Association Between Atopic Disease and Anemia in US Children
Drury KE, Schaeffer M, Silverberg JI
JAMA Pediatr. 2015 Nov 30. [Epub ahead of print]
Atopy and Anemia in Children
Atopy is a constellation of four inflammatory diseases—asthma, atopic dermatitis (eczema), allergic rhinoconjunctivitis (hay fever), and food allergies—with atopic patients typically presenting with one or more of these conditions in early childhood. Prevalence estimates vary, but data from a recent (1997-2013) US National Health Interview Survey (NHIS) that included 207,007 children and adolescents showed prevalence rates of 17.1% for hay fever, 12.8% for asthma, 9.5% for eczema, and 4.2% for food allergies.
Chronic inflammation is the hallmark of atopic diseases. Whereas atopic dermatitis and asthma manifest with inflammation of a specific organ system (skin and lungs, respectively), all atopic individuals share such markers of systemic inflammation as elevated serum immunoglobulin E levels and eosinophilia. Furthermore, atopy in adults—such as psoriasis—is associated with comorbid conditions, including obesity, hypertension, and cardiovascular disease. Atopic children are at increased risk for infection,[2,3] may be exposed to immunosuppressive medications, or may be on restrictive diets—all of which are risk factors for anemia.
In this context, Drury and colleagues used two large population-based surveys to determine whether atopic children and adolescents are more likely to have childhood anemia than their nonatopic peers. They mined relevant data from two large, cross-sectional population-based studies in the United States: (1) the NHIS, 1997-2013, a caregiver- and self-reported survey of 207,007 children and adolescents, and (2) the National Health and Nutrition Examination Survey (NHANES) (August 1, 2014, to August 28, 2015), which included both caregiver-reported information and laboratory data from 30,673 children and adolescents.
After controlling for age, sex, race/ethnicity, household education level, income, household size, and birthplace, investigators found the following:
Children with any form of atopy had higher odds of being diagnosed with anemia than their nonatopic matched peers;
On the basis of the NHIS data, children with food allergies had the highest prevalence of anemia (odds ratio [OR], 2.08), followed by children with eczema (OR, 1.83), hay fever (OR, 1.57), and asthma (OR, 1.31); and
Using the NHANES data, children with eczema or asthma were more likely to have anemia (OR, 1.93 and 1.33, respectively), particularly microcytic anemia (OR, 2.03 and 1.61, respectively). In contrast to the NHIS data, a history of hay fever was not associated with anemia in the NHANES study (OR, 0.85).
This meta-analysis of two large US-population–based pediatric surveys shows a compelling statistical link between childhood atopy and anemia. Breaking down this association further, eczema and asthma showed the most consistent association with microcytic anemia.
As Drury and colleagues note, atopic children may be at greater risk of developing anemia as a result of multiple factors, including dietary restrictions, failure to thrive, anemia of chronic disease, and medication-induced anemia. Further studies are needed to sort out which of these factors are most responsible for the observed association.
Does the severity of eczema or asthma correlate with the likelihood and severity of anemia? Owing to study limitations, they could not tease this information from the available survey data. Using limited laboratory data from the NHANES study, they determined that the anemia associated with asthma and eczema is primarily microcytic, but they couldn't characterize it further (eg, anemia of chronic disease, iron-deficiency anemia). Future studies should therefore include disease severity data, a detailed history of systemic medications that may contribute to anemia, nutritional data, and a more detailed laboratory profile for cases of anemia, including markers of iron storage (serum iron, ferritin, and total iron-binding capacity).
For now, one take-home message seems clear: Children with eczema and other atopic diseases should be checked routinely for clinical and laboratory evidence of anemia.
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Cite this: Is the Atopy/Anemia Link in Children Real? - Medscape - Dec 24, 2015.