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Biomedical subjects

R Beasley

Publications and source records attributed to R Beasley.

At least 55 records · Page 3Linked to original sources
PubMed2000

Is allergen exposure the major primary cause of asthma?

In recent decades a number of authors have argued that allergen exposure is the major primary cause of asthma, and that the global increases in asthma prevalence are due to increases in exposure to aeroallergens. We have assessed the epidemiological evidence in support of this hypothesis. No longitudinal studies were identified in which allergen exposure during infancy in a random population sample has been related to asthma risk after the age of six years. Two studies have been conducted in selected populations chosen on the basis of a family history of asthma or allergy; one study found a non-statistically significant association whereas the other study found no association. Many of the identified prevalence studies in children showed negative associations between allergen exposure and current asthma, and the weighted averages of the population attributable risks in children were 4% for Der p 1, 11% for Fel d 1, -4% for Bla g 2, and 6% for Can f 1. There was little change in these estimates in studies in which children whose parents had adopted allergen avoidance measures were excluded. Furthermore, evidence from population studies is equivocal and provides little consistent evidence that allergen exposure is associated with the prevalence of asthma at the population level. Population-based cohort studies are clearly required, but currently available evidence does not indicate that allergen exposure is a major risk factor for the primary causation of asthma in children.

Allergens↗
PubMed2000

International patterns of tuberculosis and the prevalence of symptoms of asthma, rhinitis, and eczema.

BACKGROUND: An ecological analysis was conducted of the relationship between tuberculosis notification rates and the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema in 85 centres from 23 countries in which standardised data are available. These essentially comprised countries in Europe as well as the USA, Canada, Australia, and New Zealand. METHODS: Tuberculosis notification rates were obtained from the World Health Organization. Data on the prevalence of symptoms of asthma, rhinitis, and eczema in 235 477 children aged 13-14 years were based on the responses to the written and video questionnaires from the International Study of Asthma and Allergies in Childhood (ISAAC). The analysis was adjusted for gross national product (GNP) as an estimate of the level of affluence. RESULTS: Tuberculosis notification rates were significantly inversely associated with the lifetime prevalence of wheeze and asthma and the 12 month period prevalence of wheeze at rest as assessed by the video questionnaire. An increase in the tuberculosis notification rates of 25 per 100 000 was associated with an absolute decrease in the prevalence of wheeze ever of 4.7%. Symptoms of allergic rhinoconjunctivitis in the past 12 months were inversely associated with tuberculosis notification rates, but there were no other significant associations with other ISAAC questions on allergic rhinoconjunctivitis or atopic eczema. CONCLUSIONS: These findings are consistent with recent experimental evidence which suggests that exposure to Mycobacterium tuberculosis may reduce the risk of developing asthma.

Adolescent↗
PubMed1999

Beta-agonists: what is the evidence that their use increases the risk of asthma morbidity and mortality?

In this article, studies that have examined the effects on morbidity and mortality of beta-agonist drugs are reviewed. With regard to morbidity, there is considerable evidence that the regular use of beta-agonist drugs as a class could potentially lead to worsening asthma control because of the effects on bronchial hyperresponsiveness, the development of tolerance and reduced protection against provoking stimuli, an increased allergen load, and masking of the symptoms of deteriorating asthma. Despite these effects, the short-acting beta-agonist drugs albuterol and terbutaline and the long-acting beta-agonist drugs salmeterol and formoterol have, in general, not been associated with a significant worsening of asthma control or an increased frequency of severe attacks. In contrast, there is evidence that the regular use of isoproterenol and fenoterol may lead to worsening asthma control. With regard to deaths, available evidence indicates that the high-dose preparations of isoproterenol and fenoterol are associated with increased mortality and were the major causes of the epidemics of asthma mortality observed in some countries. The increased risk of death associated with isoproterenol and fenoterol is probably the result of both long-term effects with their regular use leading to worsening asthma control and acute effects resulting from their overuse in the situation of a life-threatening attack of asthma. In contrast, the use of the short-acting beta-agonists albuterol and terbutaline is not associated with an increased risk of mortality. Although this lack of risk may also apply to formoterol and salmeterol, in the absence of sufficient studies specifically addressing the risk of death, this remains uncertain.

Adrenergic beta-Agonists↗
PubMed1999

The magnitude of the effect of smaller family sizes on the increase in the prevalence of asthma and hay fever in the United Kingdom and New Zealand.

BACKGROUND: Declining family size is one factor that has been proposed to contribute to increasing asthma and hay fever prevalence, but its relative importance has not been quantified. OBJECTIVE: Our purpose was to determine the change in asthma and hay fever prevalence that would be expected from the reduction in family size that has occurred in England/Wales and New Zealand over recent decades. METHODS: The relative change in family size between 1961 and 1991 in England/Wales and New Zealand was determined from census data for these years. Summary weighted odds ratios were calculated for the associations among birth order, family size, and asthma and hay fever prevalence. The expected increase in the prevalence of asthma and hay fever between 1961 and 1991 resulting from changes in family size was then calculated. RESULTS: The expected relative increase in the prevalence of asthma between 1961 and 1991 as a result of the smaller family size was 1% and 5% for England/Wales and New Zealand, respectively; smaller family size would be expected to increase the prevalence of hay fever prevalence in England/Wales by 4%. CONCLUSIONS: Changes in family size over the last 30 years do not appear to explain much of the reported increase in asthma or hay fever prevalence. The contribution that other risk factors have made to these increases could be assessed with use of a similar approach.

Asthma↗
PubMed1999

Worldwide variations in the prevalence of symptoms of atopic eczema in the International Study of Asthma and Allergies in Childhood.

BACKGROUND: Little is known about the prevalence of atopic eczema outside Northern Europe. OBJECTIVES: We sought to describe the magnitude and variation in the prevalence of atopic eczema symptoms throughout the world. METHODS: A cross-sectional questionnaire survey was conducted on random samples of schoolchildren aged 6 to 7 years and 13 to 14 years from centers in 56 countries throughout the world. Those children with a positive response to being questioned about the presence of an itchy relapsing skin rash in the last 12 months that had affected their skin creases were considered to have atopic eczema. Children whose atopic eczema symptoms resulted in sleep disturbance for 1 or more nights per week were considered to have severe atopic eczema. RESULTS: Complete data was available for 256,410 children aged 6 to 7 years in 90 centers and 458,623 children aged 13 to 14 years in 153 centers. The prevalence range for symptoms of atopic eczema was from less than 2% in Iran to over 16% in Japan and Sweden in the 6 to 7 year age range and less than 1% in Albania to over 17% in Nigeria for the 13 to 14 year age range. Higher prevalences of atopic eczema symptoms were reported in Australasia and Northern Europe, and lower prevalences were reported in Eastern and Central Europe and Asia. Similar patterns were seen for symptoms of severe atopic eczema. CONCLUSIONS: Atopic eczema is a common health problem for children and adolescents throughout the world. Symptoms of atopic eczema exhibit wide variations in prevalence both within and between countries inhabited by similar ethnic groups, suggesting that environmental factors may be critical in determining disease expression. Studies that include objective skin examinations are required to confirm these findings.

Adolescent↗
PubMed1999

The relationship between anthropometric measurements at birth: asthma and atopy in childhood.

BACKGROUND: Recent studies have reported that a large head circumference at birth is associated with an increased risk of raised serum IgE in adult life, and asthma during childhood. OBJECTIVE: To examine the relationship between head circumference and other anthropometric measurements at birth and asthma and indices of atopy in childhood. METHODS: The presence of asthma and measures of atopic status (total serum IgE level and skin prick tests to common allergens) were assessed prospectively in offspring of families participating in a community-based genetic study in Southampton, UK. Measures of perinatal variables including birth weight, head circumference at birth, and gestational age were obtained from hospital records of 239 offspring aged 6-23 years. RESULTS: Children with a head circumference of 37 cm or more at birth had a relative risk of an elevated serum total IgE (> 150 IU) of 3.2 (95% CI 1.0-10.4). There were no consistent relationships between head circumference at birth and either skin prick positivity or the development of clinical asthma. There was no significant association between other perinatal markers and measures of atopic status or clinical asthma. CONCLUSION: The study has identified that a large head circumference at birth is associated with an increased risk of an elevated total serum IgE in childhood. The reasons for this association, and the lack of an association with asthma are unclear and will require further research.

Adolescent↗
PubMed1999

Antibiotic use in early childhood and the development of asthma.

BACKGROUND AND OBJECTIVE: Recent investigations have focused on the role of infections in infancy in promoting or protecting against the subsequent development of asthma. A related hypothesis concerns the possible role of medical responses to infections, including the widespread use of antibiotics. We chose children at Rudolf Steiner schools to test this latter hypothesis because a significant proportion of parents rejects the use of conventional treatments, including antibiotics. METHODS: Seventy-five per cent (n = 456) of parents of children aged 5-10 years attending Rudolf Steiner schools throughout New Zealand completed questionnaires which included questions on the use of antibiotics and a history of asthma and wheeze in their children. RESULTS: After controlling for potential confounders, antibiotic use was significantly associated with having a history of asthma (OR = 2.74, 95% CI: 1.10-6.85) or wheeze (OR = 1. 86, 95% CI: 1.06-3.26) but not with current wheeze (OR = 1.08, 95% CI: 0.54-2-16). The adjusted odds ratio for asthma was 4.05 (95% CI: 1.55-10.59) if antibiotics were used in the first year of life and 1. 64 (95% CI: 0.60-4.46) if antibiotics had been used only after the first year of life when compared with children who had never used antibiotics. The number of courses of antibiotics during the first year of life was also associated with increased odds ratios for asthma: 2.27 (95% CI: 1.14-4.51) for one to two courses and 4.02 (95% CI: 1.57-10.31) for three or more courses when compared with no antibiotic use in the first year of life. Although not significant, the association of antibiotics and hay fever (OR = 1.99 [95% CI: 0. 93-4.26]) was of a similar strength to the association of antibiotics with a history of wheeze. Antibiotics were not significantly associated with eczema (OR = 1.23 [95% CI: 0.71-2.13]). CONCLUSION: Antibiotic use in infancy may be associated with an increased risk of developing asthma. Further study is required to determine the reasons for this association.

Anti-Bacterial Agents↗
PubMed1999

Relationship between fetal growth and the development of asthma and atopy in childhood.

BACKGROUND: A study was undertaken to investigate the relationship between birth anthropometric measures and the subsequent development of asthma, airway hyperresponsiveness, and atopy in later childhood. METHODS: A longitudinal study was performed on 734 subjects (71%) from a cohort of children born in Dunedin, New Zealand in 1972-73. The birth anthropometric measures were available from hospital records and the main outcome measures of reported asthma, skin prick tests, and methacholine hyperresponsiveness were measured at the age of 13 years, while the serum total IgE was measured at 11 years. RESULTS: After adjustment for other factors, infants with a larger head circumference at birth tended to have higher serum total IgE at 11 years of age (p = 0.02) but IgE was not associated significantly with birth length or birth weight. The adjusted odds ratio for raised serum IgE (>150 IU/ml) in infants with a head circumference of 37 cm or more was 3.4 (95% CI 1.4 to 7.9). In contrast, recent asthma symptoms were positively associated with birth length (p = 0. 04) but not with head circumference. The adjusted odds ratio for asthma in the previous two years in infants with a birth length of 56 cm or more was 6.4 (95% CI 2.0 to 19.8). Infants with a birth weight of less than 3.0 kg had an odds ratio for reported asthma of 0.2 (95% CI 0.0-0.6). There were no significant associations of any of the birth parameters with skin prick positivity, reported hay fever, or eczema. CONCLUSIONS: These results suggest that increased fetal growth is related to an increased risk of asthma and atopy in childhood. The precision of the findings is limited by the small numbers in the extreme categories of each birth parameter, but the results are consistent with intrauterine programming of the developing respiratory and immune systems.

Adolescent↗
PubMed1999

Analysis of two IL-4 promoter polymorphisms in a cohort of atopic and asthmatic subjects.

The Th2 cytokine interleukin 4 (IL-4) has been identified as having a central role in driving the inflammatory immune responses which are present in atopic airway disease. This study examined the distribution of two putative IL-4 promoter polymorphisms (-285 C-T and -81 A-G) in groups of patients with severe and moderate asthma, non-asthmatic atopy and control subjects. Neither polymorphism was identified in any of the samples tested. The data suggest that either the polymorphisms are present at very low frequencies or are artefacts of the B cell lines from which they were identified.

Adult↗
PubMed1999

Measuring morbidity in adult asthmatics.

SETTING: Whereas prevalence studies usually involve a general population sample, morbidity studies often involve the evaluation of factors that affect asthma severity within an asthmatic population. OBJECTIVE: To review methods of measuring morbidity in adult asthmatics, and to assess the appropriateness of the available methods in a variety of research contexts. FINDINGS: As in prevalence studies, symptoms are the cornerstone of studies of asthma morbidity. These may be supplemented by physiological measures including daily peak flow measurement, but bronchial hyper-responsiveness (BHR) testing is usually impractical, and there is no simple relationship between current asthma severity and current levels of BHR in individuals. Health service and medication usage are often taken as measures of asthma morbidity, but they may be inappropriate in studies in which increased contact with the health services is an intended or unintended effect of participation. Measures of quality of life can be a useful complement to more 'objective' methods. CONCLUSIONS: In studies of morbidity in adult asthmatics, the emphasis should be on using 'appropriate methodology', and methods that may be appropriate in one context may be completely inappropriate in another.

Adult↗
PubMed1998

Comparison of potency of inhaled beclomethasone and budesonide in New Zealand: retrospective study of computerised general practice records.

OBJECTIVE: To determine whether inhaled budesonide and beclomethasone are equipotent in the treatment of asthma in primary care. DESIGN: Retrospective study of computerised clinical records from 28 general practices in New Zealand. SUBJECTS: 5930 patients who received 16 725 prescriptions for inhaled budesonide or beclomethasone from 1 July 1994 to 30 June 1995. SETTING: General practices on the database of the Royal New Zealand College of General Practitioners Research Unit. Linked information from secondary care was available for a subset of the practices. MAIN OUTCOME MEASURE: Mean prescribed daily inhaled corticosteroid dose. RESULTS: The daily prescribed dose was higher for patients receiving inhaled budesonide (mean 979 microg) than beclomethasone (mean 635 microg), a difference of 344 microg (95% confidence interval 313 to 376 microg). This difference was consistent in all age bands and with different types of inhalation device. Evidence of systematic prescribing of higher doses of budesonide to patients with more severe asthma was not found. CONCLUSIONS: In primary care in New Zealand evidence suggests that budesonide is less potent than beclomethasone. Consideration of validated, established, and other possible markers of asthma severity did not support confounding by severity as a reason for the higher prescribed doses of budesonide. Pending further epidemiological evaluation, international asthma guidelines may need to be modified on the equivalence of inhaled corticosteroid doses. Furthermore, the comparative potency of newly developed inhaled steroids in clinical trials will need to be confirmed in appropriately designed epidemiological studies based in general practice.

Administration, Inhalation↗
PubMed1998

Biologic pollution in infant bedding in New Zealand: high allergen exposure during a vulnerable period.

BACKGROUND: High exposure to house dust mite and cat allergens in early life predisposes to allergic sensitization and to the development and persistence of asthma. Prevalence and severity of asthma are high in New Zealand. OBJECTIVE: The objective of this study was to determine the concentrations of Der p 1 and Fel d 1 in infant bedding in Wellington, New Zealand. METHODS: Infants were visited at home at a mean age of 11 weeks and again at 15 months. The concentration (microgram/g fine dust) and content (microgram/m2) of Der p 1 (154 infants) and Fel d 1 (75 infants) were measured in dust samples taken from each infant's bed. RESULTS: At 11 weeks, geometric mean (95% confidence intervals) Der p 1 levels were 18.3 micrograms/g (13.8 to 24.1) and 3.51 micrograms/m2 (2.4 to 5.2). By 15 months, Der p 1 had risen significantly to 44.0 micrograms/g (35.0 to 55. 3) and 49.0 micrograms/m2 (36.0 to 66.8). Bedding that included a sheepskin was used by a third of the infants and contained higher concentrations (microgram/g) and content (microgram/m2) of Der p 1 than beds without sheepskins. Cat ownership was the major determinant of Fel d 1 levels, with 48% of infants living with cats. At the first visit, the mean concentration of Fel d 1 in bedding was 44.6 micrograms/g (23.5 to 84.9) for houses with cats and 3.0 micrograms/g (2.1 to 4.3) for those without cats, remaining essentially unchanged at the second visit. When expressed as micrograms per square meter, there was a significant increase between visits, from 8.1 (3.9 to 16. 6) to 39.6 (19.9 to 78.5) in the cat-inclusive households. CONCLUSIONS: Extremely high levels of house dust mite allergen have been found in these infants' environments, which, together with the high levels of cat allergen in almost half who kept cats, are likely to be a major determinant of asthma prevalence and severity in New Zealand.

Allergens↗