Prevalence and trends in overweight and obesity in three cross sectional studies of British Children, 1974-94

OBJECTIVES

To report trends in overweight and obesity, defined by new internationally agreed cut-off points, in children in the United Kingdom.

DESIGN

Three independent cross sectional surveys.

SETTING

Primary schools in England and Scotland.

PARTICIPANTS

10 414 boys and 9737 girls in England and 5385 boys and 5219 girls in Scotland aged 4 to 11 years.

MAIN OUTCOME MEASURES

Prevalence and change in prevalence of overweight and obesity, as defined by the international obesity task force, in 1974, 1984, and 1994, for each sex and country.

RESULTS

Little change was found in the prevalence of overweight or obesity from 1974 to 1984. From 1984 to 1994 overweight increased from 5.4% to 9.0% in English boys (increase 3. 6%, 95% confidence interval 2.3% to 5.0%) and from 6.4% to 10.0% in Scottish boys (3.6%, 1.9% to 5.4%). Values for girls were 9.3% to 13. 5% (4.1%, 2.4% to 5.9%) and 10.4% to 15.8% (5.4%, 3.2% to 7.6%), respectively. The prevalence of obesity increased correspondingly, reaching 1.7% (English boys), 2.1% (Scottish boys), 2.6% (English girls), and 3.2% (Scottish girls).

CONCLUSION

These results form a base from which trends can be monitored. The rising trends are likely to be reflected in increases in adult obesity and associated morbidity.

A simple method for converting an odds ratio to effect size for use in meta-analysis

A systematic review may encompass both odds ratios and mean differences in continuous outcomes. A separate meta-analysis of each type of outcome results in loss of information and may be misleading. It is shown that a ln(odds ratio) can be converted to effect size by dividing by 1.81. The validity of effect size, the estimate of interest divided by the residual standard deviation, depends on comparable variation across studies. If researchers routinely report residual standard deviation, any subsequent review can combine both odds ratios and effect sizes in a single meta-analysis when this is justified.

Paracetamol sales and atopic disease in children and adults: an ecological analysis

The authors recently observed that frequent paracetamol use was positively associated with asthma and rhinitis in young adults. Therefore, an ecological analysis was performed to measure international associations between paracetamol sales and atopic disease prevalences in children and adults. Published data from the International Study of Asthma and Allergies in Childhood (ISAAC) on the prevalence of four atopic symptoms in 13-14-yr-olds (112 centres) and 67-yr-olds (66 centres) in 1994/1995, and European Community Respiratory Health Survey (ECRHS) data on the prevalence of asthma symptoms, diagnosed asthma and rhinitis (44 centres), prevalence of atopy, mean bronchial responsiveness and mean total immunoglobulin E levels (34 centres) in young adults in 1991/1992, were used. Their associations with national 1994/1995 per capita paracetamol sales were measured using linear regression. Paracetamol sales were high in English-speaking countries, and were positively associated with asthma symptoms, eczema and allergic rhinoconjunctivitis in 13-14-yr-olds, and with wheeze, diagnosed asthma, rhinitis and bronchial responsiveness in adults. The prevalence of wheeze increased by 0.52% in 13-14-yr-olds and by 0.26% in adults (p<0.0005) for each gram increase in per capita paracetamol sales. These ecological findings require cautious interpretation, but raise the possibility that variation in paracetamol usage may explain some of the variation in atopic disease prevalence between countries.

A double blind, randomized, controlled clinical trial to assess the efficacy of a new coal tar preparation (Exorex) in the treatment of chronic, plaque type psoriasis

Exorex is a new topical formulation for the treatment of psoriasis; it contains 1% coal tar and a synthetic analogue resembling components identified in banana skin (a complex of esterified essential fatty acids). To determine whether the esterified essential fatty acid complex confers any therapeutic advantage over coal tar alone, patients with chronic plaque psoriasis (n = 20) were entered into a double-blind, randomized, right/left comparison of Exorex, and Exorex without the essential fatty acid component (known hereafter as coal tar control) for 8 weeks. Target plaques were scored (0-4) for erythema, desquamation and infiltration at day 0 and at 2 week intervals throughout the study. No significant differences were detected between Exorex and coal tar control with respect to changes in the summed scores at baseline and following 8 weeks of treatment (mean difference in summed score changes from baseline between Exorex and coal tar control 0.2, 95% confidence interval - 0.44 to 0.84; P = 0.52) or in the area under the response-time curve (P = 0.16). Mean percentage improvement in summed scores of target plaques were 53.9% (SE = 4%) and 56.1% (SE = 4.9%) for Exorex and coal tar control, respectively. Results suggest that the complex of esterified essential fatty acids is not exerting any clinically important therapeutic effect in the treatment of chronic plaque psoriasis.

Comparison of asthma prevalence in the ISAAC and the ECRHS. ISAAC Steering Committee and the European Community Respiratory Health Survey. International Study of Asthma and Allergies in Childhood

International and regional prevalence comparisons are required to test and generate hypotheses regarding the causes of increasing asthma prevalence in various age groups worldwide. The International Study of Asthma and Allergies in Childhood (ISAAC) is the first such study in children and the European Community Respiratory Health Survey (ECRHS) is the first such study in adults. Therefore, a comparison of the findings of these two surveys was conducted, for the 17 countries in which both surveys were undertaken. There was a strong correlation between the ISAAC and ECRHS prevalence data, with 64% of the variation at the country level, and 74% of the variation at the centre level, in the prevalence of "wheeze in the last 12 months" in the ECRHS phase I data being explained by the variation in the ISAAC phase I data. There was also generally good agreement in the international patterns observed in the two surveys for self-reported asthma (74% of country level and 36% of centre level variation explained), self-reported asthma before age 14 yrs (64 and 26%), hay fever (61 and 73%) and eczema (41 and 50%). Thus although there were differences in the absolute levels of prevalence observed in the two surveys, there is good overall agreement between the International Study of Asthma and Allergies in Childhood and European Community Respiratory Health Survey study findings with regard to international prevalence patterns. These findings, therefore, add support to the validity of the two studies, which provide a new picture of global patterns of asthma prevalence from child- to adulthood, and identify some of the key phenomena which future research must address.

Factors associated with preterm births in southeast Brazil: a comparison of two birth cohorts born 15 years apart

An increase in preterm deliveries in Ribeirão Preto stimulated an analysis of possible explanatory factors. Two cohorts of singleton livebirths were studied, the first based on 6746 births in 1978-9 and the second based on 2846 births in 1994. A logistic regression was carried out to assess the association of preterm birth with several sociodemographic, behavioural and clinical variables, including year of survey. Delivery in private settings compared with a public setting, maternal age of < or = 17 compared with any other age group, and mothers who had had previous abortions and previous stillbirths were associated with greater rates of preterm birth. Although there was an increase in preterm birth rates regardless of mode of delivery, the increase was greater in the caesarean section group than in the vaginal delivery group. Over the study period, deliveries in private hospitals and caesarean section operations increased markedly (from 4% to 36% and from 30% to 51% respectively). Caesarean section may be the main contributor to the increase of preterm birth rate in this study. It is essential to ensure that health-care staff, especially those in private facilities, are properly educated and audited.

Role of current and childhood exposure to cat and atopic sensitization. European Community Respiratory Health Survey

BACKGROUND

Clinical and population studies have shown that exposure and sensitization to allergens derived from furred pets, particularly cats, represent an important risk factor of allergic respiratory disease and also a significant risk factor for asthma.

OBJECTIVE

In the framework of the multicenter European Community Respiratory Health Survey an analysis of the association of current and childhood exposure to cat with atopic sensitization to cat was conducted.

METHODS

This study included cross-sectional data from 35 centers representing 16 countries. Altogether, 18,097 subjects were included, of whom 13,509 (75%) provided a blood sample for the measurement of specific IgE. Exposure data and data for potential confounders were extracted from an interviewer-led questionnaire.

RESULTS

The prevalence of sensitization to cat (serum specific IgE >0.35 kU/L) was 9%. Among those who did not report allergic symptoms in the presence of pets or house dust, those who owned cats were significantly more likely to be sensitized to cats than were those who did not (odds ratio [95% confidence interval] 1.57 [1.20-2.06]. Childhood exposure to pets including cats was associated with lower sensitization to cats in adulthood, particularly among those with a positive family history of atopy (odds ratio [95% confidence interval] 0.68 [0.51-0.93]. Positive correlations were found between the community prevalence of cat and the prevalences of sensitization to cat, respiratory symptoms, physician-diagnosed asthma, and current asthma medication.

CONCLUSIONS

Current cat ownership represents a significant risk for sensitization to cat if cats are allowed indoors. Our results support the hypothesis that childhood exposure to pets, including cats, might modulate immunologic mechanisms and reduce sensitization to cat in adulthood. The significant correlation found between the community prevalence of cat ownership and community prevalence of specific sensitization to cat represents the first documentation of such a relationship.

The association of smoking with sensitization to common environmental allergens: results from the European Community Respiratory Health Survey

BACKGROUND

Smoking is a risk factor for sensitization to some occupational allergens, but its association with sensitization to common environmental allergens remains unclear.

OBJECTIVE

We sought to determine the association of smoking with total IgE levels and with sensitization to 3 common environmental allergens in data from the European Community Respiratory Health Survey.

METHODS

A detailed smoking history and blood sample for determination of serum total IgE and specific IgE levels to house dust mite, grass, and cat allergens was obtained from 13,002 randomly selected young adults living in the areas served by 34 centers in 14 countries. Associations with smoking status and amount smoked were determined. Because there was evidence of heterogeneity between centers in the association of age, sex, and smoking with sensitization, odds ratios (ORs) were determined for each center and combined by using random-effects meta-analysis.

RESULTS

Compared with lifetime nonsmokers, current smokers were at an increased risk of sensitization to house dust mite allergen (OR, 1.13; 95% confidence interval [CI], 1.02-1.26) but a decreased risk of sensitization to grass (OR, 0.76; 95% CI, 0.67-0.88) and cat allergens (OR, 0.69; 95% CI, 0.59-0.80). Exclusion of those with symptoms suggestive of current asthma strengthened the association of smoking with sensitization to house dust mite allergen (OR, 1.29; 95% CI, 1.11-1. 50). The geometric mean total IgE level was higher in smokers and was higher among those who currently smoked the most compared with those who smoked less than 5 cigarettes per day.

CONCLUSION

The association between smoking and sensitization to common environmental allergens is different for different allergens.

Sensitization to individual allergens and bronchial responsiveness in the ECRHS. European Community Respiratory Health Survey

Little is known about the relation of bronchial responsiveness (BHR) to sensitization to individual allergens, or its variation between countries. Data were obtained for BHR, specific immunoglobulin E and confounding variables from 11,215 subjects, aged 20-44 yrs at the start of the European Community Respiratory Health Survey, in 34 centres in 15 countries. The relation of BHR to sensitization to cat, house dust mite, timothy grass and Cladosporium was estimated by means of multiple regression for each centre, and combined across centres by random effects meta-analysis, controlling for baseline lung function, height, sex, season of testing, age, smoking and age/sex and age/smoking interactions. BHR was greater, on average, in those sensitized to cat (p=0.023), house dust mite (p<0.001) and timothy grass (p=0.018), but not to Cladosporium (p=0.60), and increased with degree of sensitization (p<0.001). All relations showed heterogeneity between centres, although to a lesser extent in the relation to sensitization to house dust mite. More variation in bronchial responsiveness was explained by sensitization and degree of sensitization to the individual allergens than by atopy defined as any positive test in each centre, but the relative importance of each allergen varied. The use of atopy as a single variable in relation to bronchial hyperresponsiveness may be misleading.

Components of variance and intraclass correlations for the design of community-based surveys and intervention studies: data from the Health Survey for England 1994

The authors estimated components of variance and intraclass correlation coefficients (ICCs) to aid in the design of complex surveys and community intervention studies by analyzing data from the Health Survey for England 1994. This cross-sectional survey of English adults included data on a range of lifestyle risk factors and health outcomes. For the survey, households were sampled in 720 postal code sectors nested within 177 district health authorities and 14 regional health authorities. Study subjects were adults aged 16 years or more. ICCs and components of variance were estimated from a nested random-effects analysis of variance. Results are presented at the district health authority, postal code sector, and household levels. Between-cluster variation was evident at each level of clustering. In these data, ICCs were inversely related to cluster size, but design effects could be substantial when the cluster size was large. Most ICCs were below 0.01 at the district health authority level, and they were mostly below 0.05 at the postal code sector level. At the household level, many ICCs were in the range of 0.0-0.3. These data may provide useful information for the design of epidemiologic studies in which the units sampled or allocated range in size from households to large administrative areas.

Variation in physical fitness between ethnic groups in nine year olds

BACKGROUND

There is little information on cardio-respiratory fitness of children, especially in ethnic minorities in Britain. In this study we assess the associations of social factors, ethnicity, parental health related factors, child's anthropometry, blood pressure and cholesterol measurements with cardio-respiratory fitness.

METHODS

Power output against load at 85% of the maximum heart rate (PWC85%), was measured, using a cycle-ergometer test, in children aged 8-9 years in 22 randomly selected areas in England, 14 in Scotland and in 20 inner city areas in England. The subjects were 317 boys and 310 girls from the English sample, 152 boys and 140 girls from the Scottish sample and 242 boys and 261 girls from the inner city sample.

RESULTS

Short stature (P < 0.001), fatness (P < 0.001), and Indian subcontinent origin (OR = 0.34, 95% CI: 0.16, 0.68 in boys and OR = 0.22, 95% CI: 0.12, 0.40 in girls) were associated with inability to finish the test. In those who finished the test PWC85% was greater in taller children and in those with lower skinfold values (P < 0.001, except height in boys P = 0.017). The PWC85% in those originating in the Indian continent was lower (-0.17 watt/kg, 95% CI :-0.32, -0.01 in boys and -0.29, 95% CI: -0.43, -0.14 in girls) than in white children.

CONCLUSIONS

Shorter and obese children have poorer physical fitness than other children. Physical fitness is lower in children originating in the Indian subcontinent than other British children. This seems to be unrelated to socioeconomic disadvantage. Physical inactivity and lack of cycling skills may explain our findings.

Childhood environment and adult atopy: results from the European Community Respiratory Health Survey

BACKGROUND

Previous literature has indicated that environmental exposures in childhood influence development of atopic sensitization.

OBJECTIVE

We sought to study the association between childhood environment and adult atopy.

METHODS

Thirteen thousand nine hundred thirty-two subjects aged 20 to 44 years from 36 areas in Europe, New Zealand, the United States, and Australia took part in the European Community Respiratory Health Survey, answering interviewer-led questionnaires and providing blood tests for measurement of specific IgE to grass, house dust mite, cat, and Cladosporium allergens.

RESULTS

Atopy was negatively associated with family size (OR = 0. 93; 95% CI = 0.90-0.96 per 1 sib), partly attributable to an independent protective effect of a greater number of brothers (OR = 0.92; 95% CI = 0.89-0.95 per 1 brother). Accounting for total number of siblings, no further influence was detected for number of older or younger siblings. Bedroom sharing was associated with a lower prevalence of atopy, particularly to cat allergen. A protective effect of family size and bedroom sharing could only be detected in subjects reporting no parental allergy (family size, test for interaction P =.012). The presence of a dog in the home in childhood was negatively associated with adult atopy (OR = 0.85, 95% CI = 0. 78-0.92), an effect that remained after adjustment for parental allergy, sibling allergy, and adult pet ownership.

CONCLUSION

Subjects from large families with brothers, shared bedrooms, and dogs in childhood were less often atopic as adults. Our findings are consistent with the hypothesis that infectious agents could inhibit development of atopy during childhood. However, in subjects with a strong genetic predisposition, environmental factors in childhood are possibly of less importance.

Association between asthma and family size between 1977 and 1994

STUDY OBJECTIVES

Several recent reports show a negative association between asthma and family size or birth order, but this association was not detected in data collected between 10 and 30 years ago. This study compared the association between sibship size and asthma in three surveys using the same methodology in 1977, 1985/86, and 1993/94.

DESIGN

Cross sectional comparison of the 1977, 1985/86, and 1993/94 surveys.

SETTINGS

Study areas in England and Scotland.

PARTICIPANTS

Parents of children between 5 to 11 years in England and Scotland were asked about asthma and bronchitis attacks in the last 12 months, and wheeze in their child. Approximately 9000 children participated in each of the surveys.

RESULTS

The overall association between asthma, defined as asthma attacks or wheeze, and total number of siblings was not significant (p = 0.22), but an only child had a higher prevalence of asthma than children with siblings (OR 0.87 95% CI 0.76 to 0.98). The interaction between year of survey and sibship size on asthma was not significant (p = 0.36). There was no association between asthma and birth order. A significant interaction between social class and year of survey on asthma was detected (p = 0.004). In the 1993/94 survey children whose fathers had a semi or unskilled manual occupation had a higher prevalence of asthma (16%) than children whose fathers belonged to other social classes (13%).

CONCLUSIONS

This study provides only marginal support for a change over time of the association between sibship size and asthma. Based on recent reports the nature of the exposure agent that may explain the association remains controversial. This study suggests a disproportionate increase of asthma in lower social classes.

Individual use of antiasthmatic drugs in the European Community Respiratory Health Survey

A previous analysis of drug utilization in the European Community Respiratory Health Survey found that only between 8 and 29% of subjects with asthma-related symptoms were using antiasthmatic medication in the different areas studied. The aim of this analysis was to investigate which variables were related to individual use of antiasthmatic medication in different geographical areas. Thirty-three centres in 14 countries were analysed, in which a total of 16,854 people (52.1% females, mean age 33.8 yrs, range 20-48) underwent a structured interview, measurement of specific immunoglobin E, spirometry and methacholine challenge test. The use of antiasthmatic drugs in individuals was, in most countries, independently related to asthma-related respiratory symptoms, bronchial hyperresponsiveness (BHR) and atopy. In all countries smokers with respiratory symptoms were less likely to be using antiasthmatic drugs than nonsmokers and exsmokers. In four of 14 countries females were significantly more likely to use antiasthmatic medication than males, while age and socioeconomic status were unrelated to medication. The use of inhaled anti-inflammatory drugs was positively related to symptoms, BHR and atopy and negatively related to current smoking. In conclusion, in many countries smokers were less likely to be using antiasthmatic drugs than were nonsmokers with comparable levels of symptoms and bronchial hyperresponsiveness. Age and socioeconomic status were unrelated to medication, while in some countries females were more likely than males to use antiasthmatic medication.

Individual allergens as risk factors for bronchial responsiveness in young adults

BACKGROUND

Bronchial responsiveness is known to be related to atopy, but the relative contribution of sensitisation to individual allergens in the UK, or whether serum total IgE is an independent risk factor, is unknown.

METHODS

A random sample of 1864 men and women aged 20-44 years, drawn from family health service registers in Cambridge, Ipswich and Norwich, was invited to answer a detailed questionnaire, undergo skin prick tests and methacholine bronchial challenge, and provide a serum sample for measurement of total and specific IgE. The relation of bronchial responsiveness to risk factors was studied in 749 subjects (40.2%) with complete data.

RESULTS

Bronchial responsiveness was increased in those sensitised to cat, D pteronyssinus, Timothy grass and Cladosporium, but decreased in subjects also positive to birch allergen. Additional skin prick tests added little information. Serum total IgE was not significantly related after adjustment for specific IgE to the five allergens. Increasing titres of specific IgE to D pteronyssinus were associated with increasing bronchial responsiveness. Specific IgE to Cladosporium had a prevalence of around 3%, but was associated with greatly increased responsiveness. Decreased baseline lung function was related (p < 0.001) to increased responsiveness. There was an interaction between age and smoking status, with lower responsiveness in older non-smokers.

CONCLUSION

Atopy is the most important risk factor for bronchial responsiveness in this age group, but effects are not additive across all allergens. Research in reducing exposure to house dust mite should also address the role of Cladosporium sensitisation and exposure to indoor moulds.

Trends in growth and obesity in ethnic groups in Britain

AIM

To estimate trends in growth for 5 to 11 year old ethnic minority and inner city children and comparative representative samples from 1983 to 1994.

DESIGN

Mixed longitudinal.

SUBJECTS

At each of six surveys, more than 2000 inner city white, 1500 Urdu or Punjabi speaking, 5000 English representative white, 3000 Scottish representative white, and around 1000 Afro-Caribbean, 500 falling to 300 Gujarati speaking, and 260 increasing to 300 other Indian children.

MAIN OUTCOME MEASUREMENTS

Height, weight for height, and triceps skinfold thickness.

RESULTS

Height increased in all inner city groups by approximately 1.5 cm, but group differences were maintained. Trends in triceps skinfold varied, but increased by 4-12% in Indian subcontinent girls. Weight for height increased generally. Inner city white children showed conflicting trends in weight for height and fatness.

CONCLUSIONS

Afro-Caribbean children are maintaining their tall, slim build, but other groups emphasise the diversity of obesity patterns in a multi-ethnic society, with a predominant trend towards greater obesity. Monitoring of these groups should continue.

References values for forced spirometry. Group of the European Community Respiratory Health Survey

The European Coal and Steel Community (ECSC) prediction equations exemplify a significant effort carried out approximately 15 yrs ago to provide uniform standards for lung function testing, but this set of equations has not been properly validated as yet. The present study evaluates the ECSC reference values and four other sets of prediction equations, using spirometric data collected in 12,900 nonasthmatic subjects (43% lifetime nonsmokers and 36% active smokers) aged 20-44 yrs from the European Community Respiratory Health Survey (ECRHS). Standardized spirometric measurements were obtained using a common protocol in 34 centres in 14 countries. For each prediction equation, the prediction deviations (i.e. observed minus predicted value) for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were examined for the whole study population and for each centre. For the age range included, the errors about the ECSC equations showed the most prominent underestimation of both predicted FVC (+355 and +360 mL on average in males and females, respectively) and predicted FEV1 (+211 and +200 mL, respectively) among the five studies examined. As expected, FVC and FEV1 in active smokers from the ECRHS were significantly lower than in lifetime nonsmokers (each p<0.01). We conclude that the present European recommendations on lung function reference values should be reconsidered, but further data for nonsymptomatic subjects above the age of 44 yrs are needed.

Serum cholesterol and haematology at age eight to ten years

The aim of the study was to estimate 95% reference ranges for blood constituents in 9-year-old children. Venepuncture was successful in 753 white children age 8-9 years in 21 areas in England and 5 in Scotland. Agreement with published reference ranges for haematological measurements from undocumented samples was good. The reference ranges were 3.22 to 5.79 mmol/l for serum total cholesterol, 0.9 to 2.1 mmol/l for high density lipoprotein cholesterol, and 13 to 61 micrograms/l for ferritin. The upper limit for total cholesterol is well above the recommended level for adults, with 9.3% of children having a value of 5.2 mmol/l or more. The results provide a scientific basis for ranges previously published for haematological measurements. Documented data should be combined from national studies to provide further reference ranges for routine use.

The association of respiratory symptoms and lung function with the use of gas for cooking. European Community Respiratory Health Survey

The association of respiratory symptoms and lung function with the use of gas for cooking was examined using data collected as part of the European Community Respiratory Health Survey, an international multicentre study. Associations between gas cooking and respiratory symptoms and respiratory function were assessed by logistic and multiple regression models. Tests for interaction were used to examine whether the effect of gas cooking varied between centres and, as there was evidence for this, the average effects were estimated using standard methods for random effects meta-analysis. Data from 5,561 males and 6,029 females living in 23 centres in 11 countries were analysed. There was no significant association found between respiratory symptoms and gas cooking in males. In females the association between some respiratory symptoms and gas cooking varied between centres with an overall positive association with "wheeze in the last 12 months" (odds ratio (OR) 1.24: 95% confidence interval (95% CI) 1.00-1.54) and "wheeze with breathlessness in the last 12 months" (OR 1.33: 95% CI 1.06-1.69). There was no evidence that atopy modified this association. Cooking with gas was associated with airways obstruction in both males and females although the differences failed to reach statistical significance. In some countries the use of gas for cooking is associated with respiratory symptoms suggestive of airways obstruction in females.

The association of respiratory symptoms and lung function with the use of gas for cooking. European Community Respiratory Health Survey

The association of respiratory symptoms and lung function with the use of gas for cooking was examined using data collected as part of the European Community Respiratory Health Survey, an international multicentre study. Associations between gas cooking and respiratory symptoms and respiratory function were assessed by logistic and multiple regression models. Tests for interaction were used to examine whether the effect of gas cooking varied between centres and, as there was evidence for this, the average effects were estimated using standard methods for random effects meta-analysis. Data from 5,561 males and 6,029 females living in 23 centres in 11 countries were analysed. There was no significant association found between respiratory symptoms and gas cooking in males. In females the association between some respiratory symptoms and gas cooking varied between centres with an overall positive association with "wheeze in the last 12 months" (odds ratio (OR) 1.24: 95% confidence interval (95% CI) 1.00-1.54) and "wheeze with breathlessness in the last 12 months" (OR 1.33: 95% CI 1.06-1.69). There was no evidence that atopy modified this association. Cooking with gas was associated with airways obstruction in both males and females although the differences failed to reach statistical significance. In some countries the use of gas for cooking is associated with respiratory symptoms suggestive of airways obstruction in females.

Disturbed sleep: effects of sociocultural factors and illness

To assess the prevalence of sleep disturbance and associated risk factors, sleep patterns were analysed in 14,372 English and Scottish children. Approximately 4% of children aged 5 experienced disturbed sleep more than once a week, but this decreased to 1% from age 9. Less than 25% of the parents with an affected child consulted a doctor. Sleep disturbance was associated with persistent wheezing compared to non-wheezing children (odds ratio 4.42; 95% confidence interval (CI) 3.17 to 6.13), and more frequent in children of Indian subcontinent descent than in white children (odds ratio 2.20; 95% CI 1.34 to 3.60), and in children whose mother reached no more than primary education compared with those with higher education (odds ratio 2.41; 95% CI 1.51 to 3.84). Sociocultural factors associated with ethnicity and respiratory illness are important risk factors for sleeping disorders in childhood.