Variation in bronchial responsiveness in the European Community Respiratory Health Survey (ECRHS)

Attempts to compare bronchial responsiveness between populations have been hampered by between-study differences in the pharmacological agent of provocation, the method of administration and the summary statistic employed. The European Community Respiratory Health Survey used methacholine challenge delivered by Mefar dosimeter according to a standardized protocol used in 35 centres in 16 countries. Data were obtained from 13,161 men and women, aged 20-44 yrs at the start of the study. The dose of methacholine producing a 20% fall in forced expiratory volume in one second (FEV1) (PD20) and the regression coefficient of percentage decline in FEV1 with log dose, were calculated ("slope", after transformation), with and without calibration of nebulizers by weight and adjustment for nonresponse bias. Standardization for baseline lung function and variation in smoking prevalence was applied to slope. Results were robust to whichever summary measure was used, and to the various adjustments. Responsiveness was low in Iceland and Switzerland, and in most centres in Sweden, Italy and Spain, and high in New Zealand, Australia, the USA, Britain, France, Denmark and Germany. Bronchial responsiveness varies considerably in Europe, and high levels are not confined to the English-speaking world.

Determinants of nocturnal enuresis in England and Scotland in the '90s

The aim of this study was to assess whether changes have occurred in the determinants of nocturnal enuresis in Scotland and England in comparison with previous studies. The study was based on 22 study areas from a representative English sample, 14 areas from a representative Scottish sample, and 20 areas from an English inner-city sample. A total of 14,674 subjects was included in the analysis from 16,835 eligible children in the age range 5 to 11 years. For the main analysis, an enuretic child was one who wet the bed at least once a week. As expected, the frequency of enuresis was higher in boys and decreased markedly with age in both sexes. Bedwetting was more frequent in: Afro-Caribbean children compared with white children in the representative samples (OR 1.72 95% CI 1.22 to 2.42); those whose mothers smoked at least 10 cigarettes at home compared with non-smokers (OR 1.58 95% CI 1.26 to 1.98); children who had disturbed sleep compared with those who slept well (OR 1.96 95% CI 1.53 to 2.51); those with mothers aged less than 20 years at the child's birth compared with mothers in the age range 25 to 34 (OR 1.63 95% CI 1.20 to 2.22); and in the second- or third-born in the family in comparison with the first-born (OR 1.42 95% CI 1.17 to 1.72). Father's social class was associated with enuresis only in girls. Only 50% of the parents consulted a doctor for enuresis in their child. The percentage was even lower in Afro-Caribbean families (33%). Enuresis continues to be a highly prevalent problem and has not decreased over the last 45 years. We confirm that environmental factors are still important in the aetiology of enuresis. It is surprising that despite the availability of effective treatment only half of parents consult a doctor about the problem.

Physician-diagnosed asthma and drug utilization in the European Community Respiratory Health Survey

The aim of this analysis was to estimate the geographical variation in the prevalence of physician-diagnosed asthma and treatment practice for asthma in young adults. The results are based on an ecological analysis of 34 centres in 14 countries, in which a total of 17,029 randomly selected subjects (52% females, age 20-48 yrs) underwent a structured interview and spirometry as part of the European Community Respiratory Health Survey. The sample was enriched with 2,903 symptomatic subjects when investigating treatment in subjects with physician-diagnosed asthma. The prevalence of physician-diagnosed asthma was highest in New Zealand and Australia (11-13%) and lowest in Erfurt, Germany (1.2%) and Spain (1.5-3.0%). The reported use of antiasthma medication in the last 12 months was also highest in New Zealand and Australia (12-16%) and correlated closely with the prevalence of diagnosed asthma (r=0.89, p<0.001). Herbal remedies against breathing problems had been used by 13% of subjects in Hamburg but the reported use of alternative remedies for breathing problems was low in most other centres. The use of inhaled anti-inflammatory drugs in subjects with physician-diagnosed asthma ranged from 49% in the UK to 17% in Italy and correlated with the prevalence of doctors' consultations within the last 12 months (r=0.66, p<0.05). The prevalence of anti-inflammatory treatment was positively related to the prevalence of nocturnal asthma symptoms (p<0.05). We conclude that there is a wide geographical variation in the prevalence of physician-diagnosed asthma and use of antiasthma medication. The geographical variation in the use of anti-inflammatory drugs among individuals with diagnosed asthma may be related to variations in asthma severity, as well as differences in treatment practices between countries.

Spleen sizing by ultrasound in polycythaemia and thrombocythaemia: comparison with SPECT

Detection of non-palpable early splenic enlargement may aid diagnosis of primary polycythaemia (PP) and primary thrombocythaemia (PT). In this study linear spleen sizing by ultrasound has been compared with spleen volume estimation by single photon emission computerized tomography (SPECT) in 26 patients. Spleen length by ultrasound correlated well with SPECT volume estimation. Ultrasound spleen length was also measured in 60 normal control subjects where the upper limit of the 95% reference range was 11.6 cm. Changes in spleen length with both age and body weight were substantial and overshadowed the imperfect reproducibility of this method. Therefore, interpretation of an individual's measured spleen length should be in relation to that predicted for adults of the same age and weight, particularly at the extremes of the younger, heavier patients and also the older, lighter patients. Ultrasound spleen lengths of different patient groups (21 PP, 26 PT, 17 idiopathic erythrocytosis, 12 secondary polycythaemia, nine apparent polycythaemia) were compared both using the measured overall reference range and the differences from the values predicted for their age and weight. The comparison showed that almost all patients with PP whose spleens were not palpable had spleen lengths greater than the upper limit for the normal control group, but separation from the other patient groups was incomplete. Detection of non-palpable splenomegaly by ultrasound length should remain a 'minor' criterion amongst the 'proposed modified diagnostic criteria' of PP.

The use of nutritional supplements by 4-12 year olds in England and Scotland

OBJECTIVE

To determine the levels of and factors associated with the use of nutritional supplements by children participating in the National Study of Health and Growth (NSHG).

DESIGN

Cross-sectional study.

SETTING

Fifty-six study areas in England and Scotland.

SUBJECTS

Fifteen thousand, two hundred and seventy five children aged between 4 and 12 y.

INTERVENTIONS

Parental completion of a self-administered questionnaire on the child's health, social background and supplement use. Height, weight and skinfold measurements.

RESULTS

An 88% response rate to the supplement question, 15.9% of responders reported using a supplement. Multivitamins were the most commonly consumed supplement (84%) with 52% taking a supplement daily. Younger children, those whose mothers reached further education, whose fathers were in non-manual occupations or who lived in the Midlands or South were significantly more likely to use a supplement, as were children from smaller families or whose parents were non-smokers. There was no significant association between supplement use and sex, height, birthweight, length of gestation, father's education, number of parents in the home or vegetarianism. Significant differences were found in the use of supplements between the ethnic origin groups. Children of Afro-Caribbean, Asian or other origin were more likely to take a supplement compared to white English and Scottish groups. There were differences in the type of supplements used with Afro-Caribbean and other origin children using more cod liver oil.

CONCLUSION

We support the findings of other studies which show that children with the least need for supplements as defined by socio-economic variables are more likely to receive them and suggest that cultural background is also an important factor in influencing supplement use.

SPONSORSHIP

This study was supported by grants from the Department of Health in England and the Scottish Home and Health Department.

Family size, atopic disorders in parents, asthma in children, and ethnicity

BACKGROUND

Several studies have reported an association between family size and atopic conditions, but few have found an association between asthma and family size.

OBJECTIVE

This study was designed to assess the effect of familial aggregation and sibling number on asthma in children.

METHODS

Children from 5 to 11 years of age in England and Scotland participated in a study in 1990 or 1991 in which responses to questions on asthma and wheezing in children and atopic conditions in parents were ascertained. Data on 11,924 complete family sets of child, mother, and father in three samples (the "representative" samples of England and Scotland and the English "inner city" sample) were analyzed.

RESULTS

The following factors were highly associated with child's asthma or wheezing: mother's or father's asthma or wheezing (with the same odds ratio [OR], 2.4; 95% confidence interval [CI], 2.0 to 2.9), other atopic condition in mothers and fathers (OR, 1.5; 95% CI, 1.3 to 1.8 and OR, 1.4; 95% CI, 1.2 to 1.7, respectively), and three or more siblings compared with no siblings (OR, 0.5; 95% CI, 0.4 to 0.6).

CONCLUSION

The negative relation between family size and wheezing or asthma indicates a protective effect of number of children sharing an environment at a young age. The level of association of asthma or wheezing in the parents and the child and the association between the child's asthma or wheezing and other atopic conditions in parents suggest that a general susceptibility and a lung-specific susceptibility are important in the etiology of asthma.

The distribution of total and specific serum IgE in the European Community Respiratory Health Survey

BACKGROUND

Variations in the prevalence of atopy could provide important clues to the etiology of atopy and asthma. Although estimates of prevalence are available from different studies, a lack of standardization makes comparisons difficult.

OBJECTIVE

This study was conducted to estimate the variation of geometric mean levels of serum IgE and the prevalence of specific IgE to common allergens between populations as part of the European Community Respiratory Health Survey (ECRHS), a multicenter survey of asthma and risk factors for asthma.

METHODS

Random samples of subjects living in 37 centers in 16 countries who had answered a questionnaire about their respiratory symptoms were invited for further assessment including total serum IgE and the presence of specific IgE against house dust mite (Dermatophagoides pteronyssinus), timothy grass, cat, Cladosporium herbarum, and a local allergen. Sera were tested from 13,883 persons.

RESULTS

The estimated prevalence of atopy, defined as the presence of at least one positive specific IgE, ranged from 16% in Albacete (Spain) to 45% in Christchurch (New Zealand). The geometric mean total serum IgE varied from 13 kU/L in Reykjavik (Iceland) to 62 kU/L in Bordeaux (France). There was no relation between the geometric mean total serum IgE in a center and the prevalence of atopy.

CONCLUSIONS

There are substantial variations in the prevalence of atopy and the level of serum IgE. These variations are independent of each other and likely to be largely environmental in origin.

Trends in growth in England and Scotland, 1972 to 1994

AIM

To monitor the growth of 5 to 11 year old English and Scottish children from 1972 to 1994. No similar data are available from any other study.

DESIGN

Mixed longitudinal.

SUBJECTS

In England 7000 children were sampled in the first year, falling to 5000. In Scotland the original sample was 2000 but this was enlarged later to 3500.

MAIN OUTCOME MEASUREMENTS

Height, weight, weight for height index, and triceps skinfold thickness.

RESULTS

Height of English children in most age groups increased by more than 1 cm and by more than 2 cm in Scotland during the period 1972 to 1994. Triceps skinfold measurement increased by almost 8% in 7 year old English boys and by 7% in 7 year old girls. In Scotland triceps skinfold measurement increased by nearly 10% in 7 year old boys and by 11% in 7 year old girls. Weight for height index followed a similar pattern.

CONCLUSION

Children in England and Scotland are becoming taller for a given age. The increases in fatness indicate an urgent need for realistic interventions for reductions in obesity in the whole population. As weight for height index is less sensitive than skinfold thickness we recommend triceps and subscapular skinfold thickness measurements for monitoring obesity in children.

The association of family size with atopy and atopic disease

BACKGROUND

Studies in children have shown that family size is negatively associated with atopy and atopic disease.

OBJECTIVE

To describe the association of family size with atopy and atopic disease in young adults.

METHODS

A randomly selected sample of 1159 men and women aged 20-44 years provided information on respiratory symptoms, hay fever and eczema. Blood samples were taken for assessment of total IgE and specific IgE to house dust mite, grass, cat, Cladosporium and birch. The association of family size and birth order with respiratory symptoms, atopy and total IgE was assessed by multiple logistic and linear regression.

RESULTS

There was a negative association between family size and the reporting of 'wheeze with breathlessness' (adjusted odds ratio for an increase of one sibling 0.85; 95% confidence interval 0.75-0.98), 'wheeze without a cold' (adjusted odds ratio for an increase of one sibling 0.85; 95% confidence interval 0.75-0.98) and 'asthma attacks' in the last 12 months (adjusted odds ratio for an increase of one sibling 0.77; 95% confidence interval 0.61-0.97), current 'hayfever and nasal allergies' (adjusted odds ratio for an increase of one sibling 0.84; 95% confidence interval 0.75-0.94) and sensitization to grass (adjusted odds ratio for an increase of one sibling 0.87; 95% confidence interval 0.76-0.99). Birth order was negatively associated with 'hayfever and nasal allergies' only. A decreased risk of sensitization to grass in those from large families did not fully explain the negative association between family size and hayfever. No statistically significant (P > 0.05) association of family size or birth order with the reporting of other respiratory symptoms, eczema, sensitization to the other allergens or total IgE was observed.

CONCLUSION

There is a negative association between family size and some symptoms suggestive of asthma, 'hayfever and nasal allergies' and sensitization to grass in young adults. There is no consistent, significant association between family size and eczema, total IgE or sensitization to other allergens.

The accuracy of a new system for estimating organ volume using ultrasound

A new system is described for estimating volume from a series of multiplanar 2D ultrasound images. Ultrasound images are captured using a personal computer video digitizing card and an electromagnetic localization system is used to record the pose of the ultrasound images. The accuracy of the system was assessed by scanning four groups of ten cadaveric kidneys on four different ultrasound machines. Scan image planes were oriented either radially, in parallel or slanted at 30 degrees to the vertical. The cross-sectional images of the kidneys were traced using a mouse and the outline points transformed to 3D space using the Fastrak position and orientation data. Points on adjacent region of interest outlines were connected to form a triangle mesh and the volume of the kidneys estimated using the ellipsoid, planimetry, tetrahedral and ray tracing methods. There was little difference between the results for the different scan techniques or volume estimation alogorithms, although, perhaps as expected, the ellipsoid results were the least precise. For radial scanning and ray tracing, the mean and standard deviation of the percentage errors for the four different machines were as follows: Hitachi EUB-240, -3.0 +/- 2.7%; Tosbee RM3, -0.1 +/- 2.3%; Hitachi EUB-415, 0.2 +/- 2.3%; Acuson, 2.7 +/- 2.3%.

Variation in nebulizer aerosol output and weight output from the Mefar dosimeter: implications for multicentre studies

The active aerosol component of nebulizers is less than 100% of output by weight, and may vary between nebulizers in different batches from the same manufacturer. A measure of bronchial responsiveness to methacholine, which can overcome this problem, is required. One hundred and sixty nebulizers from 21 centres in the European Community Respiratory Health Survey (ECRHS) were calibrated for aerosol and weight output. Methacholine challenge data were obtained for 1,021 subjects in three English centres of the ECRHS. The dose producing a 20% fall in forced expiratory volume in one second (PD20), and log-slope, the regression slope of percentage decline in FEV1 with log (dose), were calculated, with and without calibration of nebulizers by weight. Within-centre variation in nebulizer percentage aerosol output had a coefficient of variation of less than 10%. Unlike PD20, log-slope is unaffected by constant percentage overestimation of nebulizer output. Variation in output by weight of nebulizers of 10% had little affect on log-slope. It is, however, affected by the scheduled range of doses. Log-slope shows advantages in analysis, and is less affected by variation in nebulizer output. It can be used for multicentre comparisons, with restriction to a common dose protocol.

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.

Factors related to total cholesterol and blood pressure in British 9 year olds

STUDY OBJECTIVE

To assess which factors are associated with total cholesterol concentration and blood pressure in 9 year olds, and to examine the extent to which a report of a heart attack in a close relative identifies children with a high total cholesterol value or high systolic blood pressure.

DESIGN

This was a cross sectional study.

SETTING

The analysis was based on 22 study areas from a representative English sample, 14 areas from a representative Scottish sample, and 20 areas from an inner city sample.

PARTICIPANTS

There were 1987 children aged 8 or 9 whose blood pressure was measured and 1662 children whose total cholesterol was assessed.

MEASUREMENTS AND MAIN RESULTS

Blood pressure was measured using the Dinamap 1846 automated sphygmomanometer and cholesterol using the Lipotrend C. Multiple regression analysis was used to examine the independent associations with each of the outcome variables. Either weight for height or sum of skinfolds measured in four sites was highly associated with the outcome measures in the study (p < 0.001). Fatter or overweight children had higher blood pressure and higher cholesterol concentrations. Child's height was also associated with the outcome measures in most of the analyses, but was positively related to blood pressure and negatively associated with cholesterol value. There was an association between diastolic blood pressure and area of residence as represented by the regional health authority (RHA), but the association was not the same as the association reported between coronary heart disease, standardised mortality ratio, and RHA. Children with low birth weight and those with shorter gestation had higher systolic blood pressure (p < 0.05 and p < 0.01 respectively), but not diastolic blood pressure. A report of a premature heart attack in a parent or a grandparent was not associated with higher cholesterol or blood pressure.

CONCLUSIONS

Reducing obesity in children, together with the avoidance of smoking, may be an appropriate action to prevent coronary heart disease in adulthood. A report of heart disease in a close relative is an ineffective means of identifying children at greater risk of high cholesterol or blood pressure without other measurements from relatives.

Influence of ethnic group on asthma treatment in children in 1990-1: national cross sectional study

OBJECTIVE

To examine the extent to which the prescription of drugs for asthma adhered to recommended guidelines in 1990-1 and to assess the influence of ethnic group on prescription.

DESIGN

Cross sectional.

SETTING

Primary schools in England and Scotland in 1990-1.

SUBJECTS

Children aged mainly 5-11 years. The representative samples included 10628 children. The inner city sample included 7049 children, 4866 (69%) from ethnic minority groups. For the prevalence estimation 14490 children were included in the analysis (82% of the eligible children). For the treatment analysis a subgroup of 5494 children with respiratory symptoms was selected.

MAIN OUTCOME MEASURES

Prevalence of respiratory symptoms and drugs commonly prescribed for asthma, method of administration, inappropriate treatment, and odds ratios to assess the effect of ethnic group on rate of prescription and method of administration.

RESULTS

Children with respiratory symptoms in the inner city sample were less likely to be diagnosed as having asthma. Of children with reported asthma attacks, those in inner city areas had a higher risk of not having been prescribed any drug for asthma (odds ratio 1.87 (95% confidence interval 1.26 to 2.77). Overall, 773 (75%) of these children had received a beta 2 agonist, 259 (25%) had received steroids, 148 (14%) had received sodium cromoglycate, and 194 (19%) had received no drug treatment in the previous year. When prescribed, beta 2 agonists were inhaled in 534 (69%) of cases, and this percentage was even lower in ethnic minority groups. Children of Afro-Caribbean and Indian subcontinent origin who had asthma were less likely to receive beta 2 agonists, and those from the Indian subcontinent were less likely to receive anti-inflammatory drugs. Antibiotics were less prescribed and antitussives more prescribed in children from ethnic minority groups than in white children.

CONCLUSION

In 1990-1 the risk of underdiagnosis and undertreatment of asthma was higher in children from ethnic minority groups. The implementation of indicators and targets to monitor inequalities in the treatment of asthma in ethnic groups could improve equity and effectiveness in the NHS.

Measuring atopy in a multi-centre epidemiological study

Skin prick tests are used as a measure of atopy in epidemiological studies, but results may be influenced by the fieldworker performing the test. In a multi-centre epidemiological study the method of reporting the results should consider the need for comparability of findings from different centres. Data on over 1000 subjects from three English centres of the European Community Respiratory Health Survey were analysed to determine whether allergen wheal should be adjusted for histamine wheal, and what cutoff diameter gave the most comparable results. No consistent relation between allergen wheal diameter and histamine wheal diameter was found for any fieldworker or allergen. A cutoff of > 0 mm for a positive result gave a more consistent relation with the corresponding specific IgE value between fieldworkers than either a cutoff of > or = 3 mm or the use of the mean wheal diameter. While this result is not immediately generalisable to studies using different skin prick test reagents, the method of analysis to determine the appropriate criterion of reporting can be used in other epidemiological studies.

Family Credit and uptake of school meals in primary school

BACKGROUND

In April 1988, Family Credit families lost their right to free school meals. They were compensated by an increase in Family Credit of 65p per child per schoolday, subsequently uprated by the retail price index. Families on Income Support continued to be entitled to free school meals. The impact of this legislation on the uptake of school meals has not been documented.

METHODS

The uptake of school meals by Family Credit and income Support families over a decade was examined in two samples, each consisting of about 7000 English primary school children, one of "inner city' children and the other more representative of the whole population.

RESULTS

The change in legislation resulted in an immediate drop in uptake by Family Credit children of around 30 per cent in both samples. By ethnic group, 42 per cent of the Asian Family Credit children changed from school meals compared with 10 per cent of the Afro-Caribbean children. Income Support children continued to have high uptake of about 90 per cent. By the early 1990s, half of the Family Credit children were not taking school meals, and the price of school meals was more than the allowance in 81 per cent of the areas in the representative sample, and in 45 per cent of the inner city areas.

CONCLUSION

Uptake of school meals is very sensitive to changes in welfare policy. Monitoring the impact of these changes on children's health and welfare in families with low resources continues to be an important activity.

Association of respiratory symptoms and lung function in young adults with use of domestic gas appliances

BACKGROUND

There is evidence from some studies that people living in homes with gas stoves and other unvented gas appliances experience more respiratory symptoms than those who use other fuels for cooking and heating, but other studies have found no such association. We have investigated whether the use of gas appliances is associated with an increased risk of respiratory symptoms and whether sensitisation to common environmental allergens modifies any such association.

METHODS

A stratified random sample of 15,000 adults aged 20-44 years, living in three towns in East Anglia, UK, were sent a questionnaire on asthma and hayfever. From those who responded, a random sample of 1864 were invited to complete an extended questionnaire that included questions on use of gas appliances, to give blood samples for measurements of total IgE and specific IgE to common allergens, and to undergo tests of respiratory function, 659 women and 500 men agreed to an interview. The association of the use of gas appliances with respiratory symptoms, total IgE, specific IgE, and respiratory function was assessed by logistic and multiple regression models.

FINDINGS

Women who reported they mainly used gas for cooking had an increased risk of several asthma-like symptoms during the past 12 months including wheeze (odds ratio 2.07 [95% CI 1.41-3.05]), waking with shortness of breath (2.32 [1.25-4.34]), and asthma attacks (2.60 [1.20 -5.6]). Gas cooking increased the risk of symptoms more in women who were atopic than in non-atopic women but the difference did not reach significance (p . 0.05). Women who used a gas stove or had an open gas fire had reduced lung function (forced expiratory volume in 1 s [FEV1]) and increased airways obstruction (FEV1 as a percentage of forced vital capacity) compared with women who did not. These associations were not observed in men.

INTERPRETATION

In East Anglia, the use of gas cooking is significantly associated with subjective and objective markers of respiratory morbidity in women but not in men. Women may be more susceptible than men to the products of gas combustion or they may have greater exposure to high concentrations of these products because they cook more frequently than men.

The association of age, gender and smoking with total IgE and specific IgE

BACKGROUND

Smoking has been identified as a risk factor for atopy but there are difficulties in interpreting many of the previous studies because the subjects who have been studied have not been representative of the entire population and because there is confounding between gender and smoking.

OBJECTIVE

To investigate the association of age, gender and smoking with total IgE and specific IgE to house dust mite, grass and cat.

METHODS

A stratified random sample of 20-44 year olds living in three centres in East Anglia and registered with a local general practitioner had blood taken for total immunoglobulin E (IgE) and specific IgE. A smoking history was obtained from a structured interviewer-led questionnaire.

RESULTS

Among non-smokers geometric mean total IgE was higher in men than women but unrelated to age. Smoking explained less than 1% of the variation in total IgE. Smoking was associated with an increased risk of sensitization to house dust mite (odds ratio 1.59; 95% confidence interval 1.02-2.48) but a decreased risk of sensitization to grass (odds ratio 0.45; 95% confidence interval 0.28-0.71) and cat (odds ratio 0.47; 0.24-0.94).

CONCLUSION

Men aged 20-44 years have higher total IgE levels than women of the same age. In young adults smoking explains little of the variation in total IgE and its association with sensitization to common allergens varies between allergens.

Factors associated with weight for height and skinfold thickness in British children

STUDY OBJECTIVE

To examine the associations of social and biological factors with measures of obesity in children.

DESIGN

The study had a cross sectional design.

SETTING

The analyses were based on data from two national study of health and growth cross sectional surveys. The "representative sample" comprised 1990 data from 22 English areas and 1990-91 data from 14 Scottish areas; the "inner city sample" comprised 1991 data from 20 English areas.

PARTICIPANTS

The subjects were primary school children aged mainly 5-11 years living in England and Scotland. The "representative" sample included 10,628 children--6463 living in England and 4165 living in Scotland. The "inner city" sample included 7049 children--2183 white, 1124 Afro-Caribbean, 2696 Indian subcontinent, and 1046 from other groups. Due to missing values on continuous variables, 8374 children were included in the analyses.

MEASUREMENTS AND MAIN RESULTS

The relation between social environment and childhood overweight was studied using several indicators of obesity. Triceps, subscapular, the sum of triceps and subscapular skinfolds, and weight for height were used as dependent variables. The analyses were carried out in two stages. Firstly, multiple linear regression analyses were used to assess the factors associated with dependent variables treated as continuous. Secondly, multiple linear logistic regression analyses were used to examine the association between independent factors and overweight and fatness defined as binary variables. Birth weight, mother's body mass index (BMI), and father's BMI were consistently associated (p < 0.001) in all models and were the variables that contributed most to the explained variation in the dependent variables. In the multiple regression analyses there was a consistent interaction between the effects of ethnic origin and family size on each outcome variable. In the logistic regression analyses the interaction was not significant, and highly significant associations between both overweight and fatness with the number of children were shown. Ethnic group was not significantly associated with overweight but it was with fatness. The strengths of the remaining significant associations were slight and inconsistent in relation to the dependent variables or the type of analysis.

CONCLUSION

Very few variables were associated with measures of overweight and fatness. The only useful factor that was highly associated with all measures of fatness was the parents' BMI. Strategies to prevent childhood obesity should be aimed at the total population and special emphasis should be placed on families in which one or both parents are overweight.

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.

Genetic and environmental influences on growth

OBJECTIVES

To provide an overview of the factors associated with growth in primary school children in England and Scotland and to provide information about the secular trend of growth in the last 20 years.

SETTING

Representative English and Scottish samples and an English inner city sample.

METHODS

The study had a mixed longitudinal design from 1972 to 1994. Between 8000 and 10,000 children participated in each survey. Height was measured in at least 95% of the children in most surveys, and 75% to 85% of parents provided information about family background. Main results are based on published information. Multiple regression was used for most of the analyses.

RESULTS

Parents' height, child's birth weight, mother's age at child's delivery, ethnic background and, in white children, family size are the only factors markedly associated with height. Variables that have traditionally been used to assess the possible effect of social conditions were generally not associated with height. The height increase was more marked in Scotland than England over the period 1972 to 1990, and the differences in height of children in the two countries is now minimal.

CONCLUSIONS

Most factors cannot be neatly classified as purely genetic or environmental, but seem to indicate that genes are relatively more important. Social factors usually assessed in growth studies do not have an important effect on growth. The marked increase of height over time indicates that the environment and social conditions have allowed children to grow taller. Sibship size is the only factor that was shown to be related to the secular trend in growth.

Cross sectional stature and weight reference curves for the UK, 1990

The current reference curves of stature and weight for the UK were first published in 1966 and have been used ever since despite increasing concern that they may not adequately describe the growth of present day British children. Using current data from seven sources new reference curves have been estimated from birth to 20 years for children in 1990. The great majority of the data are nationally representative. The analysis used Cole's LMS method and has produced efficient estimates of the conventional centiles and gives a good fit to the data. These curves differ from the currently used curves at key ages for both stature and weight. In view of the concerns expressed about the current curves and the differences between them and the new curves, it is proposed that the curves presented here should be adopted as the new UK reference curves.