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A Nationwide Study of Asthma and Allergy in Swedish Preschool Children: with Special Reference to Environment, Daycare, Prevalence, Co-ocurrence and Incidence
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Family Medicine and Clinical Epidemiology.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aim: The aim of this project was to study the age and sex specific occurrence of atopic and non-atopic asthma and other atopic manifestations in a nationwide sample of Swedish pre-school children.

Methods: All 70 allergen avoidance day-care centres (AADC) with 84 sections and 140 matched ordinary day-care centres with 440 sections in 62 municipalities across Sweden were sampled. In 2000 the staff at each section responded to a questionnaire on indoor and outdoor environment at the section. In 2002 parents of 5,886 children attending the AADCs and ODCs responded to a postal questionnaire regarding symptoms indicating prevalent asthma, allergic rhinitis, eczema, and food, furred pet and pollen allergy and other data in their children. In 2007, parents of 4255 children responded to an almost identical follow-up questionnaire.

Results: The AADCs had far more strict rules than ODCs on furred pets and smoking at home and on perfume use, and the indoor environment was better, owing to better cleaning. The age specific asthma prevalence was curvilinear with a peak at age 3 of 11.4% among boys and 9.8% among girls. In addition the prevalence increased by municipality population density, a proxy for degree of urbanisation. There was a highly significant co-occurrence between all asthma-atopic manifestations, but there was no evidence of ordered sequence of manifestation onset. The asthma incidence was highly dependent on presence or absence of co-occurrence variables. Given the variable mix in the present study population, the annual asthma incidence ranged from 0.6% to 1.2%.

Conclusions: AADCs had more strict rules and a better indoor environment than ODCs. The asthma prevalence was affected by age, sex and degree of urbanisation. There was close co-occurrence between all asthma and atopic manifestations but no evidence of ordered sequence of onsets. The annual asthma incidence was strongly dependent of co-occurrence conditions.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2010. , p. 69
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 542
Keywords [en]
Asthma, rhinitis, eczema, allergy, indoor environment, daycare centre, prevalence, incidence epidemiology
National Category
General Practice
Research subject
Family Medicine
Identifiers
URN: urn:nbn:se:uu:diva-121426ISBN: 978-91-554-7759-2 (print)OAI: oai:DiVA.org:uu-121426DiVA, id: diva2:305286
Public defence
2010-05-07, Brömssalen, ingång 11, Länssjukhuset, Gävle, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2010-04-16 Created: 2010-03-23 Last updated: 2018-01-12
List of papers
1. A nationwide study of indoor and outdoor environments in allergen avoidance and conventional daycare centers in Sweden
Open this publication in new window or tab >>A nationwide study of indoor and outdoor environments in allergen avoidance and conventional daycare centers in Sweden
2006 (English)In: Indoor Air, ISSN 0905-6947, E-ISSN 1600-0668, Vol. 16, no 3, p. 227-35Article in journal (Refereed) Published
Abstract [en]

Sweden has had specialized 'allergen avoidance daycare centers' (AADC) since 1979. The aim was to compare AADC with ordinary daycare centers (ODC). Through contacts with municipalities and hospitals, 72 AADC were identified. For each AADC, the two nearest ODCs served as controls. A questionnaire was sent to the local directors of the 216 daycare centers (531 sections), 83% responded. A total of 39% of the ODCs had ever had dampness/molds, 12% were near (<500 m) stables/farms, 23% were closer than 50 m to a heavy trafficked road, and 13% were exposed to wood smoke in winter. Only 11% of the AADCs had any child with furred pets at home, while 97% of the ODCs had children with furred pets. Bans on smoking at home and on perfumes were more common at the AADCs (P = 0.001). Fewer AADCs had PVC floors (OR = 0.53; P = 0.01), dampness/molds (OR = 0.55; P = 0.04), shelves (OR 3.03; P = 0.001), curtains (OR = 1.67; P = 0.047), and flowers (OR = 0.03; P < 0.001), while more had daily floor cleaning (OR = 19.9; P = 0.004), weekly wiping of furniture (OR = 11.0; P = 0.001), and washing of pillows/mattresses (OR = 2.74; P = 0.005) and curtains (OR = 9.07; P = 0.001). In conclusion, allergy avoidance daycare centers differ from other daycare centers, and may have better indoor environments. PRACTICAL IMPLICATIONS: There is a need to improve the indoor environments of daycare centers, including reduction of building dampness and molds. Allergen avoidance daycare centers (AADC) in Sweden differ from ordinary daycare centers in many respects, with fewer indoor and building factors related to dust, allergens and irritants. This shows that the indoor environments of daycare centers can be improved. Data suggest that AADC may have lower levels of pet allergens, and this is beneficial for children with pet allergy. The effects of these improvements on indoor exposures and health of the children need to be further evaluated.

Keywords
Air Pollutants, Air Pollution; Indoor/*analysis, Allergens/*analysis, Animals, Antigens; Dermatophagoides/analysis, Cats, Child Day Care Centers, Child; Preschool, Cockroaches, Dogs, Dust/analysis, Environmental Monitoring, Facility Design and Construction, Humans, Questionnaires, Sick Building Syndrome, Sweden, Ventilation
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-81290 (URN)10.1111/j.1600-0668.2005.00420.x (DOI)16683941 (PubMedID)
Available from: 2008-06-25 Created: 2008-06-25 Last updated: 2017-12-14Bibliographically approved
2. Effect of degree of urbanisation on age and sex-specific asthmaprevalence in Swedish preschool children
Open this publication in new window or tab >>Effect of degree of urbanisation on age and sex-specific asthmaprevalence in Swedish preschool children
Show others...
2009 (English)In: BMC Public Health, ISSN 1471-2458, E-ISSN 1471-2458, Vol. 9, p. 303-Article in journal (Refereed) Published
Abstract [en]

Background: There are few studies on age and sex-specific asthma   prevalence in the age range 1-6 years. The purpose of this report was   to estimate age and sex specific asthma prevalence in preschool   children and to analyse the influence of possible demographic and   geographic determinants.   Methods: All 70 allergen avoidance day-care centres and 140 matched   ordinary day-care centres across Sweden were sampled. The parents of   all 8,757 children attending these day-care centres received the   International Study of Asthma and Allergies in Childhood (ISAAC)   written questionnaire, supplemented with questions on medical   treatment, physician assessed asthma diagnosis, and other asthma   related questions. The response rate was 68%.   Results: The age specific asthma prevalence, adjusted for the   underlying municipality population size, was among boys 9.7% at age 1,   11.1% at age 2, 11.4 at age 3, 10.5 at age 4, 8.7 at age 5, and 6.4 at   age 6. The corresponding proportions among girls were 8.9%, 9.9%, 9.8%,   8.8%, 7.0%, and 5.0%, on average 9.6% for boys and 8.2% for girls,   altogether 8.9%. In addition to age and sex the prevalence increased by   municipality population density, a proxy for degree of urbanisation.   Moreover, there was a remaining weak geographical gradient with   increasing prevalence towards the north and the west.   Conclusion: The age-specific asthma prevalence was curvilinear with a   peak around age 3 and somewhat higher for boys than for girls. The   asthma prevalence increased in a slowly accelerating pace by   municipality population density as a proxy for degree of urbanisation.

National Category
Medical and Health Sciences
Research subject
Family Medicine
Identifiers
urn:nbn:se:uu:diva-120578 (URN)10.1186/1471-2458-9-303 (DOI)000270673700001 ()19695101 (PubMedID)
Available from: 2010-03-15 Created: 2010-03-15 Last updated: 2017-12-12Bibliographically approved
3. Prevalence and co-occurrence of asthma and allergic manifestations in preschool children
Open this publication in new window or tab >>Prevalence and co-occurrence of asthma and allergic manifestations in preschool children
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: It has been claimed that preschool children may embark on ‘the atopic march’, which means that atopic manifestations show up one after another in a certain order. The aim of this study was to make an in-depth analysis of the co-occurrence of asthma and atopic manifestations.

Methods: Parents of 5886 children 1-6 years of age, sampled from day-care centres in 62 municipalities all over Sweden, responded to a postal questionnaire regarding symptoms indicating prevalent asthma, allergic rhinitis, eczema, food allergy, furred pet and pollen allergy and other data in their children. Age specific prevalence of asthma, rhinitis, eczema, and food allergy was computed, adjusted for municipality population size.

Results: The overall prevalence of asthma was 8.9%, of eczema 21.7%, of rhinitis 8.1%, and of food allergy 6.6%. There was a highly significant co-occurrence between all asthma-atopic manifestations. Presence of pet allergy was the manifestation showing the closest co-occurrence with presence of asthma, presence of pollen allergy with presence of rhinitis, and presence of food allergy with presence of eczema. Assessed from plots of age specific prevalence of asthma, rhinitis, eczema and food allergy the prevalence of all manifestations increased from one to three years of age and then decreased, except for rhinitis where the prevalence increased until six years of age. There was no evidence of a rank order of asthma and allergy manifestation onset.

Conclusions: There was close co-occurrence between all asthma-atopic manifestations but no evidence of a rank order of onsets.

Keywords
asthma, rhinitis, eczema, food allergy, epidemiology
National Category
General Practice
Research subject
Family Medicine
Identifiers
urn:nbn:se:uu:diva-120585 (URN)
Available from: 2010-03-15 Created: 2010-03-15 Last updated: 2018-01-12
4. A nationwide study of asthma incidence and its determinants in preschool children during five years of follow up
Open this publication in new window or tab >>A nationwide study of asthma incidence and its determinants in preschool children during five years of follow up
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: Many studies on asthma prevalence have been published, but the number of studies on asthma incidence in preschool children is limited.

A number of studies on asthma prevalence have been published, but there are few studies on asthma incidence in preschool children. In this project a nationwide sample of preschool children were followed with the aim to estimate 5-year asthma incidence and its determinants.

Methods: Parents of 5886 children 1-6 years of age, sampled from day-care centres in 62 municipalities all over Sweden, responded in 2002 to a baseline postal questionnaire with questions regarding symptoms indicating possible asthma or atopic conditions, and a number of other variables. In 2007, 4255 of the parents responded to an almost identical questionnaire.

Results: A large number of potential baseline determinants for 5-year asthma incidence were identified. Of these, food allergy, wheezing last 12 months, rhinitis, parental rhinitis, parental asthma, ever asthma, age, and eczema, on rank order of importance, remained significant in multivariate logistic regression analysis. The asthma incidence was highly dependent on presence or absence of these variables. Given the variable mix in the present study population, the incidence ranged from 2.9% in the oldest to 5.8% in the youngest children, corresponding to an annual asthma incidence of 0.6% to 1.2%.

Conclusions: The incidence of asthma is highly dependent on the composition of the underlying population. However, an annual incidence in range a half to one percent in preschool children in the general population appears probable.

Keywords
asthma, incidence rate, preschool children, determinants, parental atopy
National Category
General Practice
Research subject
Family Medicine
Identifiers
urn:nbn:se:uu:diva-120591 (URN)
Available from: 2010-03-15 Created: 2010-03-15 Last updated: 2018-01-12

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