Severity and threshold of peanut reactivity during hospital-based open oral food challenges: An international multicenter survey.

BACKGROUND: Peanut allergy is classically managed by food avoidance. Immunotherapy programs are available at some academic centers for selected patients reacting to small amounts of peanut during food challenge. We aimed to determine and compare reaction thresholds and prevalence of anaphylaxis during peanut oral challenges at multiple specialist allergy centers. METHODS: A retrospective, international survey of anonymized case records from seven specialist pediatric allergy centers from the UK and Ireland, as well as the Australian HealthNuts study. Demographic information, allergy test results, reaction severity and threshold during open oral peanut challenges were collated and analyzed. RESULTS: Of the 1634 children aged 1-18 years old included, 525 (32%) failed their peanut challenge. Twenty-eight percent reacted to 25 mg, while 38% only reacted after consuming 1 g or more of whole peanut. Anaphylaxis (55 [11%]) was 3 times more common in teenagers than younger children and the likelihood increased at all ages as children consuming more peanut at the challenge. Children who developed anaphylaxis to 25-200 mg of whole peanut were significantly older. Previous history of reaction did not predict reaction threshold or severity. CONCLUSIONS: More than a third of the children in this large international cohort tolerated the equivalent of one peanut in an oral challenge. Anaphylaxis, particularly to small amounts of peanut, was more common in older children. Tailored immunotherapy programs might be considered not only for children with low, but also higher reaction thresholds. Whether these programs could prevent heightened sensitivity and anaphylaxis to peanut with age also deserves further study.

Antihistamine use in children.

This review provides an overview of the use of antihistamines in children. We discuss types of histamine receptors and their mechanism of action, absorption, onset and duration of action of first-generation and second-generation H(1)-antihistamines, as well as elimination of H(1)-antihistamines which has important implications for dosing in children. The rationale for the use of H(1)-antihistamines is explored for the relief of histamine-mediated symptoms in a variety of allergic conditions including: non-anaphylactic allergic reactions, atopic eczema (AE), allergic rhinitis (AR) and conjunctivitis, chronic spontaneous urticaria (CSU) and whether they have a role in the management of intermittent and chronic cough, anaphylaxis, food protein-induced gastrointestinal allergy and asthma prevention. Second-generation H(1)-antihistamines are preferable to first-generation H(1)-antihistamines in the management of non-anaphylactic allergic reactions, AR, AE and CSU due to: their better safety profile, including minimal cognitive and antimuscarinic side effects and a longer duration of action. We offer some guidance as to the choices of H(1)-antihistamines available currently and their use in specific clinical settings. H(1)-antihistamine class, availability, licensing, age and dosing administration, recommended indications in allergic conditions and modalities of delivery for the 12 more commonly used H(1)-antihistamines in children are also tabulated.

Optimising treatment of allergic rhinitis in children.

Acute and chronic symptoms of allergic rhinitis (AR) can disrupt school and leisure activities, significantly reducing quality of life. Symptoms often impair sleep, resulting in tiredness and poor concentration. Children with seasonal AR perform significantly worse in summer exams, relative to their mock exam results, when compared with their peers. Those individuals showing most symptoms are also likely to be affected by other allergic diseases, magnifying the detrimental impact on quality of life. Nasal blockage is the most common complaint associated with chronic AR, with acute exacerbations causing sneezing, clear nasal discharge and itchy eyes following exposure to the relevant airborne triggers. Allergen avoidance measures should be instituted according to seasonal or perennial symptomatology guided by allergy testing, alongside nonsedating antihistamines such as cetirizine or loratadine. Continued symptoms should be treated with regular intranasal steroid spray. Anti-leukotrienes should be considered early in children presenting with multi-trigger wheeze. Temporal patterns of exacerbation give clues as to the most important aeroallergens implicated. In the UK, tree pollen allergy predominates throughout the spring, whereas those affected by grass pollen allergy may find their symptoms increasing over the summer months. Perennial AR symptoms are the result of exposure to house dust mites, animals and moulds. Children who are allergic to these often find the winter more troublesome as they spend more time indoors and the central heating disperses these household allergens. Where continuing deterioration presents a challenge and allergic symptoms remain uncontrolled, patients should be referred to a specialist allergy service to be considered for immunotherapy.

Diagnosing and managing food allergy in children.

The prevalence of food allergy in children in the UK is now around 5%. The number of children put on restricted diets by their parents because of presumed allergy is likely to be much higher. Accurate diagnosis of food allergy is essential in order to ensure that the correct foods are carefully avoided while safe foods are not excluded unnecessarily. IgE-mediated (immediate type) reactions are the result of mast cell degranulation leading to histamine release. The typical signs of lip swelling, urticaria and possible progression to respiratory compromise (anaphylaxis) are usually clearly described, occurring within minutes of exposure to the food. Non IgE-mediated (delayed type) responses tend to start 2-6 hours, occasionally longer, after exposure and cause less specific signs/symptoms, less obviously allergic in origin. Where an immediate type allergic reaction is suspected on clinical history, allergy testing should be performed to confirm the diagnosis. This could involve either skin prick testing or specific IgE blood tests. Results must be interpreted in the context of the clinical history. The mainstay of management is allergen avoidance. The child and carers also need to know how to recognise and treat any future allergic reactions. There should be a written emergency plan in place. The plan should include advice to take a fast-acting antihistamine if any accidental exposure and reactions occur. Where there is a history of anaphylactic reaction or ongoing asthma, adrenaline auto-injectors should be prescribed as these are the major risk factors for future severe reactions. Non IgE-mediated food allergy is most common in early infancy. The diagnosis of non IgE-mediated food allergy relies on a two-stage process: strict exclusion of suspected allergen(s), only one at a time; re-challenge with suspected allergen(s), one at a time, to see if symptoms recur.

Recognition and management of food allergy in children.

Incidence of food allergy has been increasing and is more commonly seen in children. Allergic reactions can vary, with symptoms ranging from mild to severe. This article aims to explore the immunological mechanisms involved in food allergy, as well as distinguishing between immunoglobulin E (IgE) mediated and non-IgE-mediated reactions. Careful diagnosis of the allergic child is essential and the article describes validated tests carried out in this process. Adopting a multidisciplinary approach to the management of children with allergies is vital because it ensures patients and carers are supported, empowered and therefore able to enjoy an improved quality of life.

Identifying and managing Hymenoptera venom allergy.

Hymenoptera venom allergy is an immunoglobulin E (IgE)-mediated hypersensitivity to the venom of insects from the Hymenoptera order and is a common cause of anaphylaxis. A diagnosis of venom allergy is made by taking an accurate medical, family and social history, alongside specific allergy testing. Systemic reactions to Hymenoptera venom occur in a small proportion of the population; these range from mild to life-threatening in severity. Treatment for local reactions involves the use of cold packs, antihistamines, analgesia and topical corticosteroids to help alleviate swelling, pain and pruritus. Venom immunotherapy is the treatment of choice for reducing the incidence of future anaphylactic reactions in individuals who have signs of respiratory obstruction or hypotension. Venom immunotherapy is the most effective treatment in reduction of life-threatening reactions to venom, and can improve quality of life for individuals. Treatment should only be provided by experienced staff who are able to provide emergency care for anaphylaxis and life-threatening episodes. A risk assessment to deliver treatment should be undertaken before treatment is commenced.