Oral food challenges: result of a 16-year experience at a major teaching hospital in Thailand

BACKGROUND: Prevalence of food allergy is increasing all over the world including in Asia. Diagnosis of food allergy in Asia is usually made after family complaints or by elimination and/or reintroduction foods. This could lead to an inaccurate diagnosis and to incorrect information on epidemiology of food allergy. We, herein, reported results of a 16-year experience (1996–2012) of oral food challenge (OFC) performed in pediatric patients at a major teaching hospital in Thailand. OBJECTIVE: The major objectives of this report are to review types of foods selected for oral challenges, frequency of positive/negative challenges to these foods and the clinical reactions during challenges among these children. METHODS: Medical records of 206 children underwent OFC between 1996 and 2012 for various indications at the Allergy clinic of Pediatric Department, Siriraj Hospital, Mahidol University (age range, 4 months to 17 years) were retrospectively reviewed. Data including clinical data, skin prick test results and specific IgE levels were analyzed with respect to challenge results (positive/negative). During the period of the study, 2 separate investigations on shrimp allergy and wheat allergy were conducted. RESULTS: Sixty of 206 children (29%) had positive OFC, whereas 84 out of 306 OFC (27.5%) were positive. The most common food giving positive challenges in this study was shrimp (40%). Among children less than 3 years of age, the most common food with positive challenge was wheat (70%) whereas among children 3 years of age or older, shellfish was the most common food (42%). Cutaneous reactions were the most common reactions observed. CONCLUSION: Only 1 of 3 of children underwent OFC in this study had positive challenges. Shrimp was the most common food causing challenge in this study especially among children older than 3 year of age. Wheat has become another leading food besides cow's milk and egg in causing positive OFC in younger children in Thailand.

The Utility of Serum Tryptase in the Diagnosis of Food-Induced Anaphylaxis

PURPOSE: This study investigates the utility of serum tryptase for the confirmation of shrimp-induced anaphylaxis. METHODS: Patients with a history of shrimp allergy and positive skin prick tests (SPT) to commercial shrimp extract were recruited for shrimp challenges. Serum total tryptase was obtained at baseline and 60 min (peak) after the onset of symptoms. RESULTS: Thirty-nine patients were challenged. There were 12 patients with anaphylaxis, 20 with mild reactions and 7 without symptoms (control group). Characteristic features and baseline tryptase were not different among the 3 groups. The peak tryptase levels were higher than the baseline in anaphylaxis and mild reaction groups (P11.4 microg/L with 17% sensitivity, 100% specificity, infinity positive LR and 0.83 negative LR. The best cut-off for delta-tryptase was > or =0.8 microg/L with 83% sensitivity, 93% specificity, 11.86 positive LR and 0.18 negative LR. The best cut-off for tryptase ratio was > or =1.5 with 92% sensitivity, 96% specificity, 23 positive LR and 0.08 negative LR. CONCLUSIONS: The peak tryptase level should be compared with the baseline value to confirm anaphylaxis. The tryptase ratio provide the best sensitivity, specificity, positive and negative LR than a single peak serum tryptase for the confirmation of shrimp-induced anaphylaxis.

Successful wheat-specific oral immunotherapy in highly sensitive individuals with a novel multirush/maintenance regimen

We reported a successful oral immunotherapy (OIT) in 2 children with high wheat sensitivity (4 and 14 years old boys). Oral challenges indicated eliciting doses of 300 mg, and wheat flour of 30 mg. The OIT protocol includes 5 days of build-up phase in the hospital, intervening with 2 to 5 months of home maintenance phase. Patients could tolerate 45 g, and 60 g of wheat flour per day, respectively. We have demonstrated that OIT to a large amount of wheat in extremely sensitized patients could be achieved with a stepwise multi oral/maintenance regimen.

The Effect of Vitamin D Status on Pediatric Asthma at a University Hospital, Thailand

PURPOSE: In the USA and Europe, hypovitaminosis D is associated with increased asthma severity, emergency department (ED) visit, and impaired pulmonary function in asthmatic patients. However, in tropical countries, data on the effect of vitamin D status on asthma is limited. This study evaluates the relationship between vitamin D status and the level of asthma control as well as other asthmatic parameters. METHODS: Asthmatic children were evaluated for serum 25-hydroxyvitamin D, pulmonary function tests, a skin prick test, and the level of asthma control. RESULTS: A total of 125 asthmatic children were recruited (boys, 66.4%). Their mean age+/-SD was 10.8+/-3.0 years. Vitamin D statuses were: deficiency (30 ng/mL) in 36%. The vitamin D levels were 25.9+/-9.4 ng/mL in uncontrolled patients, 29.2+/-8.6 ng/mL in partly controlled patients, and 27.9+/-8.0 ng/mL in controlled patients (P>0.05). There were no significant differences in pulmonary function, asthma exacerbation, inhaled-corticosteroid (ICS) dose, anti-inflammatory drugs, or ED visit or hospitalization between different vitamin D statuses. Vitamin D deficiency patients were older and had a delayed onset of asthma than insufficiency or sufficiency patients. There was no significant correlation between serum vitamin D and pulmonary function/doses of ICS. CONCLUSIONS: High prevalences of vitamin D deficiency and insufficiency were found in asthmatic children in Thailand; however, there was no significant relationship between vitamin D status and the level of asthma control or other asthma parameters.

Progress in the management of childhood asthma

Asthma has become the most common chronic disease in childhood. Significant advances in epidemiological research as well as in therapy of pediatric asthma have been made over the past 2 decades. In this review, we look at certain aspects therapy of childhood asthma, both in the past and present. Literature review on allergen avoidance (including mites, cockroach and cat), intensive therapy with β₂-agonists in acute asthma (administering via continuous nebulization and intravenous routes), a revisit of theophylline use and its action, the use of inhaled corticosteroids in various phases of childhood asthma and sublingual immunotherapy in asthma are examined. Recent facts and dilemmas of these treatments are identified along with expression of our opinions, particularly on points of childhood asthma in the Asia-Pacific, are made in this review.

Epidemiology of childhood asthma in Asia / 천식및알레르기

Asthma is the most common chronic disease in childhood. Over the past 30 years, prevalence of childhood asthma has increased several folds throughout the world. In Asia, such increase has been observed in series of studies from South Korea, Taiwan, Thailand and Singapore as had been observed in industrialized countries. Available epidemiologic studies in Asia indicated that allergen exposure is the major risk factor for the development of childhood asthma. House dust mites and cockroaches are the major allergens sensitized by asthmatic children in Asia. Despite increasing evidence to support the popular 'Hygiene Hypothesis' in explaining the increase of allergic diseases in Europe and USA, results from limited studies in Asia are quite controversial. It is established that prevalence of childhood asthma is low among those residing in mainland China as compared to those living in Hong Kong. Nevertheless, recent studies on BCG vaccination from Hong Kong and Thailand did not indicate any difference in prevalence of allergic disease between children with/without significant tuberculin reactions. Limited information on smoking and breastfeeding exists from the region. A study from Japan indicated that breastfeeding was found not to exert a protective effect for the development of childhood asthma. In environment with multiple ethnicities such as in Asia, there is a great opportunity for a collaborative research on epidemiology of childhood asthma. The success of which will bring about further understanding on pathogenesis of asthma and on the increasing prevalence of allergic diseases in this region.