Clinical phenotype and allergen sensitization in the first 2 years as predictors of atopic disorders at age 5 years.

INTRODUCTION: From a birth cohort of at-risk Asian infants, we prospectively investigated the role of early onset allergen sensitization and clinical phenotypes as risk factors for atopic disorders at the age of 5 years. METHODS AND MATERIALS: The study recruited 253 families with a history of allergic disease in a first degree relative from an antenatal clinic in Singapore. The children were followed prospectively to assess clinical outcomes and skin prick test was performed at 2 and 5 years of age. RESULTS: Allergen sensitization (food and/or house dust mites) alone at 2 years of age was not associated with increased risk of wheeze and eczema at 5 years. However, the clinical phenotype (eczema and wheeze) with or without the presence of concomitant allergen sensitization at 2 years increased this risk. For eczema, eczema alone at year 2 increased the risk of eczema at year 5 (adjOR = 7.1; 95 % CI: 1.8-27.8) and this was further increased by the presence of allergen sensitization (adjOR = 25.4; 95 % CI: 4.7-138.5) and the concomitant presence of both wheeze and allergen sensitization (adjOR = 64.9; 95 % CI: 4.7-900.0). For wheeze, wheeze alone at 2 years (adjOR = 4.5; 95 % CI: 1.4 -14.8), and wheeze with concomitant allergen sensitization and eczema (adjOR = 13.9; 95 % CI: 1.2-168.5) increased the risk of wheeze at 5 years. The exception was rhinitis, where allergen sensitization alone at 2 years (adjOR = 5.6; 95 % CI: 1.1-29.2) increased the risk of rhinitis at 5 years. Early onset of eczema at 2 years also increased the risk of rhinitis (adjOR = 6.8; 95 % CI: 2.0-23.1). CONCLUSION: In this Asian birth cohort, the clinical phenotype (eczema and wheeze) with or without concomitant allergen sensitization in the first 2 years of life were strong predictors of atopic disorders at 5 years.

Clinical characteristics and outcomes of patients undergoing drug provocation tests (DPTs).

INTRODUCTION: Patients who have an adverse drug reaction are frequently labelled drug allergic without undergoing proper evaluation and confirmatory testing. These drug allergy labels may be inaccurate, leading to unnecessary lifelong avoidance. The aim of this study was to review the patients that underwent drug provocation tests (DPTs) in our centre and examine the usefulness of DPTs in confirming or rejecting a diagnosis of drug hypersensitivity. MATERIALS AND METHODS: The study design was a retrospective chart review of all adult patients who underwent drug provocation in the allergy unit at the National University Hospital, Singapore, for single or multiple suspected drug allergies from the period January 2009 to June 2011. RESULTS: Eighty-seven patients underwent 123 DPTs (median age 41; interquartile range 28 to 50). Twenty-one patients underwent multiple DPTs. The most common culprit drugs reported were antibiotics (43.9%) of which beta-lactams were implicated in 75.9% of the cases. This was followed by non-steroidal anti-inflammatory drugs (NSAIDS) in 15.4%, paracetamol in 7.3% and both NSAIDs and paracetamol in 3.3%. Rash was the most commonly reported symptom (41.5%), followed by angioedema (32.5%), anaphylaxis (9.8%), and other symptoms including respiratory (2.4%), gastrointestinal (0.8%) and others (13.0%). The majority of DPTs were performed to antibiotics (43.9%), NSAIDs (19.5%) and paracetamol (6.5%). DPTs were negative in 93.5% of subjects and positive in 6.5%. Of the 8 positive DPTs, none had a serious reaction, with 5 patients requiring rescue therapy, which comprised solely of oral antihistamines. CONCLUSION: Suspected drug hypersensitivity is common but true drug allergy is rare. DPTs remain the gold standard and should be included as part of an investigative protocol. DPTs are a safe and valuable diagnostic tool in the hands of the experienced clinician.

Etoricoxib: a safe alternative for NSAID intolerance in Asian patients.

BACKGROUND: NSAID intolerance is not uncommon. Etoricoxib, a cox-2 inhibitor NSAID, has been shown to be a safe alternative in these patients. This study aims to determine the rate of NSAID intolerant patients who are able to tolerate etoricoxib without adverse reactions. METHODS: This study analyzed charts and electronic databases of all patients referred to the allergy clinics of the National University Hospital and Gleneagles Hospital in Singapore from 2006-2011 for oral provocation tests to etoricoxib (cumulative dose of 120 mg), on the background of NSAID intolerance. Demographics, atopic comorbidities, history of chronic urticaria, inciting NSAID, onset and type of reaction, and provocation test outcomes were obtained. RESULTS: A total of 74 patients (mean age 37; range: 16-72 years) underwent provocation tests to etoricoxib. Of these, 59% were female. Majority were Chinese (69%), followed by Malay (12%), Caucasian (8%), Indian (5%) and various other races (6%). Forty-six percent of the study population had atopic comorbidities, and 4% had concomitant chronic urticaria. Eighty percent of patients had a history of intolerance to 1 NSAID, while the rest (20%) had intolerance to multiple NSAIDS. Forty-one percent of patients had concomitant acetaminophen intolerance. Some of the patients had multiple symptoms on presentation, the most common of which were periorbital and facial edema (90%), breathing difficulties (26%) and urticaria (25%), with the onset of reaction occurring mostly within 30 minutes to 1 hour. Etoricoxib was tolerated in 95% of the patients. Subjects who reacted to the challenge all had mild reactions which resolved with antihistamines. CONCLUSIONS: Etoricoxib is a safe alternative in NSAID intolerant patients. Nevertheless, it is advised that patients should undergo provocation tests to confirm tolerance.

Anaphylaxis to cow's milk formula containing short-chain galacto-oligosaccharide.

BACKGROUND: On the basis of the proven prebiotic effects of oligosaccharides in cow's milk formula (CMF) in infants, CMFs are supplemented with oligosaccharides. OBJECTIVE: We present a series of 5 cases of cow's milk-tolerant but atopic patients with a history of respiratory allergies. All had anaphylaxis after the ingestion of CMF supplemented with short-chain galacto-oligosaccharide (scGOS). The allergen trigger was investigated. METHODS: Clinical histories were collated. Skin prick tests (SPTs) and basophil activation tests (BATs) were carried out with the eliciting CMF that triggered anaphylaxis, with or without supplemented prebiotics (scGOS) and with scGOS fractions containing oligosaccharides of different chain lengths. RESULTS: The median age of presentation was 6 years (range, 5-38 years). Anaphylaxis occurred within 30 minutes of the first known exposure to CMF supplemented with prebiotics in all patients. Only 1 patient was subjected to oral challenge, which resulted in an anaphylactic reaction. All patients demonstrated IgE sensitization through SPTs and BATs to scGOS and fractions of scGOS containing 3 sugar units or greater but not to cow's milk or long-chain fructo-oligosaccharide. Eight child control subjects tolerant to regular ingestion of scGOS-supplemented CMF and 1 adult volunteer were found to have negative results to scGOS through SPTs and BATs. In addition, in vitro BATs with donor basophils sensitized with sera from 2 of the 3 reported cases showed reactions to scGOS. The scGOS-induced basophil activation was inhibited in the presence of wortmannin, a phosphatidylinositol 3-kinase inhibitor. CONCLUSIONS: This study describes an unusual form of IgE-mediated anaphylaxis triggered by low-molecular-weight oligosaccharides in scGOS. The primary sensitizer for this phenomenon requires further investigation.

A population-based study of fish allergy in the Philippines, Singapore and Thailand.

BACKGROUND: Fish allergy is the third most common food allergy after milk and egg in parts of Europe, but there is little data about prevalence in South East Asia where it is an important part of regular diets. OBJECTIVE: We aimed to obtain an estimate of the population prevalence of fish allergy among older children in the Philippines, Singapore and Thailand. METHODS: The population prevalence of fish allergy in 14- to 16-year-old children in the 3 countries was evaluated using a structured written questionnaire which was distributed to students of randomly selected secondary schools. An extended questionnaire to determine convincing fish allergy on the basis of typical clinical manifestations within 2 h of ingestion was administered to those with positive responses. RESULTS: From a cohort of 25,842 students, responses were 81.1% in the Philippines (n = 11,434), 67.9% in Singapore (n = 6,498) and 80.2% (n = 2,034) in Thailand. Using criteria for convincing food allergy, fish allergy was much higher in the Philippines [2.29%, 95% confidence interval (CI) 2.02-2.56] than in Singapore (0.26%, 95% CI 0.14-0.79) and Thailand (0.29%, 95% CI 0.06-0.52). Weighted multiple logistic regression analyses showed that compared to the Philippines, prevalence rates were lower in Singapore [odds ratio (OR) 0.40, 95% CI 0.27-0.60, p < 0.0001] and Thailand (OR 0.13, 95% CI 0.05-0.33, p < 0.0001). Females were more likely to have fish allergy compared to males for all children combined (OR 1.32, 95% CI 1.11-1.58, p = 0.002). Most allergies appeared mild, as only 28% of cases sought medical consultation at the time of the reaction and 31.2% of cases reported continued exposure despite allergic symptoms. CONCLUSION: Fish allergy in late childhood is more common in the Philippines compared to Singapore and Thailand. Differences in food processing, dietary habits and other cultural practices might be important risk factors for the development of fish allergy in these populations.

Shellfish allergy--an Asia-Pacific perspective.

BACKGROUND AND OBJECTIVE: Shellfish forms a common food source in the Asia-Pacific and is also growing in the West. This review aims to summarize the current literature on the epidemiology and research on shellfish allergy with particular focus on studies emerging from the Asia-Pacific region. DATA SOURCES: A PubMed search using search strategies "Shellfish AND Allergy", "Shellfish Allergy Asia", and "Shellfish AND anaphylaxis" was made. In all, 244 articles written in English were reviewed. RESULTS: Shellfish allergy in the Asia-Pacific ranks among the highest in the world and is the most common cause of food-induced anaphylaxis. Shellfish are classified into molluscs and arthropods. Of the arthropods, the crustaceans in particular Penaeid prawns are the most common cause of allergy and are therefore most extensively studied. Several classes of allergens have been identified. The tropomyosins (class 1 allergens) are the best defined. Despite the establishment of molecular homology and allergenic cross reactivity between allergens of the same class, clinical cross-reactivity is more variable between patients and less clearly defined. There are two relatively unique clinical manifestations of IgE-mediated prawn allergy: (1) isolated oral allergy symptoms; and (2) wide spectrum of severity and sometimes even within the same individual. CONCLUSION: Shellfish allergy is common in the Asia Pacific. More research including food challenge-proven subjects are required to establish the true prevalence, as well as to understand clinical cross reactivity and variations in clinical features.

A population-based questionnaire survey on the prevalence of peanut, tree nut, and shellfish allergy in 2 Asian populations.

BACKGROUND: There has been a substantial increase in the prevalence of peanut and tree nut allergy in Western populations in the last 2 decades. However, there is an impression that peanut and tree nut allergy is relatively uncommon in Asia. OBJECTIVE: To evaluate the prevalence of peanut, tree nut, and shellfish allergy in schoolchildren in 2 Asian countries (Singapore and Philippines). METHODS: A structured written questionnaire was administered to local and expatriate Singapore (4-6 and 14-16 years old) and Philippine (14-16 years old) schoolchildren. RESULTS: A total of 25,692 schoolchildren responded to the survey (response rate, 74.2%). Of these, 23,425 responses fell within the study protocol's 4 to 6 and 14 to 16 year age groups and were included in the analysis. The prevalence of convincing peanut and tree nut allergy were similar in both local Singapore (4-6 years, 0.64%, 0.28%; 14-16 years, 0.47%, 0.3%, respectively) and Philippine (14-16, 0.43%, 0.33%, respectively) schoolchildren, but was higher in the Singapore expatriates (4-6 years, 1.29%, 1.12%; 14-16 years, both 1.21%, respectively; 4-6 years, expatriates vs local Singaporeans: peanut, P = .019; tree nut, P = .0017; 14-16 years, P > .05). Conversely, shellfish allergy was more common in the local Singapore (4-6 years, 1.19%; 14-16 years, 5.23%) and Philippine (14-16 years, 5.12%) schoolchildren compared with expatriate children (4-6 years, 0.55%; 14-16 years, 0.96%; P < .001). When data were pooled, respondents born in Western countries were at higher risk of peanut (adjusted odds ratios [95% CIs]: 4-6 years, 3.47 [1.35-8.93]; 14-16 years, 5.56 [1.74-17.76]) and tree nut allergy (adjusted odds ratios [95% CIs]: 4-6 years, 10.40 [1.61-67.36]; 14-16 years, 3.53 [1.00-12.43]) compared with those born in Asia. CONCLUSION: This study substantiates the notion that peanut and tree nut allergy is relatively low in Asian children, and instead shellfish allergy predominates. Environmental factors that are yet to be defined are likely to contribute to these differences.

Childhood food allergy: a Singaporean perspective.

Food allergy is defined as reaction to a food which has an immunologic mechanism. Its prevalence is increasing in children globally and is therefore of increasing clinical importance. A useful clinical approach is to distinguish food allergic reactions by the timing of clinical reaction in relation to food exposure and classified as immediate (generally IgE-mediated) and delayed (generally non-IgE-mediated), with the exception of eczema and eosinophilic gastrointestinal disease, which, when associated with food allergy may be associated with either mechanism. This review is aimed at providing the clinician with a Singaporean perspective on the clinical approach and management of these disorders.

Allergies in Asia: differences in prevalence and management compared with western populations.

There is wide variability in the epidemiology and management of childhood asthma and related atopic diseases globally. Urbanized, affluent Western countries tend to have a higher prevalence of these diseases compared with Asian nations. However, recent studies have shown that the prevalence in Asia is increasing, although the rate of increase has slowed in the more developed Asian cities. Some possible causes for these differences are socioeconomic status, degree of urbanization, rates of infection, healthcare practices and genetic factors. Importantly, there are significant differences in the way asthma and allergic diseases are managed within Asia. This is of great concern because of the health implications, as these diseases are some of the most common chronic conditions that affect both adults and children. This review compares the differences in prevalence and management between Asia and the West, and discusses some of the possible reasons behind these variations.

Effect of probiotic supplementation in the first 6 months of life on specific antibody responses to infant Hepatitis B vaccination.

Probiotics have been shown to enhance specific immune responses to vaccines. We aim to assess the effect of probiotic supplementation on specific IgG antibody responses to Hepatitis B (HepB) vaccination in infants. Compared to controls, probiotic supplementation improved HepB surface antibody responses in subjects receiving monovalent doses of HepB vaccine at 0, 1 month and a DTPa-HepB combination vaccine at 6 months [placebo (n=28): 187.97 (180.70-195.24), probiotic (n=29): 345.70 (339.41-351.99)mIU/ml] (p=0.069), but not those who received 3 monovalent doses [placebo (n=68): 302.34 (296.31-308.37), probiotic (n=77): 302.06 (296.31-307.81)mIU/ml] (p=0.996). Probiotics may enhance specific antibody responses in infants receiving certain Hepatitis B vaccine schedules.

Food-dependent exercise-induced anaphylaxis - a review of 5 cases.

INTRODUCTION: Food-dependent exercise-induced anaphylaxis (FDEIA) is an uncommon and under-recognised syndrome that clinicians may not consider in a patient presenting with anaphylaxis. CLINICAL PICTURE: We describe here 5 patients aged 9 to 20 years old who presented at a local tertiary hospital over a 2-year period from August 2006 to July 2008. All presented with urticaria, 4 were hypotensive, 2 had angioedema and another 2 had dyspnoea. The symptoms occurred between 15 and 150 minutes (mean, 81) after exercising and consuming various food. All had consumed shellfish. All patients were admitted with the diagnosis of anaphylaxis of undefined aetiology. Diagnosis of FDEIA was only reached upon referral to an allergist. TREATMENT AND OUTCOME: Patients were treated with standard medicines for anaphylaxis including adrenaline, antihistamines, steroids and fluid flushes. Symptoms resolved in 2 to 3 days with no further episodes. At discharge, patients were prescribed epinephrine auto-injectors and given written anaphylaxis management plans. CONCLUSIONS: More public awareness and strategies to ensure accurate diagnosis and management of this condition are necessary.

Food allergy-lessons from Asia.

OBJECTIVE: : This is a review on published data available on food allergy in East Asia and a discussion on the insights that it offers. METHODS: : PubMed searches were made for terms food allergy and anaphylaxis, in combination with Asia. RESULTS: : There is a paucity of population-based prevalence studies on food allergy in Asia. Certain unique food allergens, such as buckwheat, chestnuts, chickpeas, bird's nest, and royal jelly, which are consumed extensively by certain Asian populations have resulted in clinical food allergy of little importance in other populations. Crustacean shellfish is of importance in this region relative to other common food allergens. The high consumption of these foods and possibly coupled with cross-reactive tropomyosins from dominant inhalant dust mite and cockroach allergens in this region may explain this phenomenon. In contrast, the prevalence of peanut allergy is relatively low in this region. The reasons for this difference are not apparent. However, this may be a reflection of the general reduced propensity in this region to allergic diseases as seen with asthma. CONCLUSIONS: : Further research on food allergy in Asia is warranted because it offers unique opportunities to further our understanding on the influence of population and environment.