Trends in Childhood Anaphylaxis in Singapore: 2015-2022.

BACKGROUND: There has been limited data regarding the incidence of anaphylaxis in Asia. We aim to describe patterns in patient characteristics, triggers and clinical presentation of childhood anaphylaxis in Singapore. METHODS: This was a retrospective review of emergency electronic medical records of children with anaphylaxis. Patients with the allergy-related diagnoses of anaphylaxis, angioedema, allergy and urticaria based on ICD-9 codes were screened. Cases fulfilling the World Allergy Organization criteria for anaphylaxis were included. RESULTS: A total of 1188 cases of anaphylaxis were identified with a median age of 6.3 years. Extrapolating data from the study sites, from 2015 to 2022, the incidence rate of childhood anaphylaxis emergency visits in Singapore doubled from 18.9 to 38.8 per 100,000 person-years, with an incidence rate ratio (IRR) of 2.06 (95% confidence interval [CI] 1.70-2.49). In 2022, the incidence rate of food anaphylaxis was 30.1 per 100,000 person-years, IRR 2.39 (95% CI 1.90-3.01) and drug anaphylaxis was 4.6 per 100,000 person-years, IRR 1.89 (95% CI 1.11-3.25). The incidence rate in children aged 0-4 years quadrupled during the study period. Common triggers were egg (10.4%), peanut (9.3%), tree nut (8.8%), milk (8%), shellfish (7.8%) and non-steroidal anti-inflammatory drug (4.4%). The majority (88.6%) of patients were treated with intramuscular adrenaline. Total number of allergy-related visits did not increase over time between 2015 and 2019. Rates of severe anaphylaxis, namely anaphylactic shock and admission to high-dependency and intensive care, did not increase over time, with a mean incidence of 1.6, IRR 0.85 (95% CI 0.40-1.83) and 0.7, IRR 1.77 (95% CI 0.54-5.76) per 100,000 person-years, respectively. CONCLUSION: While the number of emergency visits due to childhood anaphylaxis has increased, the number of cases of allergy-related visits, anaphylactic shock and anaphylaxis requiring high-dependency and intensive care did not rise.

Tolerance development in cow's milk-allergic infants receiving amino acid-based formula: A randomized controlled trial.

BACKGROUND: Tolerance development is an important clinical outcome for infants with cow's milk allergy. OBJECTIVE: This multicenter, prospective, randomized, double-blind, controlled clinical study (NTR3725) evaluated tolerance development to cow's milk (CM) and safety of an amino acid-based formula (AAF) including synbiotics (AAF-S) comprising prebiotic oligosaccharides (oligofructose, inulin) and probiotic Bifidobacterium breve M-16V in infants with confirmed IgE-mediated CM allergy. METHODS: Subjects aged ≤13 months with IgE-mediated CM allergy were randomized to receive AAF-S (n = 80) or AAF (n = 89) for 12 months. Stratification was based on CM skin prick test wheal size and study site. After 12 and 24 months, CM tolerance was evaluated by double-blind, placebo-controlled food challenge. A logistic regression model used the all-subjects randomized data set. RESULTS: At baseline, mean ± SD age was 9.36 ± 2.53 months. At 12 and 24 months, respectively, 49% and 62% of subjects were CM tolerant (AAF-S 45% and 64%; AAF 52% and 59%), and not differ significantly between groups. During the 12-month intervention, the number of subjects reporting at least 1 adverse event did not significantly differ between groups; however, fewer subjects required hospitalization due to serious adverse events categorized as infections in the AAF-S versus AAF group (9% vs 20%; P = .036). CONCLUSIONS: After 12 and 24 months, CM tolerance was not different between groups and was in line with natural outgrowth. Results suggest that during the intervention, fewer subjects receiving AAF-S required hospitalization due to infections.

IgE-mediated fish allergy in Singaporean children.

BACKGROUND: Fish is one of the common causes of food allergy and there is limited literature about fish allergy in Singapore. OBJECTIVE: We aimed to describe the demographics, clinical features, and natural history of children with IgE-mediated fish allergy. METHODS: A retrospective review was conducted for children diagnosed with fish allergy in a tertiary pediatric hospital in Singapore between 2015 and 2020. RESULTS: The diagnosis of fish allergy was made in 108 patients based on a convincing history of IgE-mediated allergic reaction and a positive skin prick test. The median age at first reaction was 12 months (range 6-168) with most reacting on first ingestion (62.0%). The most common fish causing reactions were threadfin (48.1%), salmon (33.3%) and cod (31.5%). Majority presented with cutaneous symptoms (97.2%). Anaphylaxis occurred in 6.5%. Five were mono-sensitized (4.6%), 77 were oligo-sensitized (71.3%) and 26 were polysensitized (24.1%). Most can tolerate another species of fish (75.9%), most commonly salmon (37.0%), tuna (24.1%) and cod (22.2%). Median duration of follow up was 24 months (range 0-176). Twenty-eight out of 108 children (25.9%) acquired natural tolerance to index fish at a median age of 60 months (range 18-159). CONCLUSIONS: Most children with fish allergy can tolerate at least one other species of fish and resolution of fish allergy is possible. Thus, it is important to follow-up with an allergist to evaluate which fish species can be included in their diet to avoid unnecessary dietary restrictions.

Use of multiple epinephrine doses in anaphylaxis: A systematic review and meta-analysis.

BACKGROUND: Regulatory bodies recommend that all patients at risk of anaphylaxis be prescribed 2 epinephrine autoinjectors, which they should carry at all times. This is in contrast to some guidelines. The proportion of anaphylaxis reactions that are treated with multiple doses of epinephrine has not been systematically evaluated. OBJECTIVE: Our aim was to undertake a systematic review and meta-analysis of published studies reporting epinephrine treatment for anaphylaxis in which data relating to the number of doses administered were available. METHODS: We searched the Medline, Embase, and Cochrane databases for relevant studies reporting at least 10 anaphylaxis events (due to food or venom) from 1946 until January 2020. Data were extracted in duplicate for the meta-analysis, and the risk of bias was assessed. The study was registered under the PROSPERO identifier CRD42017069109. RESULTS: A total of 86 studies (36,557 anaphylaxis events) met the inclusion criteria (20 of the studies [23%] were prospective studies; 64 [74%] reported reactions in the community, and 22 [26%] included food challenge data). Risk of bias was assessed as low in 50 studies. Overall, 7.7% of anaphylaxis events from any cause (95% CI = 6.4-9.1) were treated with multiple doses of epinephrine. When only epinephrine-treated reactions for which subsequent doses were administered by a health care professional were considered, 11.1% of food-induced reactions (95% CI = 9.4-13.2) and 17.1% of venom-induced reactions (95% CI = 11.3-25.0) were treated with more than 1 epinephrine dose. Heterogeneity was moderate to high in the meta-analyses, but at sensitivity analysis this estimate was not affected by study design or anaphylaxis definition. CONCLUSION: Around 1 in 10 anaphylaxis reactions are treated with more than 1 dose of epinephrine.

IgE-mediated cow's milk protein allergy in Singaporean children.

BACKGROUND: Cow's milk protein allergy (CMA) is the second most common food allergy in Singapore. However, there is limited data on local paediatric CMA. OBJECTIVE: We aimed to describe the demographics, clinical characteristics, natural history and diagnostic performance of skin prick test (SPT) and cow's milk-specific immunoglobulin E (CM-IgE) in Singaporean children diagnosed with IgE-mediated CMA. METHODS: A retrospective review of medical records was conducted for children with an SPT performed to cow's milk between 2011 and 2016. RESULTS: There were 355 patients included, 313 cow's milk allergic and 42 cow's milk tolerant. The median age of reaction was 6 months (IQR 4-8). The most common allergic presentation was cutaneous reactions, followed by gastrointestinal reactions. Six patients (1.9%) reported anaphylaxis at initial presentation and 16 children (5.1%) experienced anaphylaxis to cow's milk at least once in their lifetime. Most of the CMA patients (81.8%) acquired natural tolerance by 6 years old. SPT to cow's milk of ≥ 7 mm and CM-IgE of ≥ 13 kU/L showed good discriminative abilities in predicting a failed oral food challenge (OFC) outcome. CONCLUSIONS: CMA is a food allergy which commonly presents during infancy, and parents need to be aware of the likelihood of severe allergic reactions, including anaphylaxis. Prognosis for CMA is generally favourable. Future prospective cohort studies are required to better understand the natural history and better define the diagnostic cut-off values for allergy testing in our population.

Enzyme replacement therapy desensitization in a child with infantile onset Pompe disease.

BACKGROUND: Enzyme replacement therapy significantly reduces morbidity and mortality in patients with Pompe disease. Development of hypersensitivity reactions to enzyme replacement therapy is common and can adversely affect disease outcomes when treatment is halted or delayed. OBJECTIVE: Our institution reports a case of successful alglucosidase alfa enzyme replacement therapy desensitisation in a 9-year-old girl with infantile onset Pompe disease. METHODS: A desensitisation protocol was tailored to our patient with the help of a multidisciplinary team including the allergist, geneticist, nurses and pharmacists. RESULTS: For our patient, desensitisation was successful using a multi-step three-fold dose escalation protocol. CONCLUSIONS: Desensitisation is possible in individuals with hypersensitivity reactions to enzyme replacement. Desensitisation protocols need to be tailored according to the patient's needs and responses to find a protocol that is safe, effective and simple.

Household environmental microbiota influences early-life eczema development.

Exposure to a diverse microbial environment during pregnancy and early postnatal period is important in determining predisposition towards allergy. However, the effect of environmental microbiota exposure during preconception, pregnancy and postnatal life on development of allergy in the child has not been investigated so far. In the S-PRESTO (Singapore PREconception Study of long Term maternal and child Outcomes) cohort, we collected house dust during all three critical window periods and analysed microbial composition using 16S rRNA gene sequencing. At 6 and 18 months, the child was assessed for eczema by clinicians. In the eczema group, household environmental microbiota was characterized by presence of human-associated bacteria Actinomyces, Anaerococcus, Finegoldia, Micrococcus, Prevotella and Propionibacterium at all time points, suggesting their possible contributions to regulating host immunity and increasing the susceptibility to eczema. In the home environment of the control group, putative protective effect of an environmental microbe Planomicrobium (Planococcaceae family) was observed to be significantly higher than that in the eczema group. Network correlation analysis demonstrated inverse relationships between beneficial Planomicrobium and human-associated bacteria (Actinomyces, Anaerococcus, Finegoldia, Micrococcus, Prevotella and Propionibacterium). Exposure to natural environmental microbiota may be beneficial to modulate shed human-associated microbiota in an indoor environment.

Reaction phenotypes in IgE-mediated food allergy and anaphylaxis.

OBJECTIVE: Food allergy encompasses a range of food hypersensitivities. Different clinical phenotypes for food allergy likely exist in much the same way as endotype discovery is now a major research theme in asthma. We discuss the emerging evidence for different reaction phenotypes (ie, symptoms experienced after allergen exposure in food allergic individuals) and their relevance for clinical practice. DATA SOURCES: Published and unpublished literature relating to reaction phenotypes in food allergy. STUDY SELECTIONS: Authors assessment of the available data. RESULTS: Food anaphylaxis may be pathophysiologically different than anaphylaxis caused by nonfood triggers. Currently, there are no robust, clinically useful predictors of severity in food allergy. It is likely that patient-specific reaction phenotypes exist in food allergy, which may affect the risk of severe anaphylaxis. Allergen immunotherapy may modulate these phenotypes. CONCLUSION: Data are emerging to confirm our clinical experience that many food allergic patients experience stereotypical symptoms after allergen exposure, both in the community and at supervised oral food challenge, in a manner that varies among patients. Integrating data sets from different cohorts and applying unbiased machine-based learning analyses may demonstrate specific food allergy endotypes in a similar way to asthma. Whether this results in improvements in patient management (eg, through facilitating risk stratification or affecting the decision to prescribe an epinephrine autoinjector and, perhaps, the number of devices) remains to be determined, but given our current inability to predict which patients are most at risk of severe food allergic reactions, this will clearly be an important area of research in the future.

Cytokine release syndrome - a unique entity of Augmentin hypersensitivity reaction.

Cytokine release syndrome (CRS) is a type of hypersensitivity reaction which has been previously described with chemotherapy and monoclonal antibodies, but not with antibiotics. We present 2 pediatric cases of Amoxicillin/Clavulanic acid (Augmentin) anaphylaxis resembling CRS. Both our patients presented during the index reaction with symptoms suggestive of an acute systemic inflammatory response mimicking sepsis. Their symptomology was reproducible at drug provocation test as anaphylaxis, but with suboptimal response to intramuscular adrenaline. Their infective workups were unremarkable and illnesses followed a self-limiting course. All these point towards a severe hypersensitivity reaction resembling CRS.

Outcome of drug provocation testing in children with suspected beta-lactam hypersensitivity.

BACKGROUND: Suspicion of beta-lactam (BL) hypersensitivity is often based on parental report. Evaluation is important as incorrect labelling has clinical consequence. OBJECTIVE: To describe the outcomes of drug provocation test (DPT) in children with suspected hypersensitivity. METHODS: A retrospective study of patients who completed BL DPT from 1 August 2016 to 31 December 2017 at a paediatric allergy centre in Singapore. Suspected hypersensitivity reactions were classified as immediate (onset ≤1 hour) or delayed (onset > 1 hour). Patients with immediate reactions underwent skin prick test (SPT) followed by DPT if SPT was negative. Patients with delayed reactions underwent DPT directly. RESULTS: We identified 120 children who reported 121 suspected hypersensitivity reactions. The median age at reaction was 2.0 years (interquartile range [IQR], 1.0-5.0 years) and the median age at DPT was 7.4 years (IQR, 4.2-11.1 years). The timing of suspected hypersensitivity reaction was immediate in 21% (25 of 121), delayed in 66% (80 of 121), and uncertain in 13% (16 of 121). Commonly implicated drugs were amoxicillin in 45% (54 of 121), amoxicillin-clavulanate in 37% (45 of 121), and cephalexin in 8% (10 of 121). Commonly reported symptoms were maculopapular rash 44% (53 of 121), urticaria 34% (41 of 121), and angioedema 22% (27 of 121). All SPTs (n = 26) were negative. There were 118 diagnostic DPTs to index drug and 3 DPTs to alternative drug. A negative challenge result was obtained in 93% (110 of 118) of diagnostic DPTs: 92% (96 of 104) and 100% (14 of 14) of DPTs to penicillin group and cephalosporins respectively. All challenge reactions were mild. CONCLUSION: Our study supports the opinion that prior skin tests may not be necessary for children who report nonsevere reactions and directly performing diagnostic DPT is a safe approach in the evaluation of suspected childhood BL hypersensitivity.

Peanut Allergy - No Longer a Life Sentence.

In this review we provide an overview on the latest knowledge in the prevention and active management of peanut allergy. The rise in incidence of food allergy has generated new challenges in the management of affected individuals. Strategies to counteract the increase in prevalence of peanut allergy can be considered as a pyramid, beginning with primary prevention of those at risk through earlier introduction of peanut into the infant diet, to secondary prevention of peanut-sensitised children through improvements in the correct diagnosis of peanut allergy and finally to the treatment of children with proven peanut allergy. CONCLUSION: With the paradigm shift towards an active management, peanut allergy should no longer be seen as a life sentence.

A 5-year retrospective review of children with peanut allergy in the largest paediatric hospital in Singapore.

BACKGROUND: The prevalence of peanut allergy (PA) among children has increased significantly over the past decade. Even though the prevalence of PA in Singapore is considered low, peanut is the top trigger for food-induced anaphylaxis in Singaporean children. OBJECTIVE: To describe the demographic characteristics and clinical features of children with PA. METHODS: This is a 5-year retrospective review of children diagnosed with PA based on clinical history coupled with a positive skin prick test to peanut or positive oral food challenge results. RESULTS: There were 269 patients (53.9% males) with a clinical diagnosis of PA. The median age at first allergic presentation for the PA group was 24 months old, with interquartile range of 13-39 months. The most common form of peanut introduced was roasted peanut. The rate of peanut anaphylaxis was 7.1%. Concomitant tree nut sensitization was found in 32.3% of this cohort, predominantly to cashew nut. Majority of them have a personal history of atopy - 75.8% with eczema, 63.6% with allergic rhinitis, and 19.7% with asthma. CONCLUSION: This is the first large review of peanut-allergic children in Singapore. Prospective population-based studies are needed to establish the true prevalence and risk factors associated with the development of this potentially life-threatening condition.

Goat's milk anaphylaxis in a cow's milk tolerant child.

Goat's milk (GM) allergy commonly occurs together with cow's milk (CM) allergy due to cross-reactivity between highly homologous proteins. We present an unusual case of GM anaphylaxis in a CM tolerant child.

Predictive value of peanut skin prick test, specific IgE in peanut-sensitized children in Singapore.

BACKGROUND: The predictive decision points for both peanut skin prick test (SPT) wheal size and serum IgE concentrations, in peanut-sensitized children, have not been evaluated in Singapore. OBJECTIVE: We aim to derive clinically useful predictive decision points to be used for risk stratification of oral food challenge (OFC) in peanut-sensitized patients. METHODS: Patients with a positive SPT to peanut, performed during a 4-year period between 2012 and 2016, were included in a retrospective chart review. The patients were assessed for their peanut allergy status based on a convincing clinical history. Their first SPT and serum IgE results done at presentation to our centre were used. RESULTS: There were 269 patients with a clinical diagnosis of peanut allergy based on recent immediate reaction to peanut and 59 patients whom were tolerating peanuts regularly. There were 251 patients sensitized to peanut, without prior known peanut exposure. A wheal size of ≥8 mm and a peanut-specific IgE of ≥6 kU/L each provided for a 95% positive predictive value of clinical reaction to peanuts; the larger the wheal size on SPT, the higher the probability. CONCLUSION: The cutoff values derived in this study can help clinicians in the risk assessment of OFC in peanut-sensitized patients. Prospective studies using OFCs for the diagnosis of peanut allergy are needed to confirm the diagnostic performance of these tests in predicting OFC outcomes.

An unusual case of infant seizures with anaphylaxis to wheat.

Wheat allergy is one of the commonest food allergies in childhood and it typically presents with IgE mediated reactions, including anaphylaxis. Seizures are not typically reported to be a direct manifestation of anaphylaxis, though it can occur secondary to hypoxia following significant haemodynamic compromise. We describe a case of a previously well infant, who presented with anaphylactic shock to wheat and responded well to the initial management, but subsequently developed a cluster of brief generalised tonic clonic seizures without any ongoing haemodynamic instability. The tryptase level that was performed at 4-5 hours post reaction was raised at 49.1 µg/L. Skin prick test to wheat, wheat specific IgE, the omega-5 gliadin IgE were positive. Extensive work-up was performed to look for an underlying cause of seizures and all returned negative. To our knowledge, this is the first case report describing an unusual presentation of multiple seizures in a young infant, in association with an anaphylactic episode. In the absence of any other seizure provoking factor and underlying cause, we believe the association is more likely causative than coincidental.

Growth of children with food allergies in Singapore.

BACKGROUND: Although it is known that children with food allergies are at risk of impaired growth, this has not been well studied in South-East Asia. OBJECTIVE: The aim of this cross-sectional study is to survey the growth of children with food allergies in Singapore and the factors impacting it. METHODS: Anthropometric data, demographic data, type of food allergy, foods eliminated, and atopic comorbidities were recorded. Malnutrition was defined using World Health Organization standards (≤-2 z-score for weight-for-height [WH], weight-for-age [WA], and height-for-age [HA]). RESULTS: Seventy-four patients (51% male) were recruited over 1 month, with median age at diagnosis of 8 months (interquartile range [IQR], 4-13 months) and at data collection of 25 months (IQR, 14-48 months). Sixty-two (84%) had IgE-mediated allergy, 8 (11%) mixed IgE and non-IgE, and 4 (5%) non-IgE-mediated allergy. Food exclusions: 55% one food, 27% two foods, 8% three to four foods, and 10% ≥5 foods. Only 1% were underweight (WA ≤ -2 z-score) and 3% had WA ≥ +2 z-score. Having a mixed type food allergy significantly reduced WA (p = 0.023). WA was significantly lower for those referred to the dietitian (p = 0.027). 5.4% were stunted (HA ≤ -2 z-score). Factors significantly associated with stunting were underlying eczema (p = 0.03) and having an IgE-mediated (p = 0.03) or mixed type food allergy (p = 0.002). One point four percent (1.4%) were undernourished (WH ≤ -2 z-score) and 1.4% were overweight (WH ≥ +2 z-score). Multivariate regression analysis found that children with mixed type food allergies were significantly shorter (z-score -1 lower). Children had a lower WA if they had skin involvement as part of their symptom presentation. CONCLUSION: This is the first survey documenting growth in children with food allergy in Singapore. Eczema, IgE-mediated and mixed type allergies are associated with poorer growth rates in these children. Early, individualised nutritional intervention is recommended for all children with food allergy.