Grandmaternal smoking increases asthma risk in grandchildren: A nationwide Swedish cohort

BACKGROUND

There is growing interest in exposures prior to conception as possible risk factors for offspring asthma. Although partially supported by evidence from limited human studies, current evidence is inconsistent and based on recall of exposure status.

OBJECTIVE

We aimed to investigate grandmaternal smoking during pregnancy and the risk of asthma in grandchildren using prospectively collected population-based data.

METHODS

Information on grandmaternal and maternal smoking during pregnancy and grandchild use of asthma medications was collected from national Swedish registries. Associations between grandmaternal smoking during pregnancy (10-12 weeks) and asthma medication use in grandchildren were investigated using generalized estimating equations. Ages at which asthma medications were prescribed classified childhood asthma into never, early transient (0-3 years), late onset (3-6 years) and early persistent (0-3 and 3-6 years) phenotypes.

RESULTS

From 1982 to 1986, 44 583 grandmothers gave birth to 46 197 mothers, who gave birth to 66 271 grandchildren (born 1996-2010). Children aged 1-6 years had an increased asthma risk if their grandmothers had smoked during pregnancy, with a higher risk for more exposure (10+ cigs/d; adjusted OR 1.23; 1.17, 1.30). Maternal smoking did not modify this relationship.

CONCLUSIONS & CLINICAL RELEVANCE

Children had an increased risk of asthma in the first 6 years of life if their grandmothers smoked during early pregnancy, independent of maternal smoking. Importantly, this exhibited a dose-response relationship and was associated with a persistent childhood asthma phenotype. These findings support possible epigenetic transmission of risk from environmental exposures in previous generations.

International variations in associations of allergic markers and diseases in children: ISAAC Phase Two

BACKGROUND

Circulating allergen-specific IgE (sIgE) and skin prick tests (SPT) are used to define atopy. Downregulation of local inflammatory responsiveness has been proposed to explain a low prevalence of positive SPTs in less affluent countries. We analysed the association between SPTs, total and allergen-specific IgE and their relationships to allergic symptoms in centres with diverse living conditions.

METHODS

Cross-sectional studies of stratified random samples of 8 to 12-year-old children (n = 7461) used the standardized methodology of Phase Two of the International Study of Asthma and Allergies in Childhood (ISAAC). Symptoms of asthma, rhinitis and eczema were ascertained by parental questionnaires. Skin examination, hypertonic saline bronchial challenge, six aeroallergen SPTs and measurements of serum total IgE and sIgE were performed.

RESULTS

In nonaffluent countries, a higher proportion of children with positive SPT had no detectable sIgE (range 37-61%) than in affluent countries (0-37%). Total serum IgE was associated with all disease outcomes among children with both positive SPT and sIgE (P < 0.001), but only with self-reported eczema in children with negative SPTs and negative sIgE.

CONCLUSIONS

The international pattern of discordance between SPT and sIgE results did not support the downregulation hypothesis. Among children with no evidence of sensitization to common aeroallergens, increased total IgE contributes little to the risk of wheeze and rhinitis in the general population but may play a role in eczema.

A multi-centre study of candidate genes for wheeze and allergy: the International Study of Asthma and Allergies in Childhood Phase 2

BACKGROUND

Common polymorphisms have been identified in genes suspected to play a role in asthma. We investigated their associations with wheeze and allergy in a case-control sample from Phase 2 of the International Study of Asthma and Allergies in Childhood.

METHODS

We compared 1105 wheezing and 3137 non-wheezing children aged 8-12 years from 17 study centres in 13 countries. Genotyping of 55 candidate single nucleotide polymorphisms (SNPs) in 14 genes was performed using the Sequenom System. Logistic regression models were fitted separately for each centre and each SNP. A combined per allele odds ratio and measures of heterogeneity between centres were derived by random effects meta-analysis.

RESULTS

Significant associations with wheeze in the past year were detected in only four genes (IL4R, TLR4, MS4A2, TLR9, P<0.05), with per allele odds ratios generally <1.3. Variants in IL4R and TLR4 were also related to allergen-specific IgE, while polymorphisms in FCER1B (MS4A2) and TLR9 were not. There were also highly significant associations (P<0.001) between SPINK5 variants and visible eczema (but not IgE levels) and between IL13 variants and total IgE. Heterogeneity of effects across centres was rare, despite differences in allele frequencies.

CONCLUSIONS

Despite the biological plausibility of IgE-related mechanisms in asthma, very few of the tested candidates showed evidence of association with both wheeze and increased IgE levels. We were unable to confirm associations of the positional candidates DPP10 and PHF11 with wheeze, although our study had ample power to detect the expected associations of IL13 variants with IgE and SPINK5 variants with eczema.

How well do questionnaires perform compared with physical examination in detecting flexural eczema? Findings from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two

BACKGROUND

Questionnaires are widely used in epidemiological studies to measure eczema symptom prevalence, but there are concerns regarding their accuracy if used as a diagnostic tool.

OBJECTIVES

To compare the performance of a validated eczema symptom questionnaire and a standardized skin examination protocol employed in the second phase of the International Study of Asthma and Allergies in Childhood (ISAAC).

METHODS

A total of 30,358 schoolchildren aged 8-12 years from 18 countries were examined for flexural eczema. Parents also completed an eczema symptom questionnaire. We compared prevalence estimates at the population level based on the questionnaire vs. physical examination. We also compared the skin examination and the ISAAC questionnaire in making a diagnosis of flexural eczema.

RESULTS

The point prevalences for flexural eczema at centre level based on a single examination were lower than the questionnaire-based 12-month period prevalences (mean centre prevalence 3.9% vs. 9.4%). Correlation between prevalences of both outcome measures was high (r = 0.77, P < 0.001). At the individual level, questionnaire-derived symptoms of 'persistent flexural eczema in the past 12 months' missed < 10% of cases of flexural eczema detected on physical examination. However, between 33% and 100% of questionnaire-based symptoms of 'persistent flexural eczema in the past 12 months' were not confirmed on examination.

CONCLUSIONS

ISAAC questionnaire-derived symptom prevalences are sufficiently precise for comparisons between populations. Where diagnostic precision at the individual level is important, questionnaires should be validated and potentially modified in those populations beforehand, or a standardized skin examination protocol should be used.

Effect of breastfeeding on asthma, lung function and bronchial hyperreactivity in ISAAC Phase II

The association between breastfeeding and wheezing, lung function and atopy was evaluated in the International Study of Asthma and Allergy in Childhood (ISAAC) Phase II. Cross-sectional studies were performed in 27 centres in 20 countries. Information on disease and exposure factors was collected by parental questionnaires. Data from 54,000 randomly selected school children (aged 8-12 yrs, 31,759 with skin prick testing) and a stratified subsample (n = 4,888) were used for testing the correlation of breastfeeding with bronchial hyperreactivity and lung function. Random effect models for meta-analysis were applied to calculate combined odds ratios (ORs). Any breastfeeding was associated with less wheeze both in affluent (adjusted OR (OR(adj)) 0.87, 95% confidence interval (CI) 0.78-0.97) and nonaffluent countries (OR(adj) 0.80, 95% CI 0.68-0.94). Further analyses revealed that this was true only for nonatopic wheeze in nonaffluent countries (OR(adj) 0.69, 95% CI 0.53-0.90). Breastfeeding was not associated with atopic wheeze and objective measures of allergy in both affluent and nonaffluent countries. In contrast, breastfeeding was associated with higher predicted forced expiratory volume in one second in affluent countries only (mean ratio 1.11, 95% CI 1.02-1.20). Breastfeeding is associated with protection against nonatopic wheeze, which becomes particularly evident in nonaffluent countries. Overall, breastfeeding was not related to any measure of allergy. These findings may explain some of the controversy regarding breastfeeding, since the direction of the association with breastfeeding depends on the predominating wheeze phenotype (e.g. atopic, nonatopic).

Immunoglobulin constant heavy G chain genes as risk factors in childhood allergies

BACKGROUND

Several candidate genes have been found to be associated with the inflammatory response of IgE-mediated allergy, so also the immunoglobulin constant heavy G chain (IGHG) genes. The IGHG genes are situated close to the IGHE gene on chromosome 14q32, 5'mu, delta, gamma3, gamma1, alpha1, gamma2, gamma4, epsilon, alpha2, 3'. They are inherited in a Mendelian fashion and expressed randomly in allelic exclusion. The alternative and functionally different gamma3, gamma1 and gamma2 gene variants are found in four IGHG haplotypes, coding four B cell variants.

OBJECTIVE

The aim of this study was to assess the frequency of different IGHG genes in relation to phenotypes associated with allergy, in a case-control study.

METHODS

We identified the constant heavy-chain genes of IgG in 198 allergic and non-allergic children participating in the Phase II of the International Study of Asthma and Allergy in Children. The IGHG genes were assessed by the alternative serum IgG subclass allotypes expressing the alternative alleles of gamma3, gamma1 and gamma2 genes, using ELISA and double immunodiffusion.

RESULTS

The IGHG*bfn haplotype (=B1 cells) and IGHG2*n allele dominated (51% vs. 24%, P=0.002) and the IGHG*bf-n haplotype (=B2 cells) was infrequent (16% vs. 52%, P < 0.001) in allergic children with a family history of allergy, clinical manifest allergy and positive skin prick test (SPT). The frequency of IGHG genes was similar in children with maternal and paternal heredity and in children with wheezing, eczema or rhinitis, as well as in children with different positive SPT. The IGHG*bfn haplotype with the IGHG2*n allele was strongly associated with heredity for allergy. The IGHG*bf-n haplotype was inversely related to allergy. Conclusions IgG allotypes, immunochemical and functional variants of IgG molecules from IGHG genes are associated with atopy. The IGHG*bfn haplotype (=B1 cells) with the IGHG2*n allele dominates, associated with an increased risk for atopy. In contrast, the IGHG*bf-n haplotype (=B2 cells) with the IGHG2*-n allele is associated with low risk.

Psoriasis in Swedish conscripts: time trend and association with T-helper 2-mediated disorders

BACKGROUND

According to the T-helper (Th)1/Th2 paradigm, it has been argued that Th1-dominated diseases such as psoriasis and Th2-dominated diseases such as asthma and hay fever should be mutually exclusive, as the immune regulatory cells, Th1 and Th2, cross-regulate each other. An increase in asthma and hay fever has occurred in Sweden over the past four to five decades, but the time trend for psoriasis is not clear.

OBJECTIVES

To assess the prevalence of psoriasis in young Swedish men over a period of three decades and the association between psoriasis and allergic disorders.

METHODS

Register study based on data from the Swedish Military Service Conscription Register and the Total Population and the Population and Housing Censuses. Psoriasis, asthma (with and without allergic rhinitis) and allergic rhinitis at conscription were studied in 1 226 193 male conscripts in successive cohorts born between 1952 and 1977.

RESULTS

The prevalence of psoriasis was about 0.5% and it remained stable over three decades. Conscripts with psoriasis and their siblings were less likely to have eczema. The reduced risk of eczema in conscripts with psoriasis was unchanged over time. A reduced risk of allergic rhinitis was also demonstrated in conscripts with psoriasis and their siblings but only in the most recent birth cohort born between 1970 and 1977.

CONCLUSIONS

A strong genetic influence may explain the unchanged prevalence of psoriasis in Swedish conscripts. A genetic predisposition for psoriasis may confer partial protection from eczema and allergic rhinitis. The inverse relationship between allergic rhinitis and psoriasis appeared to be a recent phenomenon.

Social class in asthma and allergic rhinitis: a national cohort study over three decades

The aim of this study was to assess whether the association with social class differed between allergic rhinitis and asthma and whether these associations have changed over time. The Swedish Military Service Conscription Register was linked to two other national registers for 1,247,038 male conscripts in successive cohorts born between 1952 and 1977. The percentage of asthma cases associated with allergic rhinitis was 15% in the oldest cohort and 44% in the youngest cohort. Low socio-economic status (SES) was associated with an increased risk (assessed as odds ratio) of asthma without allergic rhinitis (1.14, 95% confidence interval (CI) 1.11-1.17) but a slightly reduced risk of asthma with allergic rhinitis (0.96, 95% CI 0.93-1.00). The risk of allergic rhinitis was 0.84, 95% CI 0.82-0.85. A positive interaction between SES and year of birth occurred in all three conditions. Low SES was related to a reduced risk of asthma with allergic rhinitis in the earliest cohort (0.72, 95% CI 0.53-0.82) but a slightly increased risk in the most recent cohort (1.07, 95% CI 1.01-1.14). In conclusion, the role of social class has changed over time. The steepest increase in asthma and allergic rhinitis occurred in conscripts with a low socio-economic status.

Prevalence of self-reported food allergy and IgE antibodies to food allergens in Swedish and Estonian schoolchildren

OBJECTIVE

To compare the prevalence of self-reported food allergy and IgE antibodies to food allergens in wheezing and non-wheezing Estonian and Swedish schoolchildren, in the light of the disparities in the standard of living, food consumption and prevalence of respiratory allergies that still exist between Estonia and the Scandinavian countries.

DESIGN AND SETTING

As a part of the ISAAC Phase II study, children from a random sample of schools in Tallinn in Estonia and Linköping and Ostersund in Sweden participated in skin prick tests to inhalant allergens and the parents replied to questionnaires. IgE antibodies against a panel of food allergens (egg white, milk, soy bean, fish, wheat and peanut) were taken from children with questionnaire-reported wheezing and a random sample of nonwheezing children.

SUBJECTS

Children aged 10-11 y.

RESULTS

The prevalence of self-reported food allergy was similar in Estonia and Sweden and about twice as high in wheezing children than in nonwheezing children. In Estonia, however, 3% of the children with perceived food allergy reported reactions from at least four different foods, as compared to 31% in Sweden. The prevalence of sensitisation to food allergens was similar in wheezing and nonwheezing children in Estonia (8%) while, in Swedish children, IgE antibodies to food allergens were more likely among wheezing children (Linköping 38 vs 11%, crude OR 5.1, 95% CI 2.2-11.6, and Ostersund 24 vs 7%, crude OR 4.1, 95% CI 1.9-8.5).

CONCLUSION

Our study suggests that IgE-mediated food reactions were less likely in Estonian schoolchildren. Moreover, the perception of food allergy and thereby the meaning of self-reported food allergy appears to be different in the two countries.

Trends in asthma, allergic rhinitis and eczema among Swedish conscripts from farming and non-farming environments. A nationwide study over three decades

BACKGROUND

Asthma and allergies are less common in children who have been raised in farming environments.

OBJECTIVES

To assess whether children who grow up in a farming environment have been protected against the general increase in atopic disorders in Sweden and whether other rural environments could also be protective.

METHOD

Linkage at an individual level of three national registers in Sweden: The Swedish Military Service Conscription Register (MSCR), the Register of the Total Population (RTP) and the Population and Housing Censuses (PHC). Asthma, allergic rhinitis and eczema at conscription were analysed in relation to area of residence, parental occupation, maternal age, family size and being the first born for 1 309 652 male conscripts in three successive cohorts born between 1952 and 1981.

RESULTS

Allergic rhinitis and eczema displayed a continuous increase throughout the study period, whereas the rise in asthma mainly occurred in conscripts born after 1961. Farming environments and rural living already provided protection from allergic rhinitis in conscripts born during the 1950s, but the protective effect was greater in later cohorts. An inverse association was observed between farm living and asthma, but mainly in conscripts born after 1970. The adjusted risk ratios for asthma in conscripts from farming vs. non-farming families were 1.00 (95% CI 0.93-1.07), 0.94 (95% CI 0.88-1.01) and 0.85 (95% CI 0.79-0.91) in conscripts born in 1952-1961, 1962-1971 and 1972-1981, respectively. Rural living per se had no effect on the occurrence of asthma. Eczema was less common in rural areas, but the time trend was similar in urban and rural areas.

CONCLUSIONS

Our findings suggest that environmental changes affecting the whole of society have promoted an increase in asthma, allergic rhinitis and eczema in both farming and non-farming environments. A lower risk of allergic rhinitis in conscripts whose parents were involved in farming was observed in all birth cohorts, whereas the protective effect of growing up on a farm on the risk of asthma appears to be a fairly recent phenomenon.

High body mass index, asthma and allergy in Swedish schoolchildren participating in the International Study of Asthma and Allergies in Childhood: Phase II

AIM

To assess the relationship between high body mass index (BMI) and asthma and atopic manifestations in 12-y-old children.

METHODS

The relationship between high BMI and asthma symptoms was studied in 457 sixth-grade children, with (n = 161) and without (n = 296) current wheeze. High BMI was defined as > or = 75th percentile of gender-specific BMI reference values for Swedish children at 12 y of age; overweight as a subgroup of high BMI was defined as > or = 95th percentile. Children with a BMI < 75th percentile served as controls. Questionnaires were used to assess asthmatic and allergic symptoms, and bronchial hyperresponsiveness was assessed by hypertonic saline provocation tests.

RESULTS

Current wheeze was associated with high BMI after adjustment for confounding factors (adjusted OR 1.7, 95% CI 1.0-2.5) and overweight had an even more pronounced effect (adjusted OR 1.9, 95% CI 1.0-3.6). In addition, asthma severity was associated with high BMI, as evaluated by the number of wheezing episodes during the previous 12 mo among the wheezing children (adjusted OR 2.0, 95% CI 1.0-4.0). There was also an association between high BMI and the presence of eczema in wheezing children (adjusted OR 2.2, 95% CI 1.0-4.6). However, high BMI was not significantly associated with hay fever, positive skin prick tests or bronchial hyperresponsiveness.

CONCLUSION

The study confirms and extends a previously observed relationship between BMI and the presence of wheezing and asthma.

Early determinants of first hospital admissions for asthma and acute bronchitis among Swedish children

AIM

To assess the changing impact of prenatal and perinatal factors with increasing age on first admissions for asthma and acute bronchitis.

METHODS

The Swedish Medical Birth Registry was linked to the National Hospital Discharge Registry for 214,276 Swedish children born in 1987 and 1988. The linkage comprised first admissions for acute bronchitis or asthma from 1987 to 1995. First admissions for gastroenteritis were included to distinguish between factors specific to asthma or bronchitis and non-specific factors related to an increased risk of hospital admission.

RESULTS

Admissions for asthma and acute bronchitis before 2 y of age had a close dose-response relationship with maternal smoking, low gestational age, low maternal age and older siblings. Very premature children exposed to more than 9 cigarettes a day in utero ran a 10 times higher risk of hospitalization than postmature children without exposure to maternal smoking. However, the proportion of admissions attributed to maternal smoking was only 4.7% after adjustments for significant covariates. The number of significant determinants declined in children with their first admission for asthma after 2 y of age but male gender and low educational level were independent determinants in all age groups. Older siblings were related to an increased risk of first asthma admission before 2 y of age but a slightly reduced risk of first admission after 2 y of age.

CONCLUSION

This study illustrates the varied epidemiology of asthma in different age groups. Maternal smoking was an important determinant for admission before 2 y of age but mainly in combination with other factors. The decline in hospital admissions in early childhood would therefore be small, even after the elimination of maternal smoking, if other significant perinatal and socioeconomic factors were unchanged.

Wheezing in relation to atopy and environmental factors in Estonian and Swedish schoolchildren

BACKGROUND

The prevalence of asthma and allergic diseases is significantly lower in post socialist Eastern Europe than in Western industrialized countries. The reason for this difference is largely unknown. Different types of childhood wheezing could be related to different risk factors.

OBJECTIVE

To compare the prevalence of respiratory symptoms, asthma and atopic diseases among Estonian and Swedish schoolchildren and to evaluate characteristics for wheezing in the two countries.

METHODS

In a prevalence study, population-based random samples of 10-11-year-old schoolchildren in Tallinn (n = 979), Estonia and in Linköping (n = 911) and Ostersund (n = 1197), Sweden were studied by a parental questionnaire and skin prick tests (SPT). All 275 children with wheeze in the past 12 months and 710 randomly selected controls within the original cohorts were invited to a case-control study involving a parental questionnaire, examination for flexural dermatitis and bronchial challenge with hypertonic saline. The study adhered to the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol.

RESULTS

The prevalence of current wheezing was similar (8-10%) in the three centres, while diagnosed asthma and atopic symptoms were more common in Sweden and cold-related respiratory symptoms were more prevalent in Estonia. Frequent wheezing was more common in Sweden than in Estonia (but significantly so only in Ostersund). Wheezing children in Sweden had a high rate of positive SPT (49% in Linköping and 58% in Ostersund) bronchial hyper-responsiveness (BHR) (48% in Linköping and Ostersund) and anti-asthmatic treatment (63% in Linköping and 81% in Ostersund). In Estonia, the proportion of wheezing children with positive SPT, BHR and anti-asthmatic treatment was only 26%, 13% and 17%, respectively. Domestic crowding was inversely related to wheezing in one of the study areas (Ostersund). The mean baseline forced expiratory volume in one second (FEV1) was higher in Estonia than in Sweden, both in wheezing and non-wheezing children.

CONCLUSIONS

Our study suggested that although wheezing symptoms were equally common in Estonia and Sweden, they were less severe in Estonia. More frequent symptoms and a high rate of atopy, BHR and anti-asthmatic medication characterized wheezing children in Sweden. In contrast, BHR, atopy and medication were uncommon among wheezing children in Estonia.

[Great geographic variations in the prevalence of asthma and allergy. International population studies to explain the associative factors]

During the 1990's the international variation in the prevalence of asthma and allergy was studied in young adults (European Community Respiratory Health Survey, ECRHS) and in children (International Study of Asthma and Allergy in Children, ISAAC). The prevalence of asthma and allergy was highest in the United Kingdom, North America, Australia and New Zealand, lower in the Baltic countries and very low in some of the poorest republics of the former USSR. Children that lived in the countryside during the first year of life had a lower prevalence of atopic disease as teenager while in adults farmers had the highest prevalence of occupational asthma. In both investigations a negative association was found between having pets as a child and atopic sensitisation. This association could, however, be related to selection mechanisms. In a three year follow-up of the Swedish part of the ECRHS the incidence of asthma was higher in smokers than non-smokers. Passive smoking was associated with respiratory symptoms in both children and adults. Follow-ups of both studies are being planned or performed. Further analyses of the geographic differences may explain the reason for the rapid increase of asthma and allergy in the Western world.

[Young woman dies of water intoxication after taking one tablet of ecstasy. Today's drug panorama calls for increased vigilance in health care]

Increasing numbers of reports demonstrate that low doses of ecstasy (3,4-methylenedioxymethamphetamine--MDMA) may induce life-threatening conditions, such as hyperthermia and water intoxication. These lethal states are rarely due to overdose, and young women seem to be at particular risk. This is a case report of a 20-year-old previously healthy Swedish girl. She died of water intoxication and cerebral edema approximately 24 hours after ingestion of one tablet of "ecstasy" at a rave club in Amsterdam. Clinical findings and laboratory data suggested a syndrome of inappropriate antidiuretic hormone secretion (SIADH) induced by MDMA in combination with excessive intake of water. This case illustrates the dire consequences of the present drug abuse panorama, if the increasing need for awareness of potentially lethal complications is not met within emergency health care services.

Atopy among schoolchildren in northern and southern Sweden in relation to pet ownership and early life events

Studies have suggested a higher prevalence of asthma and allergies in northern, as compared to southern, Scandinavia. The aim of this study was to evaluate regional differences in atopy in relation to pet ownership and certain early life events among schoolchildren (n=2108) aged 10-11 years from Linköping in southern Sweden and Ostersund in northern Sweden. The parents completed a questionnaire, comprising questions on home environment, heredity, socio-economic conditions, and the core questions on symptoms from the International Study of Asthma and Allergies in Childhood. The children were skin-prick tested to eight common inhalant allergens. Information on maternal smoking habits, gestational age, and anthropometric measures were obtained from the Swedish Medical Birth Registry. The prevalence of atopic symptoms and sensitization to pollen were similar in Ostersund and in Linköping. A higher prevalence of sensitization to animal dander among children in Ostersund could be linked to a higher occurrence of pets in the community. Current cat ownership was related to less sensitivity to cat allergen but only in children with an atopic heredity. Ponderal index >30 kg/m3 was related to an increased risk of atopic sensitization, both in Linköping (adjusted odds ratio 2.1; 95% confidence interval 1.1-4.0) and in Ostersund (adjusted odds ratio 2.0; 95% confidence interval 1.1-3.5). Maternal smoking during pregnancy was related to an increased risk of atopic sensitization among children in Linköping, whereas current smoking was associated with a decreased risk of sensitization in Ostersund. In conclusion, we demonstrated that a high occurrence of pets in the community was associated with sensitization, whereas atopic symptoms were essentially unaffected. This study has also suggested an association between body size at birth and atopic sensitization at 10-11 years of age.

Similar prevalence of respiratory symptoms and atopy in Estonian schoolchildren with changing lifestyle over 4 yrs

The prevalence of allergic sensitization and clinical manifestations is low in Eastern Europe, despite a continuous increase in industrialized countries with a market economy. The aim of the present study was to study changes in the prevalence of respiratory symptoms and atopic sensitization over time among schoolchildren in Estonia, in relation to environmental changes as the country transformed into a market economy. A cross-sectional study of 10-yr-old children was carried out between October 1996 and April 1997, employing a questionnaire regarding the prevalence of wheezing, rhinitis and itching rash (n=979) and skin-prick tests with seven inhalant allergens (n=640). The results were compared with those of a similar study performed in 1992-1993. The 12-month prevalence of wheeze was 8.3%, as compared to 9.4% in 1992-1993 (NS) and of asthma was 2.5 versus 3.2% (NS). The prevalence of a positive skin-prick test result was 14.3% in both studies. Furthermore, the prevalence of sensitivity to the individual allergens was similar, except for a significantly higher prevalence of dog sensitivity in 1996-1997 (4.7 versus 2.0%). The prevalence of respiratory and other potentially allergic symptoms, as well as the prevalence of atopic sensitization, remains low in Estonian 10-yr-old children, despite a changing lifestyle over the past 4 yrs. This could indicate that the time period was too short for environmental changes to affect the prevalence of allergy, or alternatively that risk factors associated with a "western lifestyle" are of particular significance earlier in life.

Changes in prevalence and severity of asthma among schoolchildren in a Swedish district between 1985 and 1995

The same questionnaire and study design was used in two surveys of asthma among all the children attending the 9-y compulsory school in Sundsvall in 1985 (n = 10527) and 1995 (n = 9165). A detailed questionnaire was distributed by post to the parents of all children who had answered in the affirmative to a simple screening question on asthmatic symptoms at the beginning of the autumn term. The questionnaire contained detailed questions on symptoms and asthma management. Our findings indicated a moderate increase in reported asthma-like symptoms and physician-diagnosed asthma between 1985 and 1995. The severity of symptoms was unchanged, despite a large community-based asthma campaign and a tenfold increase in the number of children receiving inhaled steroids. A validation analysis included an interview by a physician, a skin prick test, determination of specific IgE antibodies and spirometry. The oral interviews suggested that undertreatment was common. Many children had adequate medication at home, but this medication was not used properly. Finally, all 13-14-y-old children also replied to written and video questionnaires from the International Study of Asthma and Allergies in Childhood (ISAAC). It is likely that differences in study design explained the much higher prevalence of wheezing in this part of the study.

Perinatal risk factors for atopic disease in conscripts

BACKGROUND

There is evidence to suggest that atopic disease in adulthood could be manifestations of events in early life.

OBJECTIVES

To investigate the relationship between perinatal risk factors and the prevalence of allergic rhinitis and asthma in conscripts.

METHODS

A retrospective cohort study, where information from the Military Service Enrolment Register was linked to the national Medical Birth Register. The study included 149 398 male conscripts who were born in Sweden in 1973, 1974 and 1975. Outcome measures were current asthma and allergic rhinitis recognized at the compulsory military conscript examinations.

RESULTS

Unifactorial analyses demonstrated that number of older siblings, young maternal age, multiple gestation, prematurity, low birth weight, growth retardation and perinatal asphyxia were all significantly related to a decreased risk of allergic rhinitis among male conscripts. The prevalence rates of allergic rhinitis among conscripts with and without older siblings were 14.1% and 16.2%, respectively (odds ratio 0.85; 95% confidence interval 0.82-0.87). The prevalence rates of allergic rhinitis among those with term birth (>36 weeks), moderately preterm birth (33-36 weeks) and very preterm birth (<33 weeks) were 15.2%, 13.1% and 11.6%, respectively. Older siblings, multiple gestation and young maternal age were highly significant independent determinants of allergic rhinitis. By contrast, the effects of prematurity, low birthweight and asphyxia were weaker and highly correlated. The only independent determinants of asthma were maternal age, birthweight and multiple gestation. Furthermore, maternal age and birthweight had opposite effects on asthma and allergic rhinitis.

CONCLUSIONS

In contrast to asthma, allergic rhinitis in young adult men was strongly associated with perinatal events. This may reflect the close relationship between allergic rhinitis and atopic sensitization, whereas asthma has a more multifactorial aetiology.

Prevalence of bronchial hyperreactivity as determined by several methods among Estonian schoolchildren

There is a lack of established criteria to identify asthma and bronchial hyperreactivity (BHR) in epidemiological studies, although both conditions appear to bear some relationship to atopy, at least in children. Recent studies indicate a low prevalence of atopy in former Socialist countries in Europe, yet the prevalence of BHR has been reported to be high. We have analysed the relationship between the outcome of various lung function tests, atopy and clinical symptoms of bronchial asthma in an epidemiological survey of Estonian 10-12 year old schoolchildren. Metacholine provocation test (four steps with the cumulative doses 100, 300, 700 and 1100 micrograms), exercise challenge test and PEF-variability over two weeks were done in 806 children in Tallinn (coastal, industrialised city) and 774 children in Tartu (inland, university town). A positive response to the metacholine challenge test was recorded in 19% in Tallinn and in 32% in Tartu (p < 0.001). A similar tendency was observed for a more than 15% decrease of FEV1 in the exercise challenge test, i.e. 6% in Tallinn and 18% in Tartu. There was only a weak relationship between BHR, as defined by either a positive metacholine challenge and/or exercise test, diagnosed asthma and reported wheezing. Thus, 47% of the wheezing children and 30% of the children with asthma had negative test results. Only 17% of the children with a positive metacholine challenge were atopic, as defined by at least one positive skin prick test. In conclusion, none of the methods employed to assess bronchial hyperresponsiveness were very useful for the identification of wheezing and asthmatic children in this epidemiological study. In contrast to the results of studies in Western Europe, most children with bronchial hyperreactivity in Estonia are not atopic.

The prevalence of atopic sensitization and respiratory symptoms among Estonian schoolchildren

OBJECTIVES

To assess the prevalence of atopic sensitization, asthma and other respiratory disorders among Estonian schoolchildren in a coastal industrial city and an inland university town, i.e. Tallinn and Tartu.

DESIGN

Prevalence surveys by self-completion of questionnaires by the children's parents and skin-prick tests (SPT) with eight common allergens.

SUBJECTS

A total of 1519 schoolchildren aged 10-12 years.

RESULTS

The prevalence of positive SPT was 11.0%, with significant differences between Tallinn (14.3%) and Tartu (8.1%), RR 1.89, 95% CI 1.13-2.73, P < 0.001. Dermatophagoides pteronyssinus, cat (6.1%) and timothy (4.8%) were the most prevalent sensitizing allergens in Tallinn. The prevalence of asthma diagnosed by a doctor was 2.9%, of wheezing 7.0% and of rhinoconjunctivitis 7.4%, as assessed by questionnaire.

CONCLUSIONS

The prevalence of atopy as defined by a positive SPT, asthma and corresponding respiratory symptoms is low in Estonia similar to other post-socialist countries of Europe. The lower prevalence rates of allergic disorders are possibly explained with differences in lifestyle and living conditions. The relative significance of air pollution was apparently similar in Estonia and western Europe, however, as indicated by the higher prevalence of sensitization in the more polluted city, Tallinn than in Tartu.

Risk factors for respiratory symptoms and atopic sensitisation in the Baltic area

Recent studies have indicated that atopic sensitisation is uncommon while respiratory symptoms are common among schoolchildren in Eastern Europe. Risk factors for respiratory symptoms and atopic sensitisation were evaluated in a cross sectional study involving 2594 schoolchildren (10-12 years) from Sweden (n = 665), Poland (n = 410), and Estonia (n = 1519). The measurements included parental questionnaires and skin prick tests with eight standardised allergens. Multiple logistic analyses demonstrated that atopic heredity was a significant independent risk factor for respiratory symptoms and atopic sensitisation in all the countries. Current dampness and maternal smoking were related to respiratory symptoms whereas domestic crowding, male gender, and passive smoking during infancy were related to atopic sensitisation. Current maternal smoking had a strong dose response association with current coughing attacks (nocturnal cough > 4 weeks or exercise induced coughing attacks) but only in Eastern Europe. A strong inverse relationship was recorded between domestic crowding and sensitisation as the risk for sensitisation increased with decreasing number of persons per room in the household (odds ratio (OR) 0.58, 95% confidence interval (CI) 0.43 to 0.77). Exposure to tobacco smoke at home during infancy was a risk factor for atopic sensitisation but only to animal dander and only in Eastern Europe (OR 1.41, 95% CI 1.03 to 1.93). In conclusion, there were small differences in the pattern of risk factors between Eastern and Western Europe. The only exception was environmental tobacco smoke being a risk factor only in Eastern Europe. The study also suggests that factors related to domestic crowding protect against atopic sensitisation in Estonia and Poland. A higher standard of living with less crowding may give rise to an increasing prevalence of atopic sensitisation also in Eastern Europe.

Atopic sensitization and respiratory symptoms among Polish and Swedish school children

Allergic sensitization and symptoms from the airways in relation to air pollution were compared in 10-12-year-old school children (n = 1113) from urban Konin in central Poland and both urban and rural parts of Sundsvall in northern Sweden. The measurements included parental questionnaires, skin-prick tests and serial peak flow measurements during 2 weeks with simultaneous monitoring of outdoor air pollutants. The skin-prick test technique was validated by IgE antibody determinations. The levels of common industrial pollutants, SO2 and smoke particles were much higher in Konin than in urban Sundsvall and the levels of NO2 were similar. Various respiratory symptoms were more often reported among school children in Konin (except for wheezing and diagnosed asthma). Multiple logistic regression analyses yielded the following increased odds ratios for children in Konin as compared with the reference group (rural Sundsvall): chest tightness and breathlessness 3.48 (95% confidence interval 2.08-5.82), exercise-induced coughing attacks 3.69 (95% confidence interval 1.68-8.10), recurrent episodes of common cold 2.79 (95% confidence interval 1.53-5.09) and prolonged cough 4.89 (95% confidence interval 2.59-9.23). In contrast, as compared with rural Sundsvall, the adjusted odds ratio for a positive skin-prick test was decreased in Konin, but increased in urban Sundsvall, 0.58 (95% confidence interval 0.37-0.91) and 1.67 (95% confidence interval 1.15-2.42) respectively. The study confirms that living in urban, as compared with rural areas, is associated with an increased prevalence of respiratory symptoms and sensitization to allergens. These differences could be explained by air pollution. Respiratory symptoms were more common in a similar urban group of Polish children who were exposed to even higher levels of air pollution. These children, however, had a much lower prevalence of sensitization to allergens, as compared with the Swedish children. This indicates that differences in lifestyle and standard of living between western Europe and a former socialist country influences the prevalence of atopy.

Personal NO2 exposure monitoring shows high exposure among ice-skating schoolchildren

A method for measuring personal nitrogen dioxide (NO2) exposure, using passive samplers, was tested among schoolchildren. Activity patterns and NO2 exposure levels were studied in relation to urban and rural living. Stationary air monitoring data indicated that the urban children were supposed to be exposed to NO2 levels that were among the highest in Sweden. It was shown that NO2 levels measured at the stationary air monitoring station were not representative for the children's exposure. The children spent 90% of their time indoors; only a small percentage of their time was spent in transit. The median daily NO2 exposure level in the urban area (13 micrograms NO2/m3, 7 ppb) was significantly higher (p < .001) than in the rural area (7 micrograms NO2/m3, 4 ppb). The most important source of exposure was the indoor ice-skating arenas, where levels up to 8,000 micrograms NO2/m3 (4 240 ppb) were measured during 1-h periods.

Asthma in schoolchildren. Factors influencing morbidity in a Swedish survey

In a survey of asthma among schoolchildren, a questionnaire was sent to the parents of 10,527 children aged 7-16 years. A group of 420 children with asthma was thereafter identified. Their asthma symptoms had caused little absence from school (none in the past 6 months in 60% of the group, and greater than 5 days in only 13%). During the preceding year 40% of the group had had more than 10 days of restricted physical activity due to asthma. Severe symptoms due to undertreatment were uncommon. Although 68 children were receiving no medication, most of them appeared to have only mild symptoms, and the parents requested aerosol inhaler in only ten cases. Symptoms at school were usually related to sporting activities. In 40% of the total asthma group the symptoms were unknown to the school health service before the survey. Dissatisfaction with the service was expressed by 24% of the parents of asthmatic children.

Prevalence of bronchial asthma among schoolchildren in a Swedish district

The prevalence of asthma among 10,527 children aged 7-16 years was investigated in 1985. Children were assigned to the asthma group when replies to a questionnaire stated that at least two of four stipulated symptoms had been experienced in the preceding year. A validation study, comprising exploration of medical history, pulmonary auscultation and physiological tests (spirometry and methacholine inhalation challenge) was performed in 73 children. The overall prevalence of asthma was 4%. The most common symptom-inducing factors were physical exertion, upper respiratory tract infection, contact with animals and tobacco smoke. The methacholine test had limited value as a diagnostic aid, being positive in only 25% of children with a clear history of asthma.