Body mass index, asthma and allergic rhinoconjunctivitis in Swedish conscripts—a national cohort study over three decades

SummaryObesity and overweight have been associated with an increased risk of asthma in children as well as adults. The association between atopy and body mass index (BMI) is less clear. It has also been suggested that the link between a high BMI and asthma could be a recent phenomenon. The objective of this study was to assess whether the association with BMI differed between allergic rhinoconjunctivitis and asthma and if these associations have changed over time.The Swedish Military Service Conscription Register was linked to the Register of the Total Population and the Population and Housing Censuses. Asthma (with and without allergic rhinoconjunctivitis) and allergic rhinoconjunctivitis at conscription were analysed in relation to BMI for 1,247,038 male conscripts in successive cohorts born between 1952 and 1977. Obesity was associated with asthma without allergic rhinoconjunctivitis, adjusted OR 1.53 (95% CI 1.43–1.63), and with asthma with allergic rhinoconjunctivitis, adjusted OR 1.34 (95% CI 1.20–1.50), but not with allergic rhinoconjunctivitis, OR 1.00 (95% CI 0.97–1.03) after multivariate analyses with adjustments for confounders. The odds ratios were similar in three successive cohorts (conscripts born in 1952–1961, 1962–1971 and 1972–1977). Underweight was associated with a slightly increased risk for all three conditions. The increased risk of asthma in young Swedish men with obesity has remained unchanged over a period of three decades

An expert assessment on climate change and health – with a European focus on lungs and allergies

Background For almost 20 years, the Intergovernmental Panel on Climate Change has been assessing the potential health risks associated with climate change; with increasingly convincing evidence that climate change presents existing impacts on human health. In industrialized countries climate change may further affect public health and in particular respiratory health, through existing health stressors, including, anticipated increased number of deaths and acute morbidity due to heat waves; increased frequency of cardiopulmonary events due to higher concentrations of air pollutants; and altered spatial and temporal distribution of allergens and some infectious disease vectors. Additionally exposure to moulds and contaminants from water damaged buildings may increase. Methods We undertook an expert elicitation amongst European researchers engaged in environmental medicine or respiratory health. All experts were actively publishing researchers on lung disease and air pollution, climate and health or a closely related research. We conducted an online questionnaire on proposed causal diagrams and determined levels of confidence that climate change will have an impact on a series of stressors. In a workshop following the online questionnaire, half of the experts further discussed the results and reasons for differences in assessments of the state of knowledge on exposures and health effects. Results Out of 16 experts, 100% expressed high to very high confidence that climate change would increase the frequency of heat waves. At least half expressed high or very high confidence that climate change would increase levels of pollen (50%), particulate matter (PM2.5) (55%), and ozone (70%). While clarity is needed around the impacts of increased exposures to health impacts of some stressors, including ozone and particulate matter levels, it was noted that definitive knowledge is not a prerequisite for policy action. Information to the public, preventive measures, monitoring and warning systems were among the most commonly mentioned preventative actions. Conclusions This group of experts identifies clear health risks associated with climate change, and express opinions about these risks even while they do not necessarily regard themselves as covering all areas of expertise. Since some changes in exposure have already been observed, the consensus is that there is already a scientific basis for preventative action, and that the associated adaptation and mitigation policies should also be evidence based

Associations of preconception exposure to air pollution and greenness with offspring asthma and hay fever

We investigated if greenness and air pollution exposure in parents’ childhood affect offspring asthma and hay fever, and if effects were mediated through parental asthma, pregnancy greenness/pollution exposure, and offspring exposure. We analysed 1106 parents with 1949 offspring (mean age 35 and 6) from the Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) generation study. Mean particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), black carbon (BC), ozone (O3) (µg/m3) and greenness (normalized difference vegetation index (NDVI)) were calculated for parents 0-18 years old and offspring 0-10 years old, and were categorised in tertiles. We performed logistic regression and mediation analyses for two-pollutant models (clustered by family and centre, stratified by parental lines, and adjusted for grandparental asthma and education). Maternal medium PM2.5 and PM10 exposure was associated with higher offspring asthma risk (odds ratio (OR) 2.23, 95%CI 1.32-3.78, OR 2.27, 95%CI 1.36-3.80), and paternal high BC exposure with lower asthma risk (OR 0.31, 95%CI 0.11-0.87). Hay fever risk increased for offspring of fathers with medium O3 exposure (OR 4.15, 95%CI 1.28-13.50) and mothers with high PM10 exposure (OR 2.66, 95%CI 1.19-5.91). The effect of maternal PM10 exposure on offspring asthma was direct, while for hay fever, it was mediated through exposures in pregnancy and offspring’s own exposures. Paternal O3 exposure had a direct effect on offspring hay fever. To conclude, parental exposure to air pollution appears to influence the risk of asthma and allergies in future offspring

A retrospective population based trend analysis on hospital admissions for lower respiratory illness among Swedish children from 1987 to 2000

BACKGROUND: Data relating to hospital admissions of very young children for wheezing illness have been conflicting. Our primary aim was to assess whether a previous increase in hospital admissions for lower respiratory illness had continued in young Swedish children. We have included re-admissions in our analyses in order to evaluate the burden of lower respiratory illness in very young children. We have also assessed whether changes in the labelling of symptoms have affected the time trend. METHODS: A retrospective, population based study was conducted to assess the time trend in admissions and re-admissions for lower respiratory illness. Data were obtained from the Swedish Hospital Discharge Register for all children with a first hospital admission before nine years of age, a total of 109,176 children. The register covers more than 98% of all hospital admissions in Sweden. The coding of diagnoses was based on ICD-9 from 1987 to 1996 and ICD-10 from 1997. RESULTS: The first admission rates declined significantly in children with a first admission after two years of age. However, an increasing admission trend was observed in children aged less than one year and 35% of first admissions occurred in this age group. The annual increase was 3.8% (95% CI 1.3–6.3) in boys and 5.0% (95% CI 2.4–7.6) in girls. A diagnostic shift appeared to occur when ICD-10 was introduced in 1997. The asthma and pneumonia admission rate in children aged less than one year levelled off, whereas the increase in admissions for bronchitis continued. The re-admission rates for asthma decreased and the probability of re-admission was higher in boys. National drug statistics demonstrated a substantial increase in the delivery of inhaled steroids to all age groups but most prescriptions occurred to children aged one year or more. CONCLUSION: Hospital admissions for lower respiratory illness are still increasing in children aged <1 year. Our findings are in line with other recent studies suggesting a change in the responsiveness to viral infections in very young children, but changes in admission criteria cannot be excluded. An increased use of inhaled steroids may have contributed to decreasing re-admission rates

Does traffic exhaust contribute to the development of asthma and allergic sensitization in children: findings from recent cohort studies

The aim of this review was to assess the evidence from recent prospective studies that long-term traffic pollution could contribute to the development of asthma-like symptoms and allergic sensitization in children. We have reviewed cohort studies published since 2002 and found in PubMed in Oct 2008. In all, 13 papers based on data from 9 cohorts have evaluated the relationship between traffic exposure and respiratory health. All surveys reported associations with at least some of the studied respiratory symptoms. The outcome varied, however, according to the age of the child. Nevertheless, the consistency in the results indicates that traffic exhaust contributes to the development of respiratory symptoms in healthy children. Potential effects of traffic exhaust on the development of allergic sensitization were only assessed in the four European birth cohorts. Long-term exposure to outdoor air pollutants had no association with sensitization in ten-year-old schoolchildren in Norway. In contrast, German, Dutch and Swedish preschool children had an increased risk of sensitization related to traffic exhaust despite fairly similar levels of outdoor air pollution as in Norway. Traffic-related effects on sensitization could be restricted to individuals with a specific genetic polymorphism. Assessment of gene-environment interactions on sensitization has so far only been carried out in a subgroup of the Swedish birth cohort. Further genetic association studies are required and may identify individuals vulnerable to adverse effects from traffic-related pollutants. Future studies should also evaluate effects of traffic exhaust on the development and long term outcome of different phenotypes of asthma and wheezing symptoms

Father's environment before conception and asthma risk in his children: a multi-generation analysis of the Respiratory Health In Northern Europe study

Whereas it is generally accepted that maternal environment plays a key role in child health, emerging evidence suggests that paternal environment before conception also impacts child health. We aimed to investigate the association between children's asthma risk and parental smoking and welding exposures prior to conception.; In a longitudinal, multi-country study, parents of 24 168 offspring aged 2-51 years provided information on their life-course smoking habits, occupational exposure to welding and metal fumes, and offspring's asthma before/after age 10 years and hay fever. Logistic regressions investigated the relevant associations controlled for age, study centre, parental characteristics (age, asthma, education) and clustering by family.; Non-allergic early-onset asthma (asthma without hay fever, present in 5.8%) was more common in the offspring with fathers who smoked before conception {odds ratio [OR] = 1.68 [95% confidence interval (CI) = 1.18-2.41]}, whereas mothers' smoking before conception did not predict offspring asthma. The risk was highest if father started smoking before age 15 years [3.24 (1.67-6.27)], even if he stopped more than 5 years before conception [2.68 (1.17-6.13)]. Fathers' pre-conception welding was independently associated with non-allergic asthma in his offspring [1.80 (1.29-2.50)]. There was no effect if the father started welding or smoking after birth. The associations were consistent across countries.; Environmental exposures in young men appear to influence the respiratory health of their offspring born many years later. Influences during susceptible stages of spermatocyte development might be important and needs further investigation in humans. We hypothesize that protecting young men from harmful exposures may lead to improved respiratory health in future generations

A retrospective population based trend analysis on hospital admissions for lower respiratory illness among Swedish children from 1987 to 2000

Abstract Background Data relating to hospital admissions of very young children for wheezing illness have been conflicting. Our primary aim was to assess whether a previous increase in hospital admissions for lower respiratory illness had continued in young Swedish children. We have included re-admissions in our analyses in order to evaluate the burden of lower respiratory illness in very young children. We have also assessed whether changes in the labelling of symptoms have affected the time trend. Methods A retrospective, population based study was conducted to assess the time trend in admissions and re-admissions for lower respiratory illness. Data were obtained from the Swedish Hospital Discharge Register for all children with a first hospital admission before nine years of age, a total of 109,176 children. The register covers more than 98% of all hospital admissions in Sweden. The coding of diagnoses was based on ICD-9 from 1987 to 1996 and ICD-10 from 1997. Results The first admission rates declined significantly in children with a first admission after two years of age. However, an increasing admission trend was observed in children aged less than one year and 35% of first admissions occurred in this age group. The annual increase was 3.8% (95% CI 1.3–6.3) in boys and 5.0% (95% CI 2.4–7.6) in girls. A diagnostic shift appeared to occur when ICD-10 was introduced in 1997. The asthma and pneumonia admission rate in children aged less than one year levelled off, whereas the increase in admissions for bronchitis continued. The re-admission rates for asthma decreased and the probability of re-admission was higher in boys. National drug statistics demonstrated a substantial increase in the delivery of inhaled steroids to all age groups but most prescriptions occurred to children aged one year or more. Conclusion Hospital admissions for lower respiratory illness are still increasing in children aged <1 year. Our findings are in line with other recent studies suggesting a change in the responsiveness to viral infections in very young children, but changes in admission criteria cannot be excluded. An increased use of inhaled steroids may have contributed to decreasing re-admission rates.</p

Asthma heredity, cord blood IgE and asthma-related symptoms and medication in adulthood: a long-term follow-up in a Swedish birth cohort

Johann Wolfgang von Goethe (1749-1832) ORIGINAL PUBLICATIONS This thesis is based on the following four papers, which will be referred to in the text by their Roman numerals