Allergies Are on the Rise; Focus on Prevention


The prevalence of atopic dermatitis increased fourfold in the past 50 years.

Allergy, the sixth-leading cause of chronic disease in the United States, is on the rise. Up to 30% of some populations, particularly in developed European countries and in the United States, suffer from some form of allergic disease, according to Benjamin Gold, MD, associates professor of pediatrics at Emory University School of Medicine in Atlanta.

Gold and José Saavedra, MD, associate professor of pediatric gastroenterology and nutrition at Johns Hopkins University School of Medicine in Baltimore, recently spoke during a media briefing, sponsored by the Nestle Nutrition Institute.

Infants and children are particularly prone to allergy, and this condition occurs in 8% of children 6 years of age and younger. Food allergies are the most common in children, and 90% of those allergies can be attributed to five foods: cow's milk, soy, wheat, peanuts and tree nuts and eggs.

Children most commonly experience food allergies in the form of gastrointestinal, respiratory or skin manifestations. Eosinophilic gastroenteritis, in which inflammatory cells infiltrate the gastrointestinal tract in response to a trigger, is clearly on the rise, according to Gold, who is also the director of the division of pediatric gastroenterology and nutrition at Emory healthcare and Children's Healthcare in Atlanta. The most common allergic manifestation in infants is atopic dermatitis.

Atopic dermatitis trends, significance

The prevalence of atopic dermatitis increased fourfold in the past 50 years, Gold said. In 1946, 5% of the population suffered from atopic dermatitis. By 1994, prevalence had risen to 20% of the population. Today, about 15 million Americans suffer from atopic dermatitis. There is a 17% prevalence of this condition in children by 6 months of age. Up to 60% of children with severe atopic dermatitis also have food hypersensitivity.

Atopic dermatitis can affect infants' quality of life, according to Gold. It can lead to itchiness, irritability, altered sleep, pain/colic (when associated with a gastrointestinal allergy), stress associated with treatment, and disruption of family interactions.

Quality of life in older children is also affected. Children may also experience stress related to treatments and sleep deprivation due to nighttime scratching. Irritability and sleep disruption associated with pruritis takes a significant toll on both infants and parents. Atopic dermatitis also affects social interactions, personal relationships and school in older children. According to Gold, self-esteem issues may develop, particularly if alopecia develops.

"When a child is old enough to have an understanding of their own body image, it can result in fairly profound negative self-esteem and affect self-consciousness," Gold said.

Atopic dermatitis places a heavy burden on health care. Of people covered under a private insurer, 2.4% have atopic dermatitis, as do 2.6% of people covered under Medicaid. A conservative estimate of the costs rising from atopic dermatitis is $1.6 billion, although according to Gold, the all-inclusive costs are about $3.8 billion, because most studies do not consider indirect costs, such as parents leaving work to take care of children.

Atopy to asthma

According to Gold, atopic dermatitis may be the first step in what has been called the "allergic march," or allergic manifestations that continue to present throughout life. Approximately 75% to 80% of people with atopic dermatitis develop allergic rhinitis, and more than 50% develop asthma.

Gold describes the allergic march as beginning with atopic gastrointestinal and dermal allergy. Many times, the allergy sufferer then experiences upper respiratory tract problems: rhinitis and rhinoconjunctivititis. According to Gold, some cases of otitis media may be stimulated by allergy. Lower respiratory problems, such as wheezing then develop, and finally the patient may be diagnosed with allergic asthma. Increasingly, a relationship between the development of atopy in early infancy is being associated with development of asthma later in life, according to Gold.

Preventing allergy

According to Saavedra, medical and scientific vice president for the Nestlé Nutrition Institute, allergy can be dealt with through tertiary, secondary or primary prevention. Tertiary prevention deals with treatment to avoid recurring symptoms, while secondary prevention finds the offender through skin or blood tests and works to avoid disease expression. Primary prevention, on the other hand, is the actual prevention of sensitization.

Saavedra cited pediatric allergy as a major health issue. The incidence and prevalence in developed countries, the high costs of treatment, the impact on the quality of life and the magnification of the problem due to the allergic march mean that primary prevention should be a priority. The allergic march from atopic dermatitis to asthma magnifies the problem, potentially extending allergy well beyond infancy or childhood, according to Saavedra.

While tertiary prevention is the most common way of dealing with allergic disease, according to Saavedra, more emphasis needs to be placed upon primary prevention.

"It certainly behooves us to continue doing the best we can to see if we can avoid the problem in the first place," said Saavedra.

For the general population, breast-feeding is unquestionably the best way to prevent chronic disease, including allergy, Saavedra said. Delayed exposure to solid foods for 4 to 6 months may also decrease or delay onset of allergic manifestations, although the evidence is inconclusive.

Traditional strategies

The AAP recommends traditional nutrition strategies for decreasing the risk in high-risk infants, which Saavedra defined as infants whose parents or siblings have a history of allergies. The past or present history of atopic dermatitis, allergic rhinitis, urticaria or asthma in a parent or sibling increases an infant's risk of developing allergy. In high-risk, breast-feeding infants, the current evidence does not support a major role of maternal dietary restrictions. "Other traditional strategies include avoiding allergens in solid foods during weaning, and use of extensively hydrolyzed formulas for infants who do not have the benefit of breast-feeding," said Saavedra. There is modest evidence that the onset of atopic disease may be delayed or prevented by the use of hydrolyzed formulas compared with formula made with intact cow milk protein, particularly for atopic dermatitis. 

These strategies may be effective for at-risk infants, but are not practical for most infants since dietary restrictions are difficult, the cost of extensively hydrolyzed formulas is high and they don't taste good. In addition, there is no good way to identify most infants at risk who may benefit from primary prevention.

A positive family history is a common marker of increased risk, but there are no adequately standardized public health tools to assess family history, and more than one half of the infants who develop atopic disease do not have a positive family history of allergies.

Saavedra recommended the development of better predicting tools and the implementation of public health measures to identify infants at risk – particularly, better methods to identify infants at risk who do not have a family history of allergy.

"Impact on cost, quality of life and the frequency with which this problem is happening does urge us to adopt better alternatives for primary prevention, particularly to those food allergies that are extremely common in infancy and may go on to become a problem that persists for the rest of that infant's life," Saavedra said.

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