Natural History of Conditions That Co-Exist With Food Allergy
Food Allergy (FA) may coexist with asthma, atopic dermatitis (AD), eosinophilic esophagitis (EoE) and exercise-induced anaphylaxis. The presence of FA can be a predictor of acute, severe asthma. Moreover, the food may be a trigger for exercise-induced anaphylaxis. An elimination of food allergens in sensitized individuals can improve the symptoms of some concomitant co-morbid conditions.
1. ASTHMA
Four U.S. studies assessed the relationship of food allergies to asthma. In addition, two studies dealing with the fatal or near fatal anaphylaxis to foods in U.S. Children reported that all or almost all patients who died also had asthma.
Furthermore, as already noted in numerous studies, concomitant asthma is highly prevalent among the patients diagnosed with FA. These studies also drew several additional conclusions.
● Food-allergic asthmatics were more likely than the non-food allergic asthma patients to have had a hospitalization for asthma and had increased emergency department visits for asthma.
● Sensitized (e.g., to milk, wheat, peanut, or egg) asthmatic children had a higher rate of hospitalization than non-sensitized asthmatic children and also required more steroid use.
● The presence of self-reported FA was significantly more likely in patients admitted to the ICU compared to ambulatory care asthma patients or those admitted to the hospital, but not to the ICU.
● The presence of FA is a risk factor for asthma severity. Moreover, the presence of asthma may substantially increase the risk of death from anaphylaxis to food proteins.
ATOPIC DERMATITIS
In summary:
AD and FA are highly associated. When a FA is outgrown, the re-introduction of the food in the diet will not result in recurrence or worsening of the AD.
As noted previously, up to 37 percent of children under 5 years of age with moderate-to-severe AD will have IgE-mediated FA. Whether FA can exacerbate AD is still controversial in part because the signs and symptoms of food allergen exposure are so pleomorphic and because well-designed relevant food allergen avoidance trials have rarely been done in AD subjects.
A systematic review of nine randomized controlled trials, which assessed the effects of dietary exclusions for the treatment of established AD in unselected subjects, found little evidence to support the role for food avoidance.
However, several studies found an improvement in pruritus when the egg-allergic AD subjects were placed on an egg-free diet.
In a U.S. study of the natural history of FA in children with AD, the children with a mean age of 8 months (range 3 to18 months) were diagnosed using a DBPCFC.
It showed,
● 60 percent were allergic to a single food.
● 28 percent were allergic to two foods.
● 8 percent were allergic to three foods.
● 4 percent were allergic to four foods.
● Milk, peanut and egg were the most likely to produce positive food challenges
After their initial diagnosis, all children were placed on allergen-restricted diets, with a history of compliance of 90 percent. After one or two years, the patients underwent repeat food challenge tests.
● 26 percent of patients lost all evidence of symptomatic FA.
● Overall, 31 percent of the 1,221 food allergies were outgrown after one year of
food avoidance.
● All patients who outgrew their re-activity to a specific food had the food reintroduced into their diets with no recurrence of symptoms and no worsening of AD at a follow-up from six months to four years.
The patients who developed both skin and respiratory tract symptoms at the initial food challenge were much less likely to outgrow their FA than patients whose initial symptoms were limited to skin only or skin and gastrointestinal tract symptoms.
EOSINOPHILIC ESOPHAGITIS
In summary:
Eosinophilic esophagitis (EoE) is commonly associated with sensitization to foods. The natural history of EoE is that of a chronic relapsing condition. There is insufficient data to judge the impact of food sensitization on the natural history of EoE and vice versa. There are data to support the beneficial effect of food elimination diets on the clinical course of EoE in patients who also have FA.
Three U.S. studies examined the natural history of EoE in children. Most children were diagnosed within the first three years of life with symptoms including emesis, abdominal pain, heartburn, dysphagia, airway symptoms, cough and chest.
● In one study, the symptoms were grouped into age-related categories as “refusal to eat”in toddlers, gastroesophageal reflux or vomiting in young school-age children, and dysphasia and food impaction in older children.
● In two studies with adequate follow-up, most patients remained symptomatic and resolution was uncommon. (14 percent 37 and 2 percent 39 ). However, progression of eosinophilia to other parts of the gastrointestinal tract was very different. (77 percent 37 and 0 percent 39 ).
EXERCISE-INDUCED ANAPHYLAXIS
In summary:
Exercise-induced anaphylaxis in adults is triggered by foods in about a third of patients and has a natural history marked by frequent recurrence of the episodes.
A U.S. study of the natural history of exercise-induced anaphylaxis comes from a survey of 279 patients aged 18 or older identified at a single center from 1980 until 1993.
Thirty seven percent of patients reported a food trigger, most commonly crustacean shellfish (16 percent), alcohol (11 percent), tomatoes (8 percent), cheese (8 percent), and celery (7 percent).
● All patients met criteria for exercise-induced anaphylaxis (anaphylactic symptoms, urticaria, and/or angioedema with symptoms consistent with upper respiratory obstruction) or had cardiovascular collapse during exercise.
● 75 percent of the patients were female.
● The mean age was 37 years with an onset of symptoms at age 26, and the mean duration of symptoms was 10.6 years.
● The average number of episodes per year at the time of initial presentation was 14.5, but this frequency decreased to 8.3 at the time of the survey.
● Approximately 33 percent of patients had no attacks in the 12 months prior to the survey.
● The most frequently occurring symptoms were pruritus (92 percent), urticaria (86 percent), angioedema (72 percent), flushing (70 percent) and shortness of breath (51 percent).
● About 50 percent of the patients reported seasonal rhinitis or dust allergies, 19 percent also reported having asthma and 10 percent had eczema.
Although this study suggests a role for FA in the pathophysiology of exercise-induced anaphylaxis, the results must be interpreted cautiously since the diagnosis of FA was not based on an objective testing.
ALLERGIC RHINITIS
IgE-mediated FA does not commonly manifest as rhinitis. Similarly, allergic rhinitis is not thought to be a risk factor for the development of FA.
