Biomedical subjects
Publications and source records attributed to G Lack.
We describe a case report of peanut and hens egg-dependent exercise-induced anaphylaxis in a 13-yr-old child, and assess the fundamental importance of careful investigations to differentiate food-dependent exercise-induced anaphylaxis from other forms of allergic reactions.
BACKGROUND: Latex allergy has been highlighted as a problem in children during the last decade based on a number of case series of children with particular problems such as spina bifida. The actual prevalence of latex allergy in the general United Kingdom population is unclear. OBJECTIVE: To estimate the prevalence of childhood latex allergy in the general population. METHODS: The Avon Longitudinal Study of Parents and Children is a geographically based cohort that has been prospectively followed since birth. The children were invited for skin prick testing at 7 years of age. RESULTS: Four subjects out of 1877 tested were sensitized to latex. None had a history of clinical reactions to latex. CONCLUSION: This study suggests that the prevalence of latex sensitization and clinical latex allergy in the general childhood population are very low, 0.2% (95% confidence interval 0.1-0.6%) and 0.0% (0-0.2%), respectively.
BACKGROUND: Allergic reactions to food are well recognized in both children and adults, but because of their relative infrequency their typical features may not be readily recognized by patients and their medical care givers who are not allergists. OBJECTIVE: We sought to investigate the circumstances and clinical characteristics of food allergies in adults and children in the community. METHODS: Self-completed questionnaire responses over a 6-month period from 109 members of the Anaphylaxis Campaign, the major British patient resource group for people who have suffered severe allergic reactions. RESULTS: One hundred and nine respondents reported 126 reactions during the study period. Seventy-five were children (under 16 years, median age 6 years at the time of reaction). Predictably more boys than girls were reported to have had reactions but more women reported reactions than men (P<0.05). Although the groups were equally aware of their food allergies the children had undergone diagnostic tests more often (P<0.001). Foods were implicated in 112 (89%) of reports. Restaurants were implicated less often (14%) than in other series, probably reflecting British eating habits. Children with asthma reported more severe reactions than those without asthma (P=0.008), although frequency or severity of recent asthma symptoms was not associated with severity of allergic reaction reported. When available, self-injectable adrenaline was used in 35% of severe reactions and 13% of non-severe reactions (P=0.01). A quarter of adults who received one dose of adrenaline also received a second dose. CONCLUSION: The allergens implicated in this report reflect previous data from similar patient groups in North America. Asthmatic children suffer more severe reactions than non-asthmatic children. It appears that British adults need better access to expert care of their allergies. Even when it is prescribed and available self-injectable adrenaline appears under-used in severe reactions. The incidence of severe but non-fatal allergic reactions in the UK may have been underestimated in the past.
BACKGROUND: Previous studies measuring the prevalence of allergen sensitization have been relatively small and used small numbers of allergens. To effectively evaluate children with atopic disease, we need an accurate knowledge of which allergens are important. OBJECTIVE: To measure the prevalence of sensitization within a large unselected birth cohort, to examine the associations between sensitization to different allergens and determine whether atopy can be defined by a small panel of allergens. METHODS: The Avon Longitudinal Study of Parents and Children is a population-based birth cohort of 13,638 singletons surviving to 4 weeks of age. The cohort was skin tested at 7 years of age to house dust mite (Dermatophagoides pteronyssinus), grass pollens, cat, peanuts, mixed tree nuts and egg and one of three other panels: animal danders, foods or aeroallergens. Sensitization was defined as a weal diameter of > or =3 mm. The strength of associations between sensitization to different allergens was tested by calculating the odds ratio adjusted for sensitization to D. pteronyssinus and grass pollen and gender. RESULTS: Valid data were obtained from 6412 singletons. Sensitization was most common to aeroallergens: grass pollens (8.5%), D. pteronyssinus (7.8%), cat (4.9%), D. farinae (3.6%), dog (2.7%), horse (1.4%), rabbit (1.4%). Of the foods tested, the most common sensitization was to peanut (1.4%) and mixed tree nuts (1.0%). More than 95% of subjects with sensitization to any of the 29 allergens tested were sensitized to one of grass, D. pteronyssinus or cat allergen. There were strong associations of multiple sensitizations both within and between different allergen classes (pollens, animals, foods, peanut and tree nuts). CONCLUSIONS: Seven-year-old children in the UK are primarily sensitized to aeroallergens, but also to peanuts and tree nuts. There are strong associations between sensitization within allergen groups as well as between allergen groups. Further studies are required to observe whether similar associations are seen with clinical allergy to these allergens.
BACKGROUND: Allergic disease has been shown to impair health-related quality of life (HRQL). The relationship between HRQL and either allergen exposure or allergic inflammation has not been previously assessed. OBJECTIVE: To assess the relationship between HRQL and both grass pollen exposure and airway inflammation using the Paediatric Allergic Disease Quality of Life Questionnaire (PADQLQ). This is a novel questionnaire previously developed to assess the multi-system aspects of allergic disease. METHODS: Eighty-four subjects, aged 6-17 years, with seasonal allergic rhinoconjunctivitis, asthma and/or cutaneous manifestations were assessed before and during the grass pollen season. They were assessed with the PADQLQ, a visual analogue scale (VAS) to assess quality of life, symptom diary and exhaled nitric oxide (FENO). RESULTS: HRQL, as measured by the PADQLQ, significantly correlated with the average pollen count in the previous week (regression coefficient 0.038, 95% confidence interval (CI) 0.027-0.049, P<0.001). The PADQLQ score was also found to be significantly associated with airway inflammation as measured by FENO (regression coefficient 0.410, 95% CI 0.175-0.646, P=0.001). Additionally, PADQLQ showed a high degree of correlation with symptom scores and quality of life as measured by a VAS, good within-subject reliability and a small minimal important difference (0.20, 95% CI -0.09 to 0.49 on a seven-point scale). CONCLUSION: HRQL is related to both allergen load and allergic inflammation and the PADQLQ has excellent cross-sectional and longitudinal validity with respect to quality of life and symptoms.
Asthma, wheeze, eczema, and, to a certain extent, rhinitis are very common conditions among children. The prevalence of allergic disease in the general population has increased alarmingly over the past 25 years, particularly in Western industrialised countries. However, it is important to remember that the symptoms often associated with allergy can have other aetiologies. Evidence suggests that in most circumstances, only 30-40% of chronic allergic-type symptoms are due to allergy. Accurate diagnosis of the presence of allergy is therefore an important issue, particularly given the interventions that such a diagnosis may initiate. In this review, we examine management options for allergy, provide the evidence as to what proportions of patients with common allergic-type symptoms are actually allergic, and list other causes of such symptoms. The importance of allergy testing and the options available are described, particularly with reference to the role of the non-allergist.
BACKGROUND: Studies have demonstrated that families of children with food allergy have significant deficiencies in their knowledge of how to avoid allergen exposure and how to manage allergic reactions. This study aims to assess the impact of a multidisciplinary paediatric allergy clinic consultation on parental knowledge of food allergy and to determine the rate of subsequent allergic reactions. METHODS: Sixty-two subjects (<17 years) referred with food allergy were prospectively enrolled. Parental knowledge was assessed by questionnaire and EpiPen trainer. Families saw a paediatric allergist, clinical nurse specialist and dietician. Knowledge was reassessed after 3 months and rate of allergic reactions after 1 year. RESULTS: After one visit to the paediatric allergy clinic, there was a significant improvement in parental knowledge of allergen avoidance (26.9%, P < 0.001), managing allergic reactions (185.4%, P < 0.0001) and EpiPen usage (83.3%, P < 0.001). Additionally, there was a significant reduction in allergic reactions (P < 0.001). Children with egg, milk or multiple food allergies were more likely to suffer subsequent reactions. CONCLUSIONS: A single visit to a multidisciplinary allergy clinic considerably improves families' abilities to manage allergic reactions to foods with an accompanying reduction in allergic reactions. Young children with egg, milk or multiple food allergies were at greatest risk of further reactions.
BACKGROUND: While the ingestion of small amounts of an offending food can elicit adverse reactions in individuals with IgE-mediated food allergies, little information is known regarding these threshold doses for specific allergenic foods. While low-dose challenge trials have been conducted on an appreciable number of allergic individuals, a variety of different clinical protocols were used making the estimation of the threshold dose very difficult. OBJECTIVE: A roundtable conference was convened to develop a consensus clinical protocol for low-dose challenge trials for the estimation of threshold doses for specific allergenic foods. METHODS: In May 2002, 20 clinical allergists and other interested parties were invited to participate in a roundtable conference to develop consensus of the key elements of a clinical protocol for low-dose challenge trials. RESULTS: A consensus protocol was developed. Patients with convincing histories of food allergies and supporting diagnostic evidence including past challenge trials or high CAP-RAST scores can be enrolled in low-dose challenge trials. Care must be taken with younger patients to assure that they have not outgrown their food allergy. An approach was developed for the medication status of patients entering such trials. Challenge materials must be standardized, for example, partially defatted peanut flour composed of equal amounts of the three major varieties of peanuts (Florunner, Virginia, Spanish). Challenge materials must be appropriately blinded with sensory evaluation used to confirm the adequacy of blinding. A double-blind, placebo-controlled design should be used for low-dose challenge trials. Low-dose challenge trials would begin at doses of 10 microg of the allergenic food and would continue with doses of 100 microg and 1 mg followed by specific higher doses up to 100 mg depending upon the expert judgement of the physician; even higher doses might be applied to assure that the patient is indeed reactive to the particular food. A 30-min time interval would be used between doses, and reactive doses would be expressed as both discrete and cumulative doses. The goal of each challenge would be to develop objective symptoms; trials should not be discontinued on the basis of subjective symptoms only. Statistically, a minimum of 29 patients would be enrolled in low-dose challenge trials for each allergenic food because 0 reactors out of 29 patients at a particular dose allow the conclusion that there is 95% certainty that 90% of allergic individuals will not react to that dose. CONCLUSION: A consensus protocol was developed. Using this protocol, it will be possible to estimate threshold doses for allergenic foods, the lowest amount that elicits mild, objective symptoms in highly sensitive individuals.
The case of a 14-month-old boy with vitamin D deficiency rickets as a result of unsupervised dietary manipulation in the context of cow's milk allergy is presented. Adequate supervision by a qualified dietician, coupled with appropriate supplementation, is essential if nutritional compromise is to be avoided in children with food allergy.
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BACKGROUND: Exhaled nitric oxide (NO) has been proposed as a marker of airway eosinophilic inflammation in asthma. There is currently a paucity of longitudinal data relating it to allergen exposure and asthma symptoms. METHODS: Forty four children (6-16 years) with seasonal allergic asthma were sequentially followed before and during the grass pollen season. Asthma symptoms, lung function, NO levels, and pollen counts were recorded. The relationship between exhaled NO and both the pollen levels and asthma control were assessed longitudinally, comparing a subject's measurements with their previous ones. RESULTS: The median exhaled NO concentration was significantly increased during the pollen season (6.2 v 9.2 parts per billion (ppb), p<0.002; median change 2.9 ppb, 95% confidence interval 1.5 to 5.4). Exhaled NO was best associated with the mean pollen count in the week before measurement. It was also significantly associated with asthma control. CONCLUSIONS: The results suggest that, within a longitudinal model, the exhaled NO concentration is related to preceding allergen exposure and asthma control. It may be clinically more useful to compare exhaled NO values with a subject's previous values than to compare them with a population based normal range.
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BACKGROUND: Allergic asthma is usually considered to be provoked by aeroallergens. However, we have recently recognized a group of children with food allergies who also develop asthma when exposed to the aerosolized form of the food. METHODS: Between 1997 and 1999 we prospectively identified children with an immunoglobulin (Ig)E-mediated food allergy who develop asthma on inhalational exposure to the relevant food allergen while it is being cooked. Subjects were exposed for 20 min to the aerosolized form of the allergen and the symptoms and the lung function were monitored. Aerosolization was achieved by cooking the food in a small room. Where possible challenges were double-blinded. RESULTS: We identified 12 children with an IgE-mediated food allergy who developed asthma on inhalational exposure to food. The implicated foods were fish, chickpea, milk, egg or buckwheat. Nine out of the 12 children consented to undergo a bronchial food challenge. Five challenges were positive with objective clinical features of asthma. Additionally, two children developed late-phase symptoms with a decrease in lung function. Positive reactions were seen with fish, chickpea and buckwheat. There were no reactions to the seven placebo challenges. CONCLUSIONS: We have presented a prospective series of children with food allergy who developed symptoms of asthma with exposure to aerosolized food allergens. Our data demonstrates that, as in the case of other aeroallergens, inhaled food allergens can produce both early- and late-phase asthmatic responses. This highlights the importance of considering foods as aeroallergens in children with coexistent food allergy and allergic asthma. For these children, dietary avoidance alone may not be sufficient and further environmental measures may be required to limit exposure to aerosolized food.
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Allergic rhinitis (AR) is rarely found in isolation and needs to be considered in the context of systemic allergic disease associated with numerous comorbid disorders, including asthma, chronic middle ear effusions, sinusitis, lymphoid hypertrophy with obstructive sleep apnea, disordered sleep, and consequent behavioral and educational effects. The coexistence of AR and asthma is complex. First, the diagnosis of asthma may be confounded by symptoms of cough caused by rhinitis and postnasal drip. This may lead to either inaccurate diagnosis of asthma or inappropriate assessment of asthma severity with over treatment of the patient. The term "cough variant rhinitis" is therefore proposed to describe rhinitis that manifests itself primarily as cough that results from postnasal drip. AR, however, also has a causal role in asthma; it appears both to be responsible for exacerbating asthma and to have a role in its pathogenesis. Postnasal drip with nasopharyngeal inflammation leads to a number of other conditions. Thus sinusitis is a frequent extension of rhinitis and is one of the most frequently missed diagnoses in children. Allergen exposure in the nasopharynx with release of histamine and other mediators can cause Eustachian tube obstruction possibly leading to middle ear effusions. Chronic allergic inflammation of the upper airway causes lymphoid hypertrophy with prominence of adenoidal and tonsillar tissue. This may be associated with poor appetite, poor growth, and obstructive sleep apnea. AR is therefore part of a spectrum of allergic disorders that can profoundly affect the well being and quality of life of a child. Prospective cohort studies are required to assess the disease burden caused by AR in childhood and to further assess the potential educational impairment that may result. Because AR is part of a systemic disease process, its management requires a coordinated approach rather than a fragmented, organ-based approach.