Association between obesity and asthma in 4-11 year old children in the UK

BACKGROUND: There is evidence of a positive association between asthma and obesity in adults and in children. We investigated, in a large sample of English and Scottish primary school children, whether there is a consistent association between fatness and asthma symptoms in Britain. METHODS: A cross sectional analysis was made of 18 218 children aged 4-11 years who participated in the 1993 or 1994 surveys of the National Study of Health and Growth (NSHG). Children belonged either to English or Scottish representative samples, or an English inner city sample. Asthma attacks in the previous year, occasional wheeze, or persistent wheeze were the symptoms used in the analysis. Body mass index (BMI) and the sum of triceps and subscapular skinfolds converted to standard deviation scores (SDS) were used to assess levels of fatness. RESULTS: A total of 14 908 children (81.8%) were included in the analysis. In the multiple logistic analysis BMI and asthma (asthma attacks or wheeze) were associated in the representative sample (OR for the comparison of the 10th and 90th centiles of BMI 1.28, 95% CI 1.11 to 1.48), but sum of skinfolds was unrelated to asthma symptoms in most analyses. The association between asthma and BMI was stronger in girls than in boys in the inner city sample, but less convincingly in the representative sample. CONCLUSIONS: Levels of obesity are associated with asthma symptoms regardless of ethnicity. The association is more consistent for BMI than for sum of skinfolds, partly because obese children are more advanced in their maturation than other children. There is some evidence that, as in adults, the association is stronger in girls than in boys, but only in the multiethnic inner city sample.     

Lung function, respiratory illness, and passive smoking in British primary school children.

BACKGROUND: Many studies have reported a significant association between parents' smoking and reduced lung function in their children, but often the association has been found to be significant only in relation to maternal smoking. There have been few epidemiological studies on this topic in Britain. METHODS: Spirometry, in 2756 children aged 6.50-11.99 years, was carried out in a representative sample of English children, an inner city and ethnic minority sample, and a Scottish sample. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and forced expiratory flow rates of 25-75% and 75-85% (FEF25-75 and FEF75-85) were measured and standardised scores obtained separately for the English representative sample, the Scottish sample and subgroups in the inner city sample, white and Afro-Caribbean children and those originating from the Indian subcontinent. Multiple regression analyses were used to assess associations of FVC, FEV1, FEF25-75 and FEF75-85 with the passive smoking and respiratory illness, with adjustment for a large number of potential confounders. Passive smoking was defined in terms of reported number of cigarettes smoked at home by each parent. The respiratory symptoms and illnesses assessed were wheeze, asthma and bronchitis attacks, cough in the morning, and cough at any other time as reported by parents. RESULTS: Maternal smoking, but not paternal smoking, was associated with reduced FEF25-75 and FEF75-85 in boys. No association was found between passive smoking and lung function in girls, but in an analysis including both sexes the interaction of sex and parental smoking on lung function was not significant. With few exceptions, FEV1, FEF25-75 and FEF75-85 were reduced in children with wheeze and asthma attacks. CONCLUSIONS: The effect of passive smoking may depend on the close contact of a parent with a susceptible child as only maternal smoking in boys was significantly associated with impaired lung function. However, this explanation remains unsubstantiated. A parent's report of wheeze and asthma attacks in the child is reflected in reduced lung function.     

Exercise-induced bronchoconstriction by ethnicity and presence of asthma in British nine year olds.

BACKGROUND: The prevalence of exercise-induced bronchoconstriction among British children by ethnicity has not been studied. METHODS: Peak expiratory flow rate (PEFR) was measured before and after an exercise challenge test using a cycle ergometer in 593 nine year olds from Scottish and inner city English schools. Logistic regression analysis was carried out to assess the association between changes in PEFR with exercise by reported asthma, ethnicity, and sex. RESULTS: The probability of exercise-induced bronchoconstriction was greater among the asthmatics than in either the children without asthma attacks or wheeze, or in the children with only wheeze (p < 0.01). Asian children were 3.6 times more likely to have exercise-induced bronchoconstriction than white inner city children, and also were more likely to have exercise-induced bronchoconstriction than those from the other ethnic groups (p < 0.01). CONCLUSION: Exercise challenge can assess the prevalence of asthma in the community and detect under-reporting of asthma in ethnic minorities.     

Consumption of fresh fruit rich in vitamin C and wheezing symptoms in children. SIDRIA Collaborative Group, Italy (Italian Studies on Respiratory Disorders in Children and the Environment)

BACKGROUND: A beneficial effect of fresh fruit consumption on lung function has been observed in several studies. The epidemiological evidence of the effect on respiratory symptoms and asthma is limited. The consumption of fruit rich in vitamin C was examined in relation to wheezing and other respiratory symptoms in cross sectional and follow up studies of Italian children. METHODS: Standardised respiratory questionnaires were filled in by parents of 18 737 children aged 6-7 years living in eight areas of Northern and Central Italy. The winter intake of citrus fruit and kiwi fruit by the children was categorised as less than once per week, 1-2 per week, 3-4 per week, and 5-7 per week. A subset of 4104 children from two areas was reinvestigated after one year using a second parental questionnaire to record the occurrence of wheezing symptoms over the intervening period. RESULTS: In the cross sectional analysis, after controlling for several confounders (sex, study area, paternal education, household density, maternal smoking, paternal smoking, dampness or mould in the child's bedroom, parental asthma), intake of citrus fruit or kiwi fruit was a highly significant protective factor for wheeze in the last 12 months (odds ratio (OR) = 0.66, 95% confidence intervals (CI) 0.55 to 0.78, for those eating fruit 5-7 times per week compared with less than once per week), shortness of breath with wheeze (OR = 0.68, 95% CI 0.56 to 0.84), severe wheeze (OR = 0.59, 95% CI 0.40 to 0.85), nocturnal cough (OR = 0.73, 95% CI 0.65 to 0.83), chronic cough (OR = 0.75, 95% CI 0.65 to 0.88), and non-coryzal rhinitis (OR = 0.72, 95% CI 0.63 to 0.83). In the follow up study fruit intake recorded at baseline was a strong and independent predictor of all symptoms investigated except non-coryzal rhinitis. In most cases the protective effect was evident even among children whose intake of fruit was only 1-2 times per week and no clear dose-response relationship was found. The effect was stronger (although not significantly so (p = 0.13)) in subjects with a history of asthma; those eating fresh fruit at least once a week experienced a lower one year occurrence of wheeze (29. 3%) than those eating fruit less than once per week (47.1%) (OR = 0. 46, 95% CI 0.27 to 0.81). CONCLUSIONS: Although the effect of other dietary components cannot be excluded, it is concluded that the consumption of fruit rich in vitamin C, even at a low level of intake, may reduce wheezing symptoms in childhood, especially among already susceptible individuals.     

Wheeze, asthma diagnosis and medication use: a national adult survey in a developing country

BACKGROUND: As relatively little is known about adult wheeze and asthma in developing countries, this study aimed to determine the predictors of wheeze, asthma diagnosis, and current treatment in a national survey of South African adults. METHODS: A stratified national probability sample of households was drawn and all adults (>14 years) in the selected households were interviewed. Outcomes of interest were recent wheeze, asthma diagnosis, and current use of asthma medication. Predictors of interest were sex, age, household asset index, education, racial group, urban residence, medical insurance, domestic exposure to smoky fuels, occupational exposure, smoking, body mass index, and past tuberculosis. RESULTS: A total of 5671 men and 8155 women were studied. Although recent wheeze was reported by 14.4% of men and 17.6% of women and asthma diagnosis by 3.7% of men and 3.8% of women, women were less likely than men to be on current treatment (OR 0.6; 95% confidence interval (CI) 0.5 to 0.8). A history of tuberculosis was an independent predictor of both recent wheeze (OR 3.4; 95% CI 2.5 to 4.7) and asthma diagnosis (OR 2.2; 95% CI 1.5 to 3.2), as was occupational exposure (wheeze: OR 1.8; 95% CI 1.5 to 2.0; asthma diagnosis: OR 1.9; 95% CI 1.4 to 2.4). Smoking was associated with wheeze but not asthma diagnosis. Obesity showed an association with wheeze only in younger women. Both wheeze and asthma diagnosis were more prevalent in those with less education but had no association with the asset index. Independently, having medical insurance was associated with a higher prevalence of diagnosis. CONCLUSIONS: Some of the findings may be to due to reporting bias and heterogeneity of the categories wheeze and asthma diagnosis, which may overlap with post tuberculous airways obstruction and chronic obstructive pulmonary disease due to smoking and occupational exposures. The results underline the importance of controlling tuberculosis and occupational exposures as well as smoking in reducing chronic respiratory morbidity. Validation of the asthma questionnaire in this setting and research into the pathophysiology of post tuberculous airways obstruction are also needed.     

Diagnostic and treatment behaviour in children with chronic respiratory symptoms: relationship with socioeconomic factors

BACKGROUND: The prevalence and severity of asthma is believed to increase with increasing socioeconomic deprivation. The relationship between asthma diagnosis, symptoms, diagnostic accuracy, and socioeconomic deprivation as determined by Townsend scores was determined in Sheffield schoolchildren. METHODS: All 6021 schoolchildren aged 8-9 years in one school year in Sheffield were given a parent respondent survey based on International Survey of Asthma and Allergies in Childhood (ISAAC) questions. RESULTS: 5011/6021 (83.2%) questionnaires were returned. Postcode data were available in 4131 replies (82.4%) and were used to assign a composite deprivation score (Townsend score). Scores were divided into five quintiles, with group 1 being least and group 5 being most deprived. A positive trend was observed from group 1 to group 5 for the prevalence of wheeze in the previous 12 months, wheeze attacks >or=4/year, nocturnal wheeze and cough (all p<0.001), cough and/or wheeze "most times" with exertion (p<0.03), current asthma (p<0.001), and significant asthma symptoms (p<0.001). No significant trend was observed for lifetime wheeze or attacks of speech limiting wheeze. There were no significant trends in the prevalence of current asthmatic children without significant symptoms (overdiagnosis) or children with significant asthma symptoms but no current asthma diagnosis (underdiagnosis) across the social groups. There was a significant negative trend in the ratio of asthma medication to asthma diagnosis from least to most deprived groups (p<0.001). CONCLUSIONS: Asthma morbidity and severity increase according to the level of socioeconomic deprivation. This may be due to differences in environment, asthma management, and/or symptom reporting. Diagnostic accuracy does not vary significantly across deprivation groups but children living in areas of least deprivation and taking asthma medication are less likely to be labelled as having asthma, suggesting diagnostic labelling bias.     

Nutrition and respiratory health in children in six Central and Eastern European countries

BACKGROUND: The results of studies on the effect of nutrition on respiratory diseases are inconsistent. The role of nutrition in children's respiratory health was therefore analysed within the cross sectional Central European Study on Air Pollution and Respiratory Health (CESAR). METHOD: A total of 20 271 children aged 7-11 were surveyed in six European countries. Respiratory health and food intake were assessed using questionnaires. Associations between four symptoms and nutritional factors were evaluated using logistic regression, controlling for area plus other potential confounders. RESULTS: All symptoms showed initial associations with nutritional factors. Low consumption of fish and of summer and winter fruit were the most consistent predictors. In a fully adjusted model low fish intake remained a significant independent predictor of persistent cough (OR=1.18; 95% CI 1.04 to 1.34), wheeze ever (OR=1.14; 95% CI 1.03 to 1.25) and current wheeze (OR=1.21; 95% CI 1.06 to 1.39) and a weaker predictor of winter cough (OR=1.10; 95% CI 0.99 to 1.23). Low summer fruit intake was a predictor of winter cough (OR=1.40; 95% CI 1.10 to 1.79) and persistent cough (OR=1.35; 95% CI 1.01 to 1.82). Low winter fruit intake was associated with winter cough (OR=1.28; 95% CI 1.09 to 1.51). Associations between symptoms and vegetable intake were inconsistent. Low summer intake was significantly associated with winter cough (OR=1.23; 95% CI 1.03 to 1.47) but, overall, winter intake had inverse associations with both coughs. Associations between winter vegetable intake and wheeze varied considerably between countries. CONCLUSION: A number of associations were found between respiratory symptoms and low intake of fish, fruit and vegetables in children. Low fish intake was the most consistent predictor of poor respiratory health. Fruit and vegetable intake showed stronger associations with cough than with wheeze.     

Prevalence of atopy, asthma symptoms and diagnosis, and the management of asthma: comparison of an affluent and a non-affluent country

BACKGROUND: The prevalence of childhood asthma and of atopy varies widely between countries. However, few studies have compared the pattern of diagnosis and management of asthma, or the role of atopy in predisposing to asthma between a less affluent country and a more affluent country. The aim of this study was to compare the prevalence of symptoms, diagnosis, and management of asthma, and the prevalence of atopy as measured by skin prick tests in Nigeria and Australia using a standardised methodology. METHODS: Respiratory history was collected using a validated questionnaire administered to parents, and atopy was measured with skin prick tests in 654 Australian and 566 Nigerian children aged 8-11 years (70% consent rate in Australia, 60% in Nigeria). RESULTS: Wheeze and persistent cough were less prevalent in Nigeria (10.2% and 5.1%, respectively) than in Australia (21.9% and 9.6%, respectively), caused less morbidity, and were less likely to be labelled or treated as asthma than in Australia. There was no significant difference in the overall prevalence of atopy between the two countries (Australia 32. 5%, Nigeria 28.2%). Atopy was a strong risk for wheeze in both countries (odds ratio (OR) 3.4 (95% CI 2.3 to 5.1) in Australia, 1.8 (95% CI 1.0 to 3.3) in Nigeria), especially atopy to house dust mites (OR 3.1 (95% CI 2.1 to 4.7) in Australia, 2.4 (95% CI 1.3 to 4. 3) in Nigeria). CONCLUSION: Although there was a similar prevalence of atopy in both countries, Australian children had a higher prevalence of asthma symptoms. Further studies are needed to determine why atopic children in Australia are more at risk of developing asthma. Such studies will have important implications for the prevention of asthma.     

Frequent use of chemical household products is associated with persistent wheezing in pre-school age children

BACKGROUND: In the UK and other developed countries the prevalence of asthma symptoms has increased in recent years. This is likely to be the result of increased exposure to environmental factors. A study was undertaken to investigate the association between maternal use of chemical based products in the prenatal period and patterns of wheeze in early childhood. METHODS: In the population based Avon Longitudinal Study of Parents and Children (ALSPAC), the frequency of use of 11 chemical based domestic products was determined from questionnaires completed by women during pregnancy and a total chemical burden (TCB) score was derived. Four mutually exclusive wheezing patterns were defined for the period from birth to 42 months based on parental questionnaire responses (never wheezed, transient early wheeze, persistent wheeze, and late onset wheeze). Multinomial logistic regression models were used to assess the relationship between these wheezing outcomes and TCB exposure while accounting for numerous potential confounding variables. Complete data for analysis was available for 7019 of 13, 971 (50%) children. RESULTS: The mean (SD) TCB score was 9.4 (4.1), range 0-30. Increased use of domestic chemical based products was associated with persistent wheezing during early childhood (adjusted odds ratio (OR) per unit increase of TCB 1.06 (95% confidence interval (CI) 1.03 to 1.09)) but not with transient early wheeze or late onset wheeze. Children whose mothers had high TCB scores (>90th centile) were more than twice as likely to wheeze persistently throughout early childhood than children whose mothers had a low TCB score (<10th centile) (adjusted OR 2.3 (95% CI 1.2 to 4.4)). CONCLUSION: These findings suggest that frequent use of chemical based products in the prenatal period is associated with persistent wheezing in young children. Follow up of this cohort is underway to determine whether TCB is associated with wheezing, asthma, and atopy at later stages in childhood.     

Increasing prevalence of asthma diagnosis and symptoms in children is confined to mild symptoms

BACKGROUND: The prevalence of childhood asthma is increasing but few studies have investigated trends in asthma severity. We investigated trends in asthma diagnosis and symptom morbidity between an eight year time period in a paired prevalence study. METHODS: All children in one single school year aged 8-9 years in the city of Sheffield were given a parent respondent questionnaire in 1991 and 1999 based on questions from the International Survey of Asthma and Allergy in Children (ISAAC). Data were obtained regarding the prevalence of asthma and wheeze and current (12 month) prevalences of wheeze attacks, speech limiting wheeze, nocturnal cough and wheeze, and exertional symptoms. RESULTS: The response rates in 1991 and 1999 were 4580/5321 (85.3%) and 5011/6021 (83.2%), respectively. There were significant increases between the two surveys in the prevalence of asthma ever (19.9% v 29.7%, mean difference 11.9%, 95% confidence interval (CI) 10.16 to 13.57, p<0.001), current asthma (10.3% v 13.0%, mean difference 2.7%, 95% CI 1.44 to 4.03, p<0.001), wheeze ever (30.3% v 35.8%, mean difference 5.7%, 95% CI 3.76 to 7.56, p<0.001), wheeze in the previous 12 months (17.0% v 19.4%, mean difference 2.5, 95% CI 0.95 to 4.07, p<0.01), and reporting of medication use (16.9% v 20%, mean difference 3.0%, 95% CI 1.46 to 4.62, p<0.001). There were also significant increases in reported hayfever and eczema diagnoses. CONCLUSIONS: Diagnostic labelling of asthma and lifetime prevalence of wheeze has increased. The current 12 month point prevalence of wheeze has increased but this is confined to occasional symptoms. The increased medication rate may be responsible for the static prevalence of severe asthma symptoms. The significant proportion of children receiving medication but reporting no asthma symptoms identified from our 1999 survey suggests that some children are being inappropriately treated or overtreated.     

Trends in the prevalence of asthma in Scottish and English primary school children 1982-92.

BACKGROUND--Some doubts exist as to whether the increase in the prevalence of asthma is real or an artefact. The 10 year trend of asthma up to 1993 in England and Scotland was therefore assessed. METHODS--Information on asthma and bronchitis attacks, occasional wheeze, and persistent wheeze in the last 12 months, was obtained using a self administered questionnaire completed by the parents. Exactly the same questions were asked in 14 study areas in Scotland and 22 study areas in England in 1982 or 1983 and in 1992 or 1993 in 5-11 year old children. RESULTS--The numbers of children with data for all respiratory illness were 5556 (85.2%) and 5801 (87.1%) in England and 3748 (90.4%) and 3738 (90.4%) in Scotland in 1982 and 1992, respectively. There was a significant increase in asthma attacks (approximately three times more in 1992 than in 1982) and occasional wheeze (30-60% more in 1992 than in 1982) in both sexes in England and Scotland. Persistent wheeze also increased in both countries, but the increase was significant only in England (30-40% more in 1992 than in 1982). CONCLUSIONS--The study coincides with others that suggest that the increased prevalence of asthma may be due, in part, to changes in diagnostic behaviour. However, the continuing increase of persistent wheeze in the total sample suggests that part of the increase is real. There was no difference in the increase of persistent wheeze between Scotland and England, but the trend was only significant in England.     

Effect of dampness at home in childhood on bronchial hyperreactivity in adolescence

BACKGROUND: Relatively little is known about risk factors for the persistence of asthma and respiratory symptoms from childhood into adolescence, and few studies have included objective measurements to assess outcomes and exposure. METHODS: From a large cross sectional study of all 4th grade school children in Munich (mean age 10.2 years), 234 children (5%) with active asthma were identified. Of these, 155 (66%) were reinvestigated with lung function measurements and bronchial provocation three years later (mean age 13.5 years). RESULTS: At follow up 35.5% still had active asthma. Risk factors for persisting asthma symptoms in adolescence were more severe asthma (OR 4.94; CI 1.65 to 14.76; p = 0.004) or allergic triggers (OR 3.54; CI 1.41 to 8.92; p = 0.007) in childhood. Dampness was associated with increased night time wheeze and shortness of breath but not with persisting asthma. Risk factors for bronchial hyperreactivity in adolescence were bronchial hyperreactivity in childhood (p = 0.004), symptoms triggered by allergen exposure (OR 5.47; CI 1.91 to 25.20; p = 0.029), and damp housing conditions (OR 16.14; CI 3.53 to 73.73; p < 0.001). In a subgroup in whom house dust mite antigen levels in the bed were measured (70% of the sample), higher mite antigen levels were associated with bronchial hyperreactivity (OR per quartile of mite antigen 2.30; CI 1.03 to 5.12; p = 0.042). Mite antigen levels were also significantly correlated with dampness (p = 0.05). However, the effect of dampness on bronchial hyperreactivity remained significant when adjusting for mite allergen levels (OR 5.77; CI 1.17 to 28.44; p = 0.031). CONCLUSION: Dampness at home is a significant risk factor for the persistence of bronchial hyperreactivity and respiratory symptoms in children with asthma. This risk is only partly explained by exposure to house dust mite antigen.     

Factors influencing the relation of infant feeding to asthma and recurrent wheeze in childhood

BACKGROUND: The relationship between infant feeding and childhood asthma is controversial. This study tested the hypothesis that the relation between breast feeding and childhood asthma is altered by the presence of maternal asthma. METHODS: Healthy non-selected newborn infants (n = 1246) were enrolled at birth. Asthma was defined as a physician diagnosis of asthma plus asthma symptoms reported on > or = 2 questionnaires at 6, 9, 11 or 13 years. Recurrent wheeze (> or = 4 episodes in the past year) was reported by questionnaire at seven ages in the first 13 years of life. Duration of exclusive breast feeding was based on prospective physician reports or parental questionnaires completed at 18 months. Atopy was assessed by skin test responses at the age of 6 years. RESULTS: The relationship between breast feeding, asthma, and wheeze differed with the presence or absence of maternal asthma and atopy in the child. After adjusting for confounders, children with asthmatic mothers were significantly more likely to have asthma if they had been exclusively breast fed (OR 8.7, 95% CI 3.4 to 22.2). This relationship was only evident for atopic children and persisted after adjusting for confounders. In contrast, the relation between recurrent wheeze and breast feeding was age dependent. In the first 2 years of life exclusive breast feeding was associated with significantly lower rates of recurrent wheeze (OR 0.45, 95% CI 0.2 to 0.9), regardless of the presence or absence of maternal asthma or atopy in the child. Beginning at the age of 6 years, exclusive breast feeding was unrelated to prevalence of recurrent wheeze, except for children with asthmatic mothers in whom it was associated with a higher odds ratio for wheeze (OR 5.7, 95% CI 2.3 to 14.1), especially if the child was atopic. CONCLUSION: The relationship between breast feeding and asthma or recurrent wheeze varies with the age of the child and the presence or absence of maternal asthma and atopy in the child. While associated with protection against recurrent wheeze early in life, breast feeding is associated with an increased risk of asthma and recurrent wheeze beginning at the age of 6 years, but only for atopic children with asthmatic mothers.     

Risk factors for onset and remission of atopy, wheeze, and airway hyperresponsiveness

BACKGROUND: Although many children with asthma may have a remission as they grow and other children who did not have asthma may develop asthma in adult life, knowledge about the factors that influence the onset and prognosis of asthma during adolescence and young adulthood is very limited. METHODS: A cohort of 8-10 year old children (n=718) living in Belmont, New South Wales, Australia were surveyed six times at 2 yearly intervals from 1982 to 1992, and then again 5 years later in 1997. From this cohort, 498 subjects had between three and seven assessments and were included in the analysis. Atopy, airway hyperresponsiveness (AHR), and wheeze in the last 12 months were measured at each survey. Late onset, remission, and persistence were defined based on characteristics at the initial survey and the changes in characteristics at the follow up surveys. RESULTS: The proportion of subjects with late onset atopy (13.7%) and wheeze (12.4%) was greater than the proportion with remission of atopy (3.2%) and wheeze (5.6%). Having atopy at age 8-12 years (OR 2.8, 95% CI 1.5 to 5.1) and having a parental history of asthma (OR 2.0, 95% CI 1.02 to 4.13) were significant risk factors for the onset of wheeze. Having AHR at age 8-12 years was a significant risk factor for the persistence of wheeze (OR 4.3, 95% CI 1.3 to 15.0). Female sex (OR 1.9, 95% CI 1.01 to 3.60) was a significant risk factor for late onset AHR whereas male sex (OR 1.9, 95% CI 1.1 to 2.8) was a significant risk factor for late onset atopy. CONCLUSIONS: The onset of AHR is uncommon during adolescence, but the risk of acquiring atopy and recent wheeze for the first time continues during this period. Atopy, particularly present at the age of 8-10 years, predicts the subsequent onset of wheeze.     

The early origins hypothesis with an emphasis on growth rate in the first year of life and asthma: a prospective study in Chile

BACKGROUND: There is uncertainty about the impact of the programming hypothesis in terms of nutritional status at birth, rate of growth in the first year of life, length of gestation, breast feeding, and episodes of illness on asthma. An analysis was therefore carried out to test this hypothesis. METHODS: Data were collected on 1232 children born between 1974 and 1978 in a semi-rural area of Chile. Measurements at birth and growth in the first year of life were obtained from a birth registry and clinical notes. Information on asthma was collected using the European Community Respiratory Health Survey questionnaire. Sensitisation to eight allergens and bronchial hyperresponsiveness (BHR) to methacholine were determined. All other information was obtained using a questionnaire. Polytomous logistic analyses were carried out to explore the association of factors at birth and during the first year of life with asthma symptoms, atopy, and BHR. RESULTS: Weight and length gain in the first year were positively associated with wheeze (odds ratio (OR) 1.004, 95% CI 1.001 to 1.007 and OR 1.11, 95% CI 0.98 to 1.25, respectively). A higher body mass index (BMI) at birth was protective in subjects reporting both wheeze and waking with breathlessness (OR 0.54, 95% CI 0.35 to 0.84). Length rate in tertiles divided by length at birth in tertiles was related to asthma symptoms (OR 1.68, 95% CI 1.19 to 2.37). Most other assessments were not associated with asthma. CONCLUSION: These results show promising but inconclusive evidence that a rapid rate of growth in length, especially in newborn infants of low length, might be involved in the aetiology of asthma.     

Hormone replacement therapy, body mass index and asthma in perimenopausal women: a cross sectional survey

BACKGROUND: Hormone replacement therapy (HRT) and obesity both appear to increase the risk of asthma. A study was undertaken to investigate the association of HRT with asthma and hay fever in a population of perimenopausal women, focusing on a possible interaction with body mass index (BMI). METHODS: A postal questionnaire was sent to population based samples in Denmark, Estonia, Iceland, Norway, and Sweden in 1999-2001, and 8588 women aged 25-54 years responded (77%). Pregnant women, women using oral contraceptives, and women <46 years were excluded. Analyses included 2206 women aged 46-54 years of which 884 were menopausal and 540 used HRT. Stratified analyses by BMI in tertiles were performed. RESULTS: HRT was associated with an increased risk for asthma (OR 1.57 (95% CI 1.07 to 2.30)), wheeze (OR 1.60 (95% CI 1.22 to 2.10)), and hay fever (OR 1.48 (95% CI 1.15 to 1.90)). The associations with asthma and wheeze were significantly stronger among women with BMI in the lower tertile (asthma OR 2.41 (95% CI 1.21 to 4.77); wheeze OR 2.04 (95% CI 1.23 to 3.36)) than in heavier women (asthma: p(interaction) = 0.030; wheeze: p(interaction) = 0.042). Increasing BMI was associated with more asthma (OR 1.08 (95% CI 1.05 to 1.12) per kg/m2). This effect was only found in women not taking HRT (OR 1.10 (95% CI 1.05 to 1.14) per kg/m2); no such association was detected in HRT users (OR 1.00 (95% CI 0.92 to 1.08) per kg/m2) (p(interaction) = 0.046). Menopause was not significantly associated with asthma, wheeze, or hay fever. CONCLUSIONS: In perimenopausal women there is an interaction between HRT and BMI in the effects on asthma. Lean women who were HRT users had as high a risk for asthma as overweight women not taking HRT. It is suggested that HRT and overweight increase the risk of asthma through partly common pathways.     

Asymptomatic bronchial hyperresponsiveness to exercise in childhood and the development of asthma related symptoms in young adulthood: the Odense Schoolchild Study

BACKGROUND: Exercise testing may be of value in identifying a group of children at high risk of subsequently developing respiratory symptoms. As few longitudinal studies have investigated this issue, the bronchial hyperresponsiveness to exercise in asymptomatic children was evaluated as a risk factor for developing asthma related symptoms in young adulthood. METHODS: A community based sample of 1369 schoolchildren, first investigated in 1985 at a mean age of 9.7 years, was followed up after a mean of 10.5 years. Nine hundred and twenty children (67%) were asymptomatic in childhood and 777 (84.9%) of these were re-investigated at follow up. At the first examination a maximum progressive exercise test on a bicycle ergometer was used to induce airway narrowing. The forced expiratory volume in one second (FEV1) after exercise was considered abnormal if the percentage fall in FEV1 was more than 5% of the highest fall in the reference subjects characterised by having no previous history of asthma or asthma related symptoms. The threshold for a positive test was 8.6% of pre-exercise FEV1. RESULTS: One hundred and three subjects (13%) had wheeze within the last year at follow up and, of these, nine (9%) had been hyperresponsive to exercise in 1985. One hundred and seventy subjects (22%) had non-infectious cough within the previous year, 11 of whom (6%) had been hyperresponsive to exercise in 1985. Multiple regression analysis showed that subjects with hyperresponsiveness to exercise had an increased risk of developing wheeze compared with subjects with a normal response to exercise when the fall in FEV1 after exercise was included as a variable (threshold odds ratio (OR) 2.3 (95% CI 1.1 to 5.5)). The trend was not significant when exercise induced bronchospasm was included as a continuous variable (OR 1.02 (95% CI 0.97 to 1.06)). CONCLUSIONS: Asymptomatic children who are hyperresponsive to exercise are at increased risk of developing new symptoms related to wheezing but the predictive value of exercise testing for individuals is low.     

Glutathione S transferase deficiency and passive smoking increase childhood asthma

BACKGROUND: It has been suggested that the genetically determined deficiency of glutathione S transferase (GST) enzymes involved in the detoxification of environmental tobacco smoke (ETS) components may contribute to the development of asthma. METHODS: A large population of German schoolchildren (n = 3054) was genotyped for deficiencies of the GST isoforms M1 and T1. The association between GSTM1 and GSTT1 genotypes and asthma as well as atopy was investigated with respect to current and in utero ETS exposure. RESULTS: In children lacking the GSTM1 allele who were exposed to current ETS the risk for current asthma (OR 5.5, 95% CI 1.6 to 18.6) and asthma symptoms such as wheeze ever (OR 2.8, 95% CI 1.3 to 6.0), current wheezing (OR 4.7, 95% CI 1.8 to 12.6) and shortness of breath (OR 8.9, 95% CI 2.1 to 38.4) was higher than in GSTM1 positive individuals without ETS exposure. Hints of an interaction between ETS exposure and GSTM1 deficiency were identified. In utero smoke exposure in GSTT1 deficient children was associated with significant decrements in lung function compared with GSTT1 positive children not exposed to ETS. CONCLUSIONS: GSTM1 and GSTT1 deficiency may increase the adverse health effects of in utero and current smoke exposure.     

Can the increase in body mass index explain the rising trend in asthma in children?

BACKGROUND: The reported association between asthma and obesity and the documented rise in each over time have led to suggestions that rising obesity might explain the increase in the prevalence of asthma. Trends in both in British children participating in the National Study of Health and Growth were marked from 1982 to 1994. METHODS: Odd ratios for trends in asthma and symptoms in 8 and 9 year old children were calculated with and without adjustment for body mass index (BMI). RESULTS: In a representative sample of white children the odds ratio per year for asthma was 1.09 (95% CI 1.07 to 1.11) before and after adjustment for BMI for boys and 1.09 (95% CI 1.07 to 1.12) and 1.09 (95% CI 1.05 to 1.12), respectively, for girls. Unadjusted and adjusted odds ratios were also virtually identical for wheeze and "asthma or bronchitis". The lack of effect of adjustment was due to a change in the association between BMI and symptoms with time. CONCLUSIONS: Trends in overweight and obesity do not explain the increase in asthma. The evidence points towards the association between asthma and obesity being of recent origin. This may be explained by obesity being a marker of recent lifestyle differences now associated with both asthma and overweight.