Better research needed to diagnose, manage food allergies

Although food allergies affect between 1% and 10% of the population, guidelines for the treatment and management of these conditions are lacking, according to a recently published review.

Researchers from VA Palo Alto Healthcare System in California reviewed 12,378 titles in electronic databases for evidence on the prevalence, diagnosis, management and prevention of food allergies. There were 72 studies on allergies to cow’s milk, hen’s egg, peanut, tree nut, fish and shellfish included in the analysis.

Fifty-one studies offered population-based estimates on the prevalence of food allergies, but method of diagnosis was not consistent, ranging from self-report to skin prick testing. Prevalence estimates, especially those based on self-report, lack precision, and universally accepted criteria for diagnosing food allergies are needed, according to the researchers.

Most studies examined the efficacy of commonly used approaches, including skin prick testing, serum food-specific immunoglobulin E (IgE) determinations and atopy patch testing. Though placebo-controlled food challenge is generally considered the criterion standard, limitations related to expenses, specialized personnel time, risk of anaphylaxis and lack of criteria for identifying a positive result inhibits widespread use of this method.

No statistically significant differences between skin prick testing and serum food-specific IgE existed when compared with food challenge, according to the results. Insufficient data precluded similar evaluation for atopy patch testing for peanut, tree nut, fish or shellfish allergies. Combining tests to improve accuracy failed to reach conclusive results.

Evaluations of management strategies also were insufficient, according to the researchers. Elimination diets were only examined in one study due to concerns about testing this approach in individuals with life-threatening food allergies. Little evidence exists for less serious allergic reactions, including atopic dermatitis and eosinophilic esophagitis.

Studies on immunotherapy indicated possible efficacy as a treatment of food allergy, although evidence on long-term effects is missing. The safety of immunotherapy likely depends on the type of food and method of administration, but such safety evidence is scarce.

Several studies evaluated food substitution as a management strategy. Results showed that the use of hydrolyzed formula instead of cow’s milk may inhibit the development of the allergy in high-risk infants. “High risk” and “hydrolyzed formula,” however, have no standard definitions.

Several studies yielded positive results for the use of probiotics with breast-feeding and hypoallergenic formula as a food allergy prevention strategy, but data do not exist on their independent effects.

Chafen JJS. JAMA. 2010; 303:1848-1856.

Follow the PediatricSuperSite.com on Twitter.