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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.

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 reexamined 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.

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.

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.

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.

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.

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.

Aim: International reports have suggested that food allergies and food‐induced anaphylaxis have increased in children. We investigated the incidence of emergency food reactions over a 10‐year period.

Methods: This study retrospectively reviewed the medical records of children presenting to Umeå University hospital, Sweden, with an emergency food reaction from January 1, 2006 to December 31, 2015. Cases were identified using discharge codes for allergies and anaphylaxis. Anaphylaxis cases were included if they fulfilled the international criteria.

Results: We found emergency food allergy reactions in 519 children (58% boys) from 2006–2015 at a median age of 1.3 years. One‐third were hospitalised (32%) including 71/99 cases of anaphylaxis. Milk and eggs were the most commonly identified triggers. Emergency reactions to eggs increased during the study period with a Spearman rank correlation coefficient of 0.770 (p < 0.01) and the figures for anaphylaxis were 0.745 (p = 0.013). The incidence of food‐induced anaphylaxis increased and was 30 per 100 000 person‐years for the study period.

Conclusion: Most of the emergency reactions, treated by secondary care paediatricians and emergency physicians, were to milk and eggs. Allergic reactions to eggs increased from 2006 to 2015, as did food‐related anaphylaxis.

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 61/2-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 kPaL(-1)s(-1)) and larger area under the reactance curve (AX, 0.78, 95%CI: 0.49; 1.07kPaL(-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.