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Biomedical subjects

M I Asher

Publications and source records attributed to M I Asher.

At least 37 records · Page 2Linked to original sources
PubMed1995

International Study of Asthma and Allergies in Childhood (ISAAC): rationale and methods.

The aetiology of asthma and allergic disease remains poorly understood, despite considerable research. The International Study of Asthma and Allergies in Childhood (ISAAC), was founded to maximize the value of epidemiological research into asthma and allergic disease, by establishing a standardized methodology and facilitating international collaboration. Its specific aims are: 1) to describe the prevalence and severity of asthma, rhinitis and eczema in children living in different centres, and to make comparisons within and between countries; 2) to obtain baseline measures for assessment of future trends in the prevalence and severity of these diseases; and 3) to provide a framework for further aetiological research into genetic, lifestyle, environmental, and medical care factors affecting these diseases. The ISAAC design comprises three phases. Phase 1 uses core questionnaires designed to assess the prevalence and severity of asthma and allergic disease in defined populations. Phase 2 will investigate possible aetiological factors, particularly those suggested by the findings of Phase 1. Phase 3 will be a repetition of Phase 1 to assess trends in prevalence.

Adolescent↗
PubMed1994

Prevalence, severity and medical management of asthma in European school children in 1985 and 1991.

This present study, conducted in 1991, examined trends in the prevalence, severity and medical management of asthma in European school children by repeating the protocol of a study performed in 1985, using the same schools and questionnaire. One thousand, nine hundred and one children in 1991 were compared with 1084 children in 1985. The prevalence of respiratory symptoms increased significantly by approximately one-third, although the increase in the diagnostic label 'asthma' did not increase significantly. Asthma severity indices (> 12 asthma attacks in the last 12 months and symptoms in the last month) were not significantly increased, except for night cough in the last month (1985 7.0%, 1991 9.9%, P = 0.008). In 1991, children with wheeze in the last 12 months were more likely to be diagnosed as having asthma and treated with bronchodilators and prophylactic drugs than in 1985. We conclude that the prevalence of asthma symptoms has increased from 1985 to 1991, but the two indices of severity of asthma are mostly unchanged. Diagnosis of asthma in children with symptoms has improved but asthma still appears underrecognized. Drug treatment of asthma has increased.

Adolescent↗
PubMed1991

A tool for measuring the asthma self-management competency of families.

A tool for measuring a family's asthma self-management behaviour has been developed for a study examining the relationships of asthma self-management behaviour, knowledge, and psychosocial factors with various indices of morbidity in children with asthma. The tool involves a structured interview which includes three typical situations of asthma self-management (scenarios). Each of the scenarios is divided into graded challenges. A scoring schedule was developed according to the critical incidents of self-management inherent in each situation. This schedule was then applied to the verbatim transcripts of the subjects' responses. These were presented to 380 asthmatic children aged 5-11 yr and their primary caregivers. Inter-rater reliability, inter-rater agreement and test-retest reliability coefficients indicate that the scores obtained are stable across raters and time. Correlations between scores on different scenarios suggest there is a common factor of self-management competency across all scenarios, but families are better at some aspects of self-management than others. The distribution of scores for each scenario is presented. The place of this tool as a means of assessing self-management behaviour is discussed.

Asthma↗
PubMed1990

Effects of chest physical therapy on lung function in children recovering from acute severe asthma.

The effects of chest physical therapy in acute severe asthma in children have been studied in 38 children aged 6 to 13 years in a randomized placebo controlled trial. The study began between 6 and 24 hours after admission to hospital; 19 children received chest physical therapy (PT) and 19 children received placebo visits. Each child had 4 treatments over 2 days which were preceded by nebulized salbutamol. Lung volumes and flow rates were measured in a body plethysmograph before salbutamol and before and after either PT or placebo on the first and fourth treatments. Throughout the study standard asthma drug therapy was given. In both groups characteristics such as sex, race, age, height, weight, severity, and baseline lung function were similar. Taking into account the baseline, lung function at the end of the study was similar in both groups. Three 12 year old children in the PT group showed improvements in flows above those seen in any children in the placebo group. We conclude that chest PT, when combined with asthma drug therapy, does not improve lung function in most children in this age group with acute severe asthma.

Adolescent↗
PubMed1990

The interrelationship among bronchial hyperresponsiveness, the diagnosis of asthma, and asthma symptoms.

Bronchial hyperresponsiveness (BHR) to inhaled histamine has often been cited as the gold standard in asthma diagnosis, but recently this has been questioned. This report assesses the relationship of BHR to asthma symptoms and asthma diagnosis in a large community-based sample of children. A total of 2,053 children 7 to 10 yr of age were randomly sampled from Auckland primary schools and assessed by a questionnaire and histamine inhalation challenge. In all, 14.3% had had asthma diagnosed, 29.6% reported having had one of the four respiratory symptoms in in the previous 12 months, and 15.9% had BHR (PD20 less than or equal to 7.8 mumol histamine). After a cumulative dose of 3.9 mumol histamine, the percent change in FEV1 from postsaline FEV1 was unimodally distributed, with those in whom asthma had been diagnosed dominating the severe end of the spectrum. However, 53% of those with BHR had no asthma diagnosis, and 41% had no current asthma symptoms. On the other hand, 48% of all subjects with diagnosed asthma and 42% of children with diagnosed asthma and current symptoms did not have BHR. Although severity of BHR tended to increase with wheezing frequency, all grades of severity (including no BHR) were found for any given frequency of wheeze. An existing diagnosis of asthma identified symptomatic children more accurately than did BHR, regardless of the criteria used for BHR or for "symptomatic" and irrespective of ethnic group. In conclusion, BHR is related to, but not identical to, clinical asthma. Bronchial challenge testing is an important tool of respiratory research, but cannot reliably or precisely separate asthmatics from nonasthmatics in the general community.

Asthma↗
PubMed1989

Socioeconomic status in childhood asthma.

This study examines the relationship between socioeconomic status (SES) and asthma prevalence and the use of asthma medication. One thousand and fifty European children aged eight and nine years were studied by parent completed questionnaire and histamine inhalation challenge. After controlling for sex of the child and for smokers in the house there were significantly higher lifetime (P = 0.029) and current (P = 0.046) prevalence rates of wheeze in children in low SES groups. There was no relationship between SES and asthma diagnosis, bronchial hyperresponsiveness (BHR: PD20 less than 7.8 mumol), or any combination of BHR with symptoms or diagnosis. The use of bronchodilators and asthma prophylactic drugs was less frequent in the low SES groups of children with wheeze in the last 12 months both with concurrent BHR or irrespective of BHR than in those in high SES groups.

Asthma↗
PubMed1989

Ethnic differences in prevalence of asthma symptoms and bronchial hyperresponsiveness in New Zealand schoolchildren.

Maoris and Pacific Islanders in New Zealand have a higher asthma mortality and hospital admission rates than Europeans. To determine whether difference in asthma prevalence is the major factor underlying these differences in mortality, 2053 Auckland children aged 7-10 years (European 1084, Maori 509, Pacific Islander 460) were randomly sampled from school classes in the Auckland Urban Area, and studied by questionnaire (completed by parents) and histamine inhalation challenge to assess the provocative dose of histamine causing a 20% fall in FEV1 (PD20). Maoris had the highest prevalence rates of respiratory symptoms, and Europeans had rates similar to Pacific Islanders. For "any current wheeze" for example, the prevalence in Maoris was 22.2% compared with 16.1% and 16.3% in the Europeans and Pacific Islanders. The prevalence of diagnosed asthma was similar in the three groups. When bronchial hyperresponsiveness (defined as a PD20 less than or equal to 7.8 mumol histamine) was considered, Europeans had the highest rates (20%), followed by Maoris (13%), and then Pacific Islanders (8.7%). These differences were not accounted for by differences in socioeconomic status, rates of smoking in the home, age, gender, or height. It is concluded that differences in asthma prevalence do not satisfactorily explain the mortality and admission rate differences, although the higher symptom prevalence in the Maoris could be relevant to the higher mortality rate. Maori and Pacific Island children with symptoms of asthma were less likely to be taking prophylactic medication than European children. It is proposed that differences in management are important factors relevant to the increased mortality and morbidity from asthma in Polynesians.

Asthma↗
PubMed1988

International comparison of the prevalence of asthma symptoms and bronchial hyperresponsiveness.

Potential explanations for the higher rates of asthma mortality and hospital admissions in New Zealand (NZ) include greater prevalence of asthma. To evaluate this further, a large community survey has been undertaken. Rates of respiratory symptoms and bronchial hyperresponsiveness (BHR) for children in Auckland, NZ have been compared to those for children in two locations in New South Wales (NSW), Australia: Wagga Wagga (inland) and Belmont (coastal). The methodology used was the same in both studies: parent-completed questionnaire and BHR measured by response to an abbreviated histamine challenge. In Auckland, 1,084 children participated (84% of those selected) and were compared to 769 inland NSW and 718 coastal NSW children. The prevalence of respiratory symptoms, BHR, severity of BHR, and BHR combined with symptoms was similar among Auckland and inland NSW children but lower among coastal NSW children than those from the other two sites. It is concluded that other unidentified factors must be invoked to explain mortality and admission differences between these regions.

Asthma↗
PubMed1987

Removal of observer variability from the determination of the volume of isoflow.

The initial attractiveness of the volume of isoflow (VisoV) as an index of early small airways dysfunction has faded, perhaps because of VisoV's high variability, a significant part of which is contributed by the observer. We suggest here that the observer variability can be removed by filtering the flow data in the reciprocal volume domain, by using a modified foreign gas mixture in which some of the helium is replaced by neon, and by reading VisoV from a plot of density dependence vs. lung inflation. Support for these suggestions is drawn from both model simulations and experiments. Model simulations suggested that VisoV would be increased by the substitution of neon for some of the helium in the usual helium-oxygen (Helox) mixture. This was confirmed in tests on matched groups of normal and asymptomatic asthmatic children. The inclusion of 20% neon (Heneox20) was found to reduce the coefficient of variation in the mean value of VisoV in both groups of subjects. An interesting result of this test was that VisoV using Heneox20 was significantly higher in the asthmatic group than in the normal group, whereas VisoV using Helox was not. The results for density dependence (DD) between the 2 groups were not significantly different using Heneox20 but were using Helox. Plots of DD (derived from heavily filtered flow curves) vs. lung inflation showed an unambiguous value for VisoV.

Adolescent↗
PubMed1987

Lung volumes in Polynesian children.

Polynesian (Maori and Pacific Island) children account for approximately one quarter of the children in New Zealand, but good data for lung function in this group are not available. In this review, we report lung volume measurements in 571 healthy children 5 to 13 yr of age: 270 Polynesians (139 boys and 131 girls) and 301 Europeans (177 boys and 124 girls). All measurements were made in a body plethysmograph. Polynesian boys had significantly larger VC, FVC, FRC, TLC, and expiratory reserve volume than did Polynesian girls. Polynesian and European children generally showed different slope and intercept relationships for the prediction of lung volume from height. Racial differences are not adequately explained by differences in body proportions or social factors including parental smoking. Possible explanations include racial differences in lung growth and maturation.

Adolescent↗
PubMed1985

A comparison of inhaled powders of fenoterol and salbutamol in asthma.

The present study compares fenoterol and salbutamol powders (0.2 mg). Twenty-five children with frequent episodic asthma, aged 4-9 years, entered a double-blind, randomized, crossover, placebo controlled study. On each of three days fenoterol, salbutamol or placebo were given in random order. Lung function testing and other observations were made before and at set intervals up to 4 h after the treatments. Both inhaled powders increased the forced expired volume in 1 s and the maximum mid-expiratory flow rate significantly above placebo effect. No side effects were observed and there were no significant differences in bronchodilator efficacy between fenoterol and salbutamol.

Albuterol↗
PubMed1983

Histamine inhalation challenge in children: a comparison of two methods.

Airway reactivity in children is often assessed using a histamine inhalation challenge test. The bronchoconstrictor agents are usually delivered by five slow inspiratory capacity (IC) maneuvers, the IC method. We compared the IC method with a tidal breathing (TB) method in 30 children; 11 were normal, six were under investigation for asthma and 13 were known asthmatics. None of the normal children responded to either method, whereas 18 out of the 19 (95%) known or suspected asthmatics responded to the TB method while only 13 out of 19 (68%) showed a significant reduction in FEV1 when the IC method was used. The concentration of histamine necessary to cause a 20% reduction in FEV1 was less for the TB method, suggesting that in children the TB method will produce airway reactivity more quickly than the IC method.

Adolescent↗