Is asthma in children still increasing? 20-year prevalence trends in northern Sweden.

BACKGROUND: In the present study, we describe prevalence trends of asthma and investigate the association with asthma symptoms, use of asthma medication, and asthma severity among 8-year-old children in Norrbotten, Sweden in 1996, 2006, and 2017. METHODS: Within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, three pediatric cohorts were recruited in 1996, 2006, and 2017 respectively. Identical methods were used; all children in first and second grade (median age 8 years) in three municipalities were invited to a parental questionnaire survey, completed by n = 3430 in 1996 (97% participation), n = 2585 in 2006 (96%), and n = 2785 in 2017 (91%). The questionnaire included questions about respiratory symptoms and diagnosis, treatment, and severity of asthma. RESULTS: The prevalence of wheezing was stable during the study, 10.1% in 1996; 10.8% in 2006; and 10.3% in 2017, p = .621, while physician-diagnosed asthma increased: 5.7%, 7.4%, and 12.2%, p < .001. The use of asthma medication in the last 12 months increased: 7.1%, 8.7%, and 11.5%, p < .001. Among children diagnosed with asthma, the prevalence of asthma symptoms, the impact on daily life, and severe asthma decreased, while the use of inhaled corticosteroids increased from 1996 until 2017. CONCLUSION: The prevalence of wheezing was stable among 8-year-old in this area from 1996 to 2017, while the prevalence of physician-diagnosed asthma doubled but without an increase in asthma morbidity. The increase of physician-diagnosed asthma without a coincident increase in asthma morbidity can partly be explained by more and earlier diagnosis among those with mild asthma.

Diagnostic intervention improved health-related quality of life among teenagers with food allergy.

OBJECTIVES: The aim was to examine if a diagnostic intervention set up to assess current food allergy to cow's milk, hen's egg, fish, or wheat among teenagers had an impact on generic and disease specific health-related quality of life (HRQL). The study compared HRQL scoring before and two years after the intervention, and in relation to age matched controls without reported food allergy. METHODS: The study was performed within the Obstructive Lung Disease in Northern Sweden (OLIN) studies where a cohort study on asthma and allergic diseases among 8-year-old schoolchildren was initiated in 2006. At age 12 years, the 125/2612 (5%) children who reported allergy to cow's milk, hen's egg, fish, or wheat were invited to a diagnostic intervention including clinical examination, blood tests and evaluation by a pediatric allergist. Of 94 participants, 79 completed generic and disease specific HRQL questionnaires. Additionally, a random sample of 200 (62% of invited) children without food allergy from the OLIN cohort answered the generic HRQL questionnaire. The respondents of the HRQL questionnaires were re-examined two years later and 57 teenagers with and 154 without reported allergy participated. RESULTS: There were no significant differences in generic HRQL scores between teenagers with and without reported food allergy at study entry, or after the intervention. Among those with reported food allergy, we found a significant improvement in disease specific HRQL after the intervention (mean values: 3.41 vs 2.80, p<0.001). Teenagers with only food allergy had better disease specific HRQL compared to those with one, two or three concomitant allergic diseases, both before and after the intervention. Children with only food allergy significantly improved their HRQL after the intervention, 1.84 vs. 2.87 (p<0.001) but this association was not seen in children with one other allergic disorder (3.16 vs. 3.65, p = 0.121) or those with two or more allergic disorders (3.72 vs. 3.90, p = 0.148). CONCLUSION: The diagnostic intervention showed a long-term improvement of disease specific HRQL but not generic HRQL.

Decreasing prevalence of atopic dermatitis in Swedish schoolchildren: three repeated population-based surveys.

BACKGROUND: The prevalence of atopic dermatitis (AD) has increased over several decades and now affects about one-fifth of all children in high-income countries (HICs). While the increase continues in lower-income countries, the prevalence of AD might have reached a plateau in HICs. OBJECTIVES: To investigate trends in the prevalence of AD and atopic comorbidity in schoolchildren in Sweden. METHODS: The study population consisted of three cohorts of children (median age 8 years) in Norrbotten, Sweden, for 1996 (n = 3430), 2006 (n = 2585) and 2017 (n = 2785). An identical questionnaire that included questions from the International Study of Asthma and Allergies in Childhood (ISAAC) protocol was used in all three cohorts. Trends in AD prevalence were estimated, as well as trends in atopic comorbidity. AD prevalence was estimated both according to the ISAAC definition of AD and by adding the reported diagnosis by a physician (D-AD). RESULTS: The prevalence of AD decreased in the last decade, from 22.8% (1996) and 21.3% (2006) to 16.3% (2017; P < 0.001). The prevalence of D-AD was lower, but the same pattern of decrease was seen, from 9.3% (1996) and 9.4% (2006) to 5.7% (2017; P < 0.001). In all three cohorts, AD was more common among girls than boys (18.9% vs. 13.8% in 2017; P < 0.001). Children from the mountain inlands had a higher prevalence of AD than children from coastal cities (22.0% vs. 15.1% in 2017; P < 0.001). In comparing D-AD, there were no significant differences between the sexes or between inland or coastal living. Concomitant asthma increased over the years from 12.2% (1996) to 15.8% (2006) to 23.0% (2017; P < 0.001). Concomitant allergic rhinitis and allergic sensitization increased from 1996 (15.0% and 27.5%) to 2006 (24.7% and 49.5%) but then levelled off until 2017 (21.0% and 46.7%). CONCLUSIONS: The prevalence of AD among schoolchildren in Sweden decreased over the study period, whereas atopic comorbidity among children with AD increased. Although a decrease was seen, AD is still common and the increase in atopic comorbidity among children with AD, especially the increase in asthma, is concerning.

Revised Swedish infant feeding guidelines are associated with earlier introduction of allergenic foods.

BACKGROUND: Randomized controlled trials have demonstrated that early introduction of allergenic foods, such as peanut and egg, can reduce food allergy in high-risk children. Many international guidelines recommend introduction of allergenic foods in the first year of life, and accordingly, the Swedish National Food agency released updated guidelines in June 2019. OBJECTIVE: Our aim was to examine whether the age at introduction and consumption frequency of allergenic foods have changed since release of the revised national guidelines on the introduction of solid foods in Sweden. METHODS: Children born between June 2016 and December 2018 (n = 1925) were compared with children born between June 2019 and April 2021 (n = 1761) by using data from the NorthPop Birth Cohort study. Data on food introduction, eczema, and food allergy were prospectively collected until age 18 months by using web-based questionnaires. IgE sensitization was assessed at 18 age months. RESULTS: The proportion of participants who had been introduced to egg, legume, soy products, peanut, almond, and cashew nut during the first year of life increased after implementation of the revised national guidelines. The most significant changes were seen for legume (from 55.2% to 69.8% [adjusted odds ratio = 1.90 (95% CI = 1.62-2.24)]) and peanut (from 29.2% to 43.2% adjusted odds ratio = 1.87 (95% CI = 1.55-2.24)]); consumption frequency had also increased. No differences in the prevalence of eczema, food allergy, or sensitization to the foods of interest were found. CONCLUSION: Since release of the revised guidelines, infants in the general population are introduced to and consume a variety of allergenic foods earlier and more frequently; however, early manifestations of allergic disease have remained unchanged.

Prevalence and risk factors for allergic sensitization: 3 cross-sectional studies among schoolchildren from 1996 to 2017.

Background: The prevalence of allergic sensitization and allergic diseases has increased for decades in Northern Europe, but recent studies are lacking. Objective: We sought to study the prevalence trends of allergic sensitization, associated risk factors, and the association with asthma and allergic rhinitis (AR) among children in Northern Sweden. Methods: Three cohorts of children aged 7 to 8 years participated in a skin prick test (SPT) with 10 airborne allergens in 1996, 2006, and 2017, with 2148, 1693, and 1762 participants tested, respectively, representing 87% to 90% of schoolchildren in the catchment communities. Adjusted Poisson regression was used to identify risk factors for allergic sensitization and the association with asthma and AR. Results: The prevalence of any positive SPT response increased from 21% in 1996 to 30% in 2006 and remained at 30% in 2017 (P < .001). Sensitization to cat was the most common for all the years. The risk factor pattern for a positive SPT response was similar in all examinations, with positive and significant associations with a family history of allergy (risk ratio, 1.4-1.5) and negative and significant associations with having a cat at home (risk ratio, 0.7-0.8). The prevalence of physician-diagnosed asthma increased, but the association with allergic sensitization weakened. The opposite trends were found for AR-decreasing prevalence and strengthened association with allergic sensitization. Conclusions: The prevalence of allergic sensitization increased from 1996 to 2006 but plateaued in the next decade, whereas the risk factor pattern remained stable. The diverging trends of associations between allergic sensitization and asthma and AR suggest secular trends in the clinical management of allergic diseases.

Food protein-induced enterocolitis syndrome among children in northern Sweden-A retrospective review from 2004-2018.

AIM: To describe clinical presentation and development of tolerance among children with Food protein-induced enterocolitis syndrome (FPIES) in a population in northern Sweden. METHODS: A retrospective review of medical records of children presenting with FPIES symptoms from 1 January 2004, to 31 May 2018. RESULTS: Sixty children (65% boys) with FPIES were included. The estimated incidence gradually increased to 0.45% in 2016-2017. The most common food triggers were cow's milk (40%), fish (37%) and oat (23%). Symptoms presented in 31 (60%) children before 6 months and in 57 (95%) before 1 year of age. The median age for FPIES diagnosis was 7 (range 3-134) months and for fish FPIES 13 (range 7-134) months. By 3 years of age, 67% of children with FPIES to milk and oat but none of the children with fish FPIES had developed tolerance. Allergic conditions like eczema and asthma were reported in 52% of the children. CONCLUSION: The cumulative FPIES incidence was 0.45% in 2016-2017. Most children presented with symptoms before 1 year of age, but the diagnosis was often delayed, especially for FPIES to fish. Tolerance development occurred at an earlier age when FPIES was triggered by milk and oat compared to fish.

The Majority of Children Sensitized Before School-Age Develop Allergic Disease Before Adulthood: A Longitudinal Population-Based Study.

BACKGROUND: Allergic sensitization increases the risk of asthma and allergic rhinitis, but the impact of age at onset of sensitization is less studied. OBJECTIVE: To examine the cumulative incidence of asthma and rhinitis up to age 19 years in relation to age at onset of sensitization to airborne allergens. METHOD: All children in grade 1 and 2 (median age, 8 years) in 2 municipalities in Northern Sweden were invited to undergo skin prick tests and answer a questionnaire about allergic diseases, and 88% participated. At ages 12 and 19 years, the protocol was repeated, and 1510 individuals participated in all 3 examinations. Specific IgE data were collected in a random sample at age 19 years (n = 770). Onset of sensitization was defined: 8 years or less, 8 to 12 years, 12 to 19 years, and never sensitized. Adjusted Poisson regression was used to calculate risk ratios (RRs). RESULTS: At 19 years, those sensitized at 8 years of age or earlier had the highest risk of asthma (RR, 4.68; 95% CI, 3.15-6.97) and rhinitis (RR, 22.3; 95% CI, 13.3-37.6), and 84% had developed either asthma or rhinitis. The combination of sensitization at age 8 years or earlier and family history of allergic diseases rendered high risks for asthma (RR, 10.6; 95% CI, 6.71-16.7) and rhinitis (RR, 36.3; 95% CI, 18.9-69.7). Individuals sensitized at age 8 years or earlier showed significantly highest level of sensitization, as judged by number of positive skin test results and titers of specific IgE. CONCLUSIONS: Most individuals with sensitization at age 8 years or earlier developed asthma or rhinitis before young adulthood. The high level of sensitization in those sensitized early contributes to the high incidence of allergic airway conditions.

IGF1, serum glucose, and retinopathy of prematurity in extremely preterm infants.

BACKGROUNDHyperglycemia, insulin insensitivity, and low IGF1 levels in extremely preterm infants are associated with an increased risk of retinopathy of prematurity (ROP), but the interactions are incompletely understood.METHODSIn 117 extremely preterm infants, serum glucose levels and parenteral glucose intake were recoded daily in the first postnatal week. Serum IGF1 levels were measured weekly. Mice with oxygen-induced retinopathy alone versus oxygen-induced retinopathy plus streptozotocin-induced hyperglycemia/hypoinsulinemia were assessed for glucose, insulin, IGF1, IGFBP1, and IGFBP3 in blood and liver. Recombinant human IGF1 was injected to assess the effect on glucose and retinopathy.RESULTSThe highest mean plasma glucose tertile of infants positively correlated with parenteral glucose intake [r(39) = 0.67, P < 0.0001]. IGF1 plasma levels were lower in the high tertile compared with those in low and intermediate tertiles at day 28 (P = 0.038 and P = 0.03). In high versus lower glucose tertiles, ROP was more prevalent (34 of 39 versus 19 of 39) and more severe (ROP stage 3 or higher; 71% versus 32%). In oxygen-induced retinopathy, hyperglycemia/hypoinsulinemia decreased liver IGF1 expression (P < 0.0001); rh-IGF1 treatment improved normal vascular regrowth (P = 0.027) and reduced neovascularization (P < 0.0001).CONCLUSIONIn extremely preterm infants, high early postnatal plasma glucose levels and signs of insulin insensitivity were associated with lower IGF1 levels and increased ROP severity. In a hyperglycemia retinopathy mouse model, decreased insulin signaling suppressed liver IGF1 production, lowered serum IGF1 levels, and increased neovascularization. IGF1 supplementation improved retinal revascularization and decreased pathological neovascularization. The data support IGF1 as a potential treatment for prevention of ROP.TRIAL REGISTRATIONClinicalTrials.gov NCT02760472 (Donna Mega).FUNDINGThis study has been supported by the Swedish Medical Research Council (14940, 4732, 20144-01-3, and 21144-01-3), a Swedish government grant (ALFGB2770), Lund medical faculty grants (ALFL, 11615 and 11601), the Skåne Council Foundation for Research and Development, the Linnéa and Josef Carlsson Foundation, the Knut and Alice Wallenberg Foundation, the NIH/National Eye Institute (EY022275, EY017017, EY017017-13S1, and P01 HD18655), European Commission FP7 project 305485 PREVENT-ROP, Deutsche Forschungsgemeinschaft (CA-1940/1-1), and Stiftelsen De Blindas Vänner.

Lung function after extremely preterm birth-A population-based cohort study (EXPRESS).

BACKGROUND AND OBJECTIVES: Follow-up studies of children and young adults born very-to-moderately preterm show persistent and significant lung function deficits. The aim of the study was to determine lung function and airway mechanics in school-aged children born in 2004 to 2007 and extremely preterm (after 22-26 weeks of gestation). METHODS: In a population-based cohort of children born extremely preterm and controls born at term (n = 350), follow-up at 6½-years-of-age was performed using spirometry and impulse oscillometry. Associations to gestational age, smallness for gestational age (SGA), and bronchopulmonary dysplasia (BPD) were assessed. RESULTS: Children born extremely preterm had lower forced vital capacity (FVC, z-score: -0.7, 95%CI: -1.0;-0.4), forced expiratory volume (FEV1 , z-score: -1.1, 95%CI: -1.4; -0.8), higher frequency-dependence of resistance (R5-20 , 0.09, 95%CI: 0.05; 0.12 kPa · L-1 · s-1 ) and larger area under the reactance curve (AX, 0.78, 95%CI: 0.49; 1.07 kPa · L-1 ) than controls. In children born at 22-24 weeks of gestation, 24% had FVC and 44% had FEV1 below the lower limit of normal. SGA and severe BPD only marginally contributed to pulmonary outcomes. Asthma-like disease was reported in 40% of extremely preterm children and 15% of controls. CONCLUSION: Many children born extremely preterm have altered airway mechanics and significant obstructive reduction in lung function. This warrants consideration for treatment and continued follow-up.

Health Related Quality of Life among schoolchildren aged 12-13 years in relation to food hypersensitivity phenotypes: a population-based study.

BACKGROUND: While Health Related Quality of Life has been investigated among children with IgE-mediated food allergy, less is known about quality of life among children with other types of hypersensitivity to food. The aim of this study was to investigate Health Related Quality of Life (HRQL) in children with and without food hypersensitivity. Further, we compared HRQL between children with different phenotypes of food hypersensitivity. METHODS: In a large population-based cohort of schoolchildren in Northern Sweden, the parents of 2612 (96% of invited) completed a questionnaire. All 125 (5%) children who reported complete elimination of milk, egg, fish or wheat due to food hypersensitivity were invited to a clinical examination and 94 children participated. Of these, 75 children also completed a generic (KIDSCREEN-52) and a disease-specific HRQL questionnaire (FAQLQ-TF). Thereafter, these children were categorised into the different phenotypes: current food allergy, outgrown food allergy, and lactose intolerance. Additionally, 209 children with unrestricted diets answered the generic questionnaire. RESULTS: The median score of all KIDSCREEN-52 domains were above the population norm of 50 both in children with and without food hypersensitivity. No significant differences in distribution in generic or disease-specific HRQL were found between children with or without food hypersensitivity. There were no significant differences in HRQL between children with different phenotypes of food hypersensitivity. However, children with current food allergy tended to have the lowest HRQL. Further, poor HRQL defined as ≥75th percentile for the disease specific score was significantly more common in the current food allergy phenotype in the domain Emotional impact and the total FAQLQ, compared to the other phenotypes. CONCLUSIONS: In this population-based study, 12-13 year old children reported good HRQL regardless of having food hypersensitivity or not. However, the children with the current phenotype reported lower HRQL than the other phenotypes.

Dynamics of cytokine mRNA expression and fecal biomarkers in school-children undergoing a double-blind placebo-controlled food challenge series.

BACKGROUND: There is need for prognostic markers for symptomatic food allergy since current diagnostic methods are insufficient and/or time and labor consuming. OBJECTIVE: To estimate the cytokine mRNA profiles in peripheral blood mononuclear cells (PBMC) before and after a double-blind placebo-controlled food challenge series in schoolchildren with suspected allergy to milk, egg or cod and in healthy controls. Analyses of fecal inflammatory biomarkers before and after the challenge were included. METHODS: Twelve-year-old children from a population-based cohort reporting complete avoidance of milk, egg, cod or wheat due to perceived hypersensitivity were clinically examined and those with suspected food allergy were evaluated with a 3-session double-blind placebo-controlled food challenge (n=18). Seven healthy controls participated in a double-blind challenge with egg. Before and after the challenge series, the cytokine mRNA expression was quantified for 13 cytokines discriminating between humoral Th2-, cytotoxic Th1-, regulatory Th3/Tr1- and inflammatory responses. Fecal calprotectin and eosinophil-derived neurotoxin (EDN) were also analyzed in children with suspected food allergy before and after the challenge series. RESULTS: Pre challenge, children with suspected food allergy had higher IL-13andTNF-α expression and lower IFN-γ and IL-15 expression compared to healthy controls (all p<0.05). Children with challenge-proven food allergy had increased IL13andIL-10 expression compared to the levels seen in negative challenges (p<0.05). Post challenge, IL-1ß and IL-6 mRNA levels were elevated in the food allergic children compared to controls (p<0.05). Fecal calprotectin and EDN levels were higher in challenge-proven food allergy compared to a negative challenge although not statistically significantly. CONCLUSION & CLINICAL RELEVANCE: Increased baseline mRNA levels of the Th2-related cytokine IL-13 and the regulatory cytokine IL-10 predicted a positive food challenge outcome. These cytokines in combination with fecal calprotectin and EDN might serve as future prognostic markers for symptomatic, IgE-mediated food allergy but need further validation in a larger patient cohort.

Milk allergy is a minor cause of milk avoidance due to perceived hypersensitivity among schoolchildren in Northern Sweden.

AIM: We investigated phenotypes of milk hypersensitivity among schoolchildren aged 11-12 in Northern Sweden. METHODS: In a population-based cohort, 1824 (98%) children aged 11-12 participated in a questionnaire survey, skin prick testing, interviews on food hypersensitivity and assessment of body mass index (BMI). Of the 265 children reporting milk hypersensitivity, milk avoidance and no coeliac disease, 236 (89%) participated in a structured interview and blood samples for analyses of milk-specific Immunoglobulin E. The children were then categorised into milk hypersensitivity phenotypes according to preset criteria. RESULTS: In all, 14.5% reported milk hypersensitivity. Of these, 3% were categorised as current milk allergy, 23% as outgrown milk allergy, 40% as probable lactose intolerance and 11% as nondefinable. Furthermore, 23% had discontinued their elimination diet. Milk allergy was associated with other atopic disorders and lower BMI, with an odds ratio of 0.82 and 95% confidence interval of 0.80-0.98. Only 2% had previously undergone an oral challenge. CONCLUSION: The most common symptom phenotypes among Swedish children aged 11-12 with self-reported milk hypersensitivity and milk avoidance were probable intolerance and outgrown milk allergy, while current milk allergy was uncommon. Children with milk allergy had a lower BMI and most lacked a challenge-proven diagnosis.

Assessment of Allergy to Milk, Egg, Cod, and Wheat in Swedish Schoolchildren: A Population Based Cohort Study.

OBJECTIVES: Knowledge about the prevalence of allergies to foods in childhood and adolescence is incomplete. The purpose of this study was to investigate the prevalence of allergies to milk, egg, cod, and wheat using reported data, clinical examinations, and double-blind placebo-controlled food challenges, and to describe the phenotypes of reported food hypersensitivity in a cohort of Swedish schoolchildren. METHODS: In a population-based cohort of 12-year-old children, the parents of 2612 (96% of invited) completed a questionnaire. Specific IgE antibodies to foods were analyzed in a random sample (n=695). Children reporting complete avoidance of milk, egg, cod, or wheat due to perceived hypersensitivity and without physician-diagnosed celiac disease were invited to undergo clinical examination that included specific IgE testing, a celiac screening test, and categorization into phenotypes of food hypersensitivity according to preset criteria. Children with possible food allergy were further evaluated with double-blind challenges. RESULTS: In this cohort, the prevalence of reported food allergy to milk, egg, cod, or wheat was 4.8%. Food allergy was diagnosed in 1.4% of the children after clinical evaluation and in 0.6% following double-blind placebo-controlled food challenge. After clinical examination, children who completely avoided one or more essential foods due to perceived food hypersensitivity were categorized with the following phenotypes: allergy (29%), outgrown allergy (19%), lactose intolerance (40%), and unclear (12%). CONCLUSIONS: There was a high discrepancy in the prevalence of allergy to milk, egg, cod and wheat as assessed by reported data, clinical evaluation, and double-blind food challenges. Food hypersensitivity phenotyping according to preset criteria was helpful for identifying children with food allergy.

A population-based study of animal component sensitization, asthma, and rhinitis in schoolchildren.

BACKGROUND: Animal sensitization is a major determinant of asthma in children. Component-resolved studies of unselected pediatric populations are lacking. The aim was to describe sensitization to animal components and the association with asthma and rhinitis in animal-sensitized schoolchildren. METHODS: A random sample of 696 children (11-12 years) from a Swedish population-based cohort was tested for sensitization to cat, dog, and horse dander using ImmunoCAP. Sera from animal-sensitized children were further analyzed by microarray including three allergen components from cat, four from dog, and two from horse. The parents completed an expanded ISAAC questionnaire. RESULTS: Of 259 animal-sensitized children (≥0.1 kUA /l), 51% were sensitized to all three, 23% to two, and 25% to one species. Current asthma and asthma symptoms following contact with cats were associated with co-sensitization to Fel d 1 and Fel d 4. This association was seen already at moderate-level sensitization (1-15 ISU) to Fel d 4, at which level most children were sensitized to Fel d 1, as well. In dog-sensitized children, the majority was sensitized to more than one dog component, and co-sensitization to Can f 5 and Can f 1/f 2 conferred the greatest risk for asthma. Sensitization to the highly cross-reactive serum albumins was uncommon and not associated with asthma. CONCLUSIONS: Among schoolchildren in northern Sweden, where mite allergy is uncommon, furry animals were the primary perennial sensitizers. Asthma was associated with higher levels of component sensitization, and sensitization to more than one component from the same animal conferred the greatest risk.

Food hypersensitivity is common in Swedish schoolchildren, especially oral reactions to fruit and gastrointestinal reactions to milk.

AIM: This study examined the prevalence, symptom expression and risk factors for food hypersensitivity among Swedish schoolchildren. METHODS: Parents of 2585 (96% of invited) children aged 7-8 years completed a questionnaire regarding food hypersensitivity and allergic diseases. A random sample of 1700 children (90% of invited) also participated in skin prick testing with ten airborne allergens. RESULTS: The overall prevalence of reported food hypersensitivity to milk, egg, fish, wheat, soya, fruits and, or, nuts was 21%, with symptoms caused by milk (9%) being the most common. The most frequently reported symptoms were oral symptoms (47.4%), mainly caused by fruit, and gastrointestinal symptoms (45.7%), mainly caused by milk. Factors associated with any food hypersensitivity were female sex, allergic heredity and a positive skin prick test. Eczema was consistently associated with symptoms caused by milk, egg, fish, wheat, soya, fruits and nuts. Rhinitis was associated to the same foods, except milk. CONCLUSION: Reported food hypersensitivity was common among Swedish schoolchildren. The most frequent symptom expressions were oral symptoms triggered by fruits and gastrointestinal symptoms triggered by milk. The high prevalence of reported symptoms should be validated by clinical examinations to provide a diagnosis.

High incidence and remission of reported food hypersensitivity in Swedish children followed from 8 to 12 years of age - a population based cohort study.

BACKGROUND: Few population-based cohort studies have examined reported food hypersensitivity longitudinally. We investigated prevalence, incidence and remission of perceived food hypersensitivity among schoolchildren from 8 to 12 years of age, and risk factors associated with incidence and remission. METHODS: A population-based cohort including all 7-8 year-old children in three Swedish towns was recruited in 2006. A total of 2,585 (96% of invited) children participated in a parental questionnaire. The children in two of the towns, n = 1,700 (90% of invited) also participated in skin-prick-testing with airborne allergens. The cohort was followed using the same methods at 11-12 years of age. At study follow up, specific IgE to foods was analyzed in a randomized subset of children (n = 652). RESULTS: The prevalence of perceived food hypersensitivity increased from 21% at 8 years to 26% at 12 years of age. During this four-year-period, the cumulative incidence of food hypersensitivity was high (15%), as was remission (33%). This pattern was particularly evident for hypersensitivity to cow´s milk, while the incidence of hypersensitivity to other foods was lower. Female sex, allergic heredity, current rhinitis and allergic sensitization were associated with the incidence of food hypersensitivity and allergic sensitization was negatively associated with remission. Risk-factor-patterns for both incidence and remission were different for hypersensitivity to milk compared with hypersensitivity to other foods. Generally, the agreement between reported food hypersensitivity and IgE-sensitization to the implicated food was poor. CONCLUSIONS: In this longitudinal, population-based cohort-study perceived food hypersensitivity was common among children between ages 8 and 12, often transient and not well correlated with food-specific IgE. While these findings suggest an overestimated prevalence of food hypersensitivity, the public-health-significance remains high as they reflect the perceived reality to which the children adapt their life and food intakes.

New validated recipes for double-blind placebo-controlled low-dose food challenges.

Double-blind placebo-controlled food challenges are considered the most reliable method to diagnose or rule out food allergy. Despite this, there are few validated challenge recipes available. The present study aimed to validate new recipes for low-dose double-blind placebo-controlled food challenges in school children, by investigating whether there were any sensory differences between the active materials containing cow's milk, hen's egg, soy, wheat or cod, and the placebo materials. The challenge materials contained the same hypoallergenic amino acid-based product, with or without added food allergens. The test panels consisted of 275 school children, aged 8-10 and 14-15 yr, respectively, from five Swedish schools. Each participant tested at least one recipe. Standardized blinded triangle tests were performed to investigate whether any sensory differences could be detected between the active and placebo materials. In our final recipes, no significant differences could be detected between the active and placebo materials for any challenge food (p > 0.05). These results remained after stratification for age and gender. The taste of challenge materials was acceptable, and no unfavourable side effects related to test materials were observed. In summary, these new validated recipes for low-dose double-blinded food challenges contain common allergenic foods in childhood; cow's milk, hen's egg, soy, wheat and cod. All test materials contain the same liquid vehicle, which facilitates preparation and dosing. Our validated recipes increase the range of available recipes, and as they are easily prepared and dosed, they may facilitate the use of double-blind placebo-controlled food challenges in daily clinical practice.

Vitamin D deficiency at the Arctic Circle - a study in food-allergic adolescents and controls.

AIM: At the extremes of latitude, UVB intensity is insufficient for adequate vitamin D synthesis in winter. Fatty fish, vitamin D enriched milk, margarine and eggs are main dietary sources of vitamin D. Their elimination may increase the risk of vitamin D deficiency. The aim was to assess vitamin D status in food-allergic adolescents eliminating milk, egg and/or fish compared with adolescents on normal diets. METHODS: In winter, vitamin D intake was assessed by a food frequency questionnaire in 20 food-allergic adolescents and 42 controls in the population-based Obstructive Lung Disease In Northern Sweden (OLIN) cohort studies. Vitamin D supplementation was queried. Serum 25-hydroxyvitamin D [S-25(OH)D] and S-parathormone (S-PTH) levels were determined. RESULTS: Mean (SD) dietary vitamin D intake was 7.9 (3.6) µg/day in allergic adolescents and 7.8 (3.4) in controls (p > 0.05). Mean (SD) S-25(OH)D levels in supplement consumers were 44 (18) nmol/L compared with 35 (10) in non-consumers (p = 0.03). S-25(OH)D and S-PTH levels were similar in food-allergic adolescents and controls (p > 0.05). Eighty-two percentage had deficient S-25(OH)D levels <50 nmol/L, and none reached levels >75 nmol/L. CONCLUSION: Vitamin D deficiency was as common in food-allergic adolescents as in controls although the vitamin D intake met national recommendations. Large-scale studies on the prevalence of vitamin D deficiency in this region are needed.