Malcolm R. Sears

Epidemiology of childhood asthma

populations in epidemiological studies was proposed by Toelle et al, who reported “current asthma” if the patient had had symptoms (wheezing, chest tightness, recurrent cough) in the previous 12 months and had a positive airway responsiveness test. Patients fulfilling these criteria had more symptoms, greater variability in flow rates, more atopy, and required more treatment than those with symptoms but not airway responsiveness or the small group with airway responsiveness and no symptoms. The International Study of Asthma and Allergies in Childhood (ISAAC), a worldwide study of the prevalence of childhood asthma and respiratory symptoms in the age-groups 6–7 years and 13–14 years, has brought uniformity into data collection, as far as language allows. Prevalence rates for wheezing among 13–14-year-olds reported from representative countries are shown in panel 2. Phase 2 of ISAAC will include measurements of lung function, airway responsiveness, and atopy which will further help elucidate differences and similarities among populations.

The β2-Agonist Controversy

SummaryLinks between frequent use of inhaled β2-agonists and morbidity and mortality from asthma appear probable. Two mortality epidemics followed the marketing of potent inhaled adrenergic agents. Case-control studies in New Zealand linked mortality with prescription of fenoterol, especially in severe asthma. A Saskatchewan case-control study confirmed an association of mortality with fenoterol, and also with frequent use of salbutamol (albuterol). Cardiac effects of β2-agonists do not cause mortality, but frequent use of these agents may increase the chronic severity of asthma, hence increasing the number of asthmatic patients at risk of death in an acute attack. Frequent use of β2-agonists may reduce lung function, increasing airway responsiveness, and impair control of asthma, despite use of inhaled corticosteroids. Mechanisms for this effect may include tachyphylaxis to nonbronchodilator effects, increased responsiveness to allergen, interaction with corticosteroid receptors, altered mucociliary function, differential effects of enantiomers, and masking of symptoms by β2-agonist use. The withdrawal of fenoterol from New Zealand in 1990 was associated with a substantial decline in morbidity and mortality.Overall, the evidence suggests that frequent use of inhaled β2-agonists has a deleterious effect on the control of asthma. Epidemics of mortality are explained by an increase in chronic severity of asthma following introduction of more potent β2-agonists. While β2-agonists remain essential for relief of breakthrough symptoms, long term use, particularly with high doses of potent agents, appears to be detrimental.

Allergic disorders and attention deficit disorder in children

It has been suggested that children with attention deficit disorder-hyperactivity (ADDH) are likely to show allergic disorders, and that both ADDH and allergic disorders may share a common biological background. In a large sample of children from the general population we found no association between parent, teacher, and self-reports of ADDH behaviors and a history of allergic disorders (asthma, eczema, rhinitis, and urticaria) at ages 9 or 13 years. Similarly, reports of ADDH behaviors at age 13 years were not related to level of atopic responsiveness by skin test or serum IgE levels. Our findings call into question the hypothesis that there is a relationship between ADDH and allergic disorder.

The definition and diagnosis of asthma

Asthma defies precise definition, despite several carefully worded statements. Perhaps the most concise and useful description of asthma is “variable airflow obstruction”. The diagnosis is made by recognition of a patterns of one or more characteristic symptoms including wheeze, cough, chest tightness and dyspnoea, and is best confirmed by evidence of variable or reversible airflow obstruction accompanying symptoms.

Trends in asthma mortality in young people in southern Brazil

BACKGROUND Mortality from asthma increased and is now declining in some countries, but little is known about these trends in South America. OBJECTIVE We aimed to assess trends in mortality from asthma in southern Brazil in children and young adults. METHODS Death certificates of 425 people in the state of Rio Grande do Sul aged between 5 and 39 years in whom asthma was reported to be the underlying cause of death during the period 1970 to 1992 were reviewed. Population data were available in 10-year age groups. Testing for trends in mortality rates was conducted using linear and log-linear regression procedures. RESULTS Asthma mortality rates in the age groups 5 to 19 and 20 to 39 years ranged between 0.04 and 0.39/100,000 and 0.28 to 0.75/100,000, respectively, and were nonuniformly distributed over the study period. The mean annual increase in rate in 5- to 19-year olds was +0.01 (95% CI 0.003 to 0.016), an average annual percentage increase of +6.8% (95% CI 3% to 11%), with a total increase of 352% between 1970 and 1992. This increase was not due to a shift in labeling from bronchitis to asthma. In the 20 to 39-year age group, asthma and bronchitis mortality rates showed no trend to increase or decrease. CONCLUSIONS Asthma mortality in southern Brazil is low, but rose significantly between 1970 and 1992 in the 5 to 19-year age group. This trend differs from that found in other states of Brazil and several other Latin American countries. Reasons for this difference remain unclear.

Asthma Mortality in Southern Brazil: Is There a Changing Trend?

Background. Mortality from asthma increased during the last decades but is now declining in some countries. Little is known about this trend in Brazil. Objective. The objective of the study was to determine the trends in asthma mortality in Southern Brazil. Methods. We reviewed death certificates of 566 people in the state of Rio Grande do Sul, Brazil, between 5 and 39 years of age in whom asthma was reported to be the underlying cause of death during the period of 1981-2003. Population data were available in 5-year age groups. Mortality rates were submitted to linear and quadratic regression procedures. Results. Among children and teenagers (5–19 years), there were 170 asthma deaths, ranging from 4 to 13 deaths each year with rates of 0.154/100,000 to 0.481/100,000. In young adults (20–39 years), 396 asthma deaths occurred, ranging from 9 to 32 each year, with rates from 0.276/100,000 to 1.034/100,000. There was an initial increase in rates, with later stabilization, and then the start of a decline beginning in the late 1990s and the early part of this decade. This trend occurred in both age subgroups examined but was more evident in males. Conclusions. Asthma mortality in southern Brazil remains low and appears to be decreasing after reaching a peak in the mid-1990s. The reason for these trends remains unknown.

Are inhaled longacting β2 agonists detrimental to asthma

Possible adverse effects of adrenergic bronchodilators in asthma have been the subject of discussion for more than half a century, with recent intense debate about the safety of longacting β agonists (LABAs). In this Debate, we consider the issues of bronchodilator and bronchoprotective tolerance resulting from the frequent use of bronchodilators, which is noted particularly with shortacting drugs, but has also been shown to occur quicker and to a greater extent with LABAs. Increased allergen responsiveness and masking allowing inflammation to increase, while symptoms and lung function remain apparently controlled, have also been observed. Studies in which LABAs were used as monotherapy were associated with increased mortality. However, several studies have shown the benefits of adding LABAs to inhaled corticosteroids (ICS). Meta-analyses of asthma clinical trials involving LABAs showed that, when given with mandatory ICS, LABAs were not associated with an increased risk of death, intubations, or hospital admission for exacerbations when compared with use of the same dose of ICS only. Withdrawal of LABA therapy once symptom control is achieved is often associated with subsequent loss of symptom control. When used for appropriate indications, LABAs should be combined with ICS in one inhaler so that monotherapy is not possible.