The Obstructive Lung Disease in Northern Sweden (OLIN) longitudinal paediatric study I--the first 10 years

Asthma in adolescence affects daily life and school attendance - Two cross-sectional population-based studies 10 years apart

Aim

The aim of this study was to study the impact of asthma on daily life, school absenteeism and physical education. In addition, to describe asthma triggers at school.

Design

Two cross‐sectional population‐based studies ten years apart.

Method

Within the OLIN‐studies, in 2003 (n = 3,327) and in 2013 (n = 2,345) adolescents (14–15 years) answered an expanded ISAAC questionnaire. Of these, 8% and 11%, respectively with current asthma participated in this study.

Results

Between the years 2003–2013, the proportion of adolescents reporting that asthma interfered with daily life had increased, in 2013, girls were significantly more affected than boys. The proportion reporting a worsening of asthma at school had decreased, but it was still over a quarter. The proportion of absenteeism from school and from physical education was at the same level both years. Asthma triggers were described to be poor air quality, poorly cleaned environment, allergens, strong fragrance, rebuilding projects, physical education and stress.

Asthma phenotypes in childhood

INTRODUCTION

Asthma is no longer thought of as a single disease, but rather a collection of varying symptoms expressing different disease patterns. One of the ongoing challenges is understanding the underlying pathophysiological mechanisms that may be responsible for the varying responses to treatment. Areas Covered: This review provides an overview of our current understanding of the asthma phenotype concept in childhood and describes key findings from both conventional and data-driven methods. Expert Commentary: With the vast amounts of data generated from cohorts, there is hope that we can elucidate distinct pathophysiological mechanisms, or endotypes. In return, this would lead to better patient stratification and disease management, thereby providing true personalised medicine.

Environmental risk factors related to the incidence of wheeze and asthma in adolescence

BACKGROUND

Asthma is common among adolescents, but there are few population-based studies on the risk factors for incident asthma and wheeze at this age group.

OBJECTIVE

To study risk factors for incident asthma and wheeze in adolescence.

METHOD

Within the Obstructive Lung Disease In Northern Sweden (OLIN) studies, a cohort of 3430 school children (age 7-8 year) was recruited in 1996. In the present study, this cohort was followed from age 12-19 year. At baseline (age 12 year), 3151 participated and skin prick tests (SPT) were performed. The cohort was resurveyed annually, and risk factors for the cumulative incidence of asthma and wheeze from age 12-19 year were analysed using multivariate Cox regression.

RESULTS

Female sex (wheeze: HR 1.4 95%CI 1.2-1.6; asthma: HR 1.8 95%CI 1.2-2.5) and a positive SPT to cat, dog or horse at baseline (wheeze: HR 1.6 95%CI 1.2-2.1; asthma: HR 2.3 95%CI 1.4-4.0) were significantly associated with the cumulative incidence of wheeze and asthma. Increasing numbers of siblings were inversely related to the incidence of wheeze (HR 0.9 95%CI 0.8-0.97) and asthma (HR 0.8 95%CI 0.7-0.97). Parental asthma was related to the incidence of asthma (HR 1.8 95%CI 1.2-2.6) while ever smoking (HR 2.0 95%CI 1.6-2.4) and house dampness (HR 1.3 95%CI 1.1-1.6) were risk factors for the incidence of wheeze. Maternal ETS exposure increased the risk of incident asthma in non-sensitized subjects (HR 1.9 95%CI 1.0-3.7).

CONCLUSION AND CLINICAL RELEVANCE

Several environmental risk factors related to the incidence of asthma and wheeze in adolescence were identified and may be possible targets for intervention and prevention.

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.

The natural course of sensitization and allergic diseases from childhood to adulthood

BACKGROUND

Longitudinal prospective population-based birth cohort studies of the natural history of sensitization and allergic diseases from childhood to adulthood are few. The aim of the present prospective study was to investigate the natural course of sensitization and allergic diseases in a random population-based sample of 276 children from a 1-year birth cohort of unselected Danish children followed from birth to 26 years of age.

METHODS

Questionnaire-based interviews, physical examination, skin prick tests, specific IgE testing, and from 10 years also spirometry, were carried out at 1.5, 5, 10, 15 and 26 years of age. Predefined diagnostic criteria were used.

RESULTS

Follow-up rates were high, 193 (70%) attended the 26-year follow-up. The prevalence of current eczema was stable during childhood; 13% (1.5 yrs.), 9.2% (5 yrs.), 10.8% (10 yrs.), and 9.8% (15 yrs.), and 5.7% at 26 yrs. From birth to 26 years the cumulative prevalence of eczema, food allergy, asthma, and rhinoconjunctivitis was 23.5%, 13.8%, 17%, and 27.9% respectively. More than half of the participants had one or more allergic disease in the period between birth and 26 years of age. The rates of sensitization (S-IgE = 0.35 kU/l) were 8%, 23%, 26%, 32%, and 31% at 1.5, 5, 10, 15, and 26 years of age, respectively. Sensitization to food allergens was most prevalent in early infancy, whereas sensitization to inhalant allergens dominated later on.

CONCLUSION

The results support the concept of the allergic march. Allergic diseases are not only occurring in childhood but persist into adulthood.

Conventional epidemiology underestimates the incidence of asthma and wheeze-a longitudinal population-based study among teenagers

Background

Because of shifts in the gender ratio and incidence and remission rates of asthma during the teen ages, the methodology of incidence studies among teenagers is important, i.e. if the time intervals between surveys are too long, the incident cases might not be properly identified. The aim was to study the impact of study design on the incidence rates of asthma and wheeze during the teen ages.

Methods

In a study about asthma and allergic diseases within the OLIN studies (Obstructive Lung Disease in northern Sweden), a cohort of school children (n = 3,430) was followed annually by questionnaire from age 8 yrs. In the endpoint survey (age 18 yrs) 2,582 (75% of original responders) participated. Incident cases from age 12-18 yrs were identified by two methods: annual questionnaire reports (AR) and baseline-endpoint surveys only (BE).

Results

The cumulative incidence of asthma and wheeze was significantly higher based on AR compared to BE. Compared to the incidence rates based on all the annual surveys, the calculated average annual rates based on BE were in general lower both among the boys and among the girls. There were no differences between boys and girls in incidence rates of asthma or wheeze during the early teen years. However, from the age of 15 years, the annual incidence rates were significantly or borderline significantly higher among girls than boys. At onset, the additional cases of current asthma identified by AR had significantly less severe asthma than those identified in BE (p < 0.02).

Conclusion

the size of the incidence of asthma and wheeze during the teen ages was influenced by study design. By using the conventional prospective study design with longer follow-up time, the incidence was underestimated.

The clinical expression of asthma in schoolchildren has changed between 1996 and 2006

Several studies have reported diverging trends in the prevalence of asthma and wheeze. The aim of this study was to investigate the clinical expression of childhood asthma in 1996 and 2006 by studying asthma morbidity, treatment, and environmental exposures in school children with physician-diagnosed asthma and wheeze, respectively. All children enrolled in first or second grade (7-8 yr-old) in three municipalities in northern Sweden were invited to a questionnaire study in 1996 and 2006, respectively. In 1996, 3430 (97%) participated; and in 2006, 2585 (96%) participated. The same parental completed questionnaire, including the ISAAC questions, was used in both surveys. Physician-diagnosed asthma was reported at 5.7% in 1996 and 7.4% in 2006. A significantly greater proportion of children with asthma were using inhaled corticosteroids (ICS) in 2006, 67% vs. 55% in 1996. This increase was parallel to a major decrease in severe asthma symptoms such as disturbed sleep because of wheeze (49% vs. 38%) and troublesome asthma (21% vs. 11%). The prevalence of current wheeze among the asthmatics decreased significantly; however, this was seen only among children not using ICS. Parental smoking decreased significantly as did the proportion living in damp buildings. In conclusion, although asthma remains a major public health issue in school age children, children with asthma had less respiratory symptoms and a better asthma control in 2006 compared to 1996. This parallels with an increase in treatment with ICS, more beneficial environmental conditions, and an increased diagnostic intensity resulting in a larger proportion of children with mild symptoms being diagnosed as having asthma.