergens. Nearly 1 in 5 children with sensitization showed a high degree of IgE sensitization, compared to about 1 in 10 adults (see page 21).
• Allergies progress along a pattern known as the allergy march. The allergy march is a well-documented phenomenon by which sensitization to foods early in life may heighten a child’s likelihood of developing more severe allergic disease, including asthma, later in life. Our cross-sectional study is the largest to reveal a pattern of allergen sensitization consistent with the allergy march, with high rates of food-allergen sensitization most commonly found in early
childhood and high rates of sensitization to other allergens occurring more frequently with age. To better control the allergy march, physicians may periodically evaluate patients with allergies to assess changes in allergen sensitization.
• Peanut sensitization was high in children. Peanuts were the most common source of food sensitization in children 6 to 18 years of age, affecting nearly 1 in 4 school-aged children tested. Yet, peanut sensitization is even more prevalent in children 5 years of age and younger, affecting about 30% of children in this age group. Our data suggest peanut allergies remain an important source of concern in children.
• Patients with asthma had more allergies. On average, patients with asthma who were also found to have IgE sensitization were sensitive to 4.1 allergens compared to 3.4 allergens in patients who were not identified as having asthma. The link with asthma was strongest for indoor allergens such as mold, cats and dogs, and house dust mites. Our findings support medical guidelines recommending that clinicians and patients with asthma identify and minimize exposure to allergens that may aggravate asthma.
• Economically disadvantaged children were 18% less likely to be tested by the age of 5 than economically advantaged children. This novel finding suggests that economically disadvantaged children may be less likely to have their allergies diagnosed in early disease stages, when treatment may help prevent the onset of the allergy march leading to more severe allergy-related conditions, including asthma.
• The widespread availability of blood-based allergy testing is changing clinical practice. Allergies are increasingly being diagnosed by pediatricians and other primary care physicians, whose ordering of ImmunoCAP from Quest Diagnostics grew 46% and 49%, respectively, over the 4-year period. Ordering from allergists, in contrast, grew by only 23% over the same time period. The states of New York and New Jersey, as well as the Pacific Northwest, led the
country in the adoption of blood-based allergy testing, while the mid-Atlantic, Great Lakes, and Midwestern regions lagged behind.
For the full report, click here.