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.

Worldwide trends in the prevalence of asthma symptoms: phase III of the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND

Phase I of the International Study of Asthma and Allergies in Childhood (ISAAC) was designed to allow worldwide comparisons of the prevalence of asthma symptoms. In phase III the phase I survey was repeated in order to assess changes over time.

METHODS

The phase I survey was repeated after an interval of 5-10 years in 106 centres in 56 countries in children aged 13-14 years (n = 304,679) and in 66 centres in 37 countries in children aged 6-7 years (n = 193,404).

RESULTS

The mean symptom prevalence of current wheeze in the last 12 months changed slightly from 13.2% to 13.7% in the 13-14 year age group (mean increase of 0.06% per year) and from 11.1% to 11.6% in the 6-7 year age group (mean increase of 0.13% per year). There was also little change in the mean symptom prevalence of severe asthma or the symptom prevalence measured with the asthma video questionnaire. However, the time trends in asthma symptom prevalence showed different regional patterns. In Western Europe, current wheeze decreased by 0.07% per year in children aged 13-14 years but increased by 0.20% per year in children aged 6-7 years. The corresponding findings per year for the other regions in children aged 13-14 years and 6-7 years, respectively, were: Oceania (-0.39% and -0.21%); Latin America (+0.32% and +0.07%); Northern and Eastern Europe (+0.26% and +0.05%); Africa (+0.16% and +0.10%); North America (+0.12% and +0.32%); Eastern Mediterranean (-0.10% and +0.79%); Asia-Pacific (+0.07% and -0.06%); and the Indian subcontinent (+0.02% and +0.06%). There was a particularly marked reduction in current asthma symptom prevalence in English language countries (-0.51% and -0.09%). Similar patterns were observed for symptoms of severe asthma. However, the percentage of children reported to have had asthma at some time in their lives increased by 0.28% per year in the 13-14 year age group and by 0.18% per year in the 6-7 year age group.

CONCLUSIONS

These findings indicate that international differences in asthma symptom prevalence have reduced, particularly in the 13-14 year age group, with decreases in prevalence in English speaking countries and Western Europe and increases in prevalence in regions where prevalence was previously low. Although there was little change in the overall prevalence of current wheeze, the percentage of children reported to have had asthma increased significantly, possibly reflecting greater awareness of this condition and/or changes in diagnostic practice. The increases in asthma symptom prevalence in Africa, Latin America and parts of Asia indicate that the global burden of asthma is continuing to rise, but the global prevalence differences are lessening.

Cellular events in the bronchi in mild asthma and after bronchial provocation

We have undertaken detailed cellular and ultrastructural examination of bronchial biopsies and bronchial lavage fluid from allergic asthmatic patients in order to determine the nature and degree of the inflammatory processes in mild allergic asthma. Eight atopic asthmatic patients (mean PC20 histamine, 0.90 mg/ml) and four nonasthmatic control subjects underwent fiberoptic bronchoscopy. All asthmatic subjects were clinically stable for 2 wk prior to bronchoscopy and required either no treatment or inhaled albuterol alone. A single 50-ml bronchial wash was undertaken, followed by endobronchial biopsy of subcarinae. These procedures were repeated in the asthmatic subjects 18 h after bronchial provocation with allergen or methacholine. Subsequently, all subjects underwent bronchial reactivity testing with inhaled histamine. The clinical and physiologic data were not revealed to the pathologist interpreting the specimens. The asthmatic subjects shed a significantly greater number of epithelial cells into the lavage fluid than did the nonasthmatic subjects (7.23 versus 1.48 x 10(4)/ml, p = 0.048). There was a statistically significant inverse correlation between the lavage epithelial cell count and bronchial reactivity (rho = -0.64, p = 0.03). In the asthmatic subjects, but not in the control subjects, there was extensive deposition of collagen beneath the epithelial basement membrane, mast cell degranulation, and mucosal infiltration by eosinophils, which exhibited morphologic evidence of activation. Eosinophils, monocytes, and platelets were found in contact with the vascular endothelium, with emigration of eosinophils and monocytes in the asthmatic subjects. These changes were found irrespective of bronchial challenge with allergen. We conclude that allergic asthma is accompanied by extensive inflammatory changes in the airways, even in mild clinical and subclinical disease.

Benefits of omalizumab as add-on therapy in patients with severe persistent asthma who are inadequately controlled despite best available therapy (GINA 2002 step 4 treatment): INNOVATE

BACKGROUND

Patients with severe persistent asthma who are inadequately controlled despite Global Initiative for Asthma (GINA) 2002 step 4 therapy are a challenging population with significant unmet medical need. We determined the effect of omalizumab on clinically significant asthma exacerbations (requiring systemic corticosteroids) in the first omalizumab study to exclusively enrol patients from this difficult-to-treat patient population.

METHODS

Following a run-in phase, patients (12-75 years) inadequately controlled despite therapy with high-dose inhaled corticosteroids (ICS) and long-acting beta(2)-agonists (LABA) with reduced lung function and a recent history of clinically significant exacerbations were randomized to receive omalizumab or placebo for 28 weeks in a double-blind, parallel-group, multicentre study.

RESULTS

A total of 419 patients were included in the efficacy analyses. The clinically significant asthma exacerbation rate (primary efficacy variable), adjusted for an observed relevant imbalance in history of clinically significant asthma exacerbations, was 0.68 with omalizumab and 0.91 with placebo (26% reduction) during the 28-week treatment phase (P = 0.042). Without adjustment, a similar magnitude of effect was seen (19% reduction), but this did not reach statistical significance. Omalizumab significantly reduced severe asthma exacerbation rate (0.24 vs 0.48, P = 0.002) and emergency visit rate (0.24 vs 0.43, P = 0.038). Omalizumab significantly improved asthma-related quality of life, morning peak expiratory flow and asthma symptom scores. The incidence of adverse events was similar between treatment groups.

CONCLUSIONS

In patients with inadequately controlled severe persistent asthma, despite high-dose ICS and LABA therapy, and often additional therapy, omalizumab significantly reduced the rate of clinically significant asthma exacerbations, severe exacerbations and emergency visits. Omalizumab is effective and should be considered as add-on therapy for patients with inadequately controlled severe persistent asthma who have a significant unmet need despite best available therapy.

Subepithelial fibrosis in the bronchi of asthmatics

The epithelial basement membrane and underlying collagen were examined by immunohistochemistry and electron microscopy in endobronchial biopsy specimens from 8 asthmatic and 3 control subjects. There was an excess of interstitial collagens beneath the basement membrane in the asthmatic subjects. There was no evidence of any epithelial contribution to this abnormality, nor was there any correlation with epithelial damage, disease duration, or severity. These findings contradict the long-held notion of basement membrane thickening in asthma and indicate that the subepithelial fibrosis is a result of fibroblast activation rather than bronchial epithelial cell dysfunction.

Treatable traits: toward precision medicine of chronic airway diseases

Asthma and chronic obstructive pulmonary disease (COPD) are two prevalent chronic airway diseases that have a high personal and social impact. They likely represent a continuum of different diseases that may share biological mechanisms (i.e. endotypes), and present similar clinical, functional, imaging and/or biological features that can be observed (i.e. phenotypes) which require individualised treatment. Precision medicine is defined as "treatments targeted to the needs of individual patients on the basis of genetic, biomarker, phenotypic, or psychosocial characteristics that distinguish a given patient from other patients with similar clinical presentations". In this Perspective, we propose a precision medicine strategy for chronic airway diseases in general, and asthma and COPD in particular.

Global variation in the prevalence and severity of asthma symptoms: phase three of the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND

Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC) measured the global prevalence and severity of asthma symptoms in children.

METHODS

A cross-sectional questionnaire survey of 798 685 children aged 13-14 years from 233 centres in 97 countries, and 388 811 children aged 6-7 years from 144 centres in 61 countries, was conducted between 2000 and 2003 in >90% of the centres.

RESULTS

The prevalence of wheeze in the past 12 months (current wheeze) ranged from 0.8% in Tibet (China) to 32.6% in Wellington (New Zealand) in the 13-14 year olds, and from 2.4% in Jodhpur (India) to 37.6% in Costa Rica in the 6-7 year olds. The prevalence of symptoms of severe asthma, defined as >or=4 attacks of wheeze or >or=1 night per week sleep disturbance from wheeze or wheeze affecting speech in the past 12 months, ranged from 0.1% in Pune (India) to 16% in Costa Rica in the 13-14 year olds and from 0% to 20.3% in the same two centres, respectively, in the 6-7 year olds. Ecological economic analyses revealed a significant trend towards a higher prevalence of current wheeze in centres in higher income countries in both age groups, but this trend was reversed for the prevalence of severe symptoms among current wheezers, especially in the older age group.

CONCLUSION

Wide variations exist in the symptom prevalence of childhood asthma worldwide. Although asthma symptoms tend to be more prevalent in more affluent countries, they appear to be more severe in less affluent countries.

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.

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial

Importance

Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited.

Objective

To determine whether hydrocortisone improves outcome for patients with severe COVID-19.

Design, Setting, and Participants

An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020.

Interventions

The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108).

Main Outcomes and Measures

The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%).

Results

After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively.

Conclusions and Relevance

Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions.

Trial Registration

ClinicalTrials.gov Identifier: NCT02735707.

Effect of a Buffered Crystalloid Solution vs Saline on Acute Kidney Injury Among Patients in the Intensive Care Unit: The SPLIT Randomized Clinical Trial

IMPORTANCE

Saline (0.9% sodium chloride) is the most commonly administered intravenous fluid; however, its use may be associated with acute kidney injury (AKI) and increased mortality.

OBJECTIVE

To determine the effect of a buffered crystalloid compared with saline on renal complications in patients admitted to the intensive care unit (ICU).

DESIGN AND SETTING

Double-blind, cluster randomized, double-crossover trial conducted in 4 ICUs in New Zealand from April 2014 through October 2014. Three ICUs were general medical and surgical ICUs; 1 ICU had a predominance of cardiothoracic and vascular surgical patients.

PARTICIPANTS

All patients admitted to the ICU requiring crystalloid fluid therapy were eligible for inclusion. Patients with established AKI requiring renal replacement therapy (RRT) were excluded. All 2278 eligible patients were enrolled; 1152 of 1162 patients (99.1%) receiving buffered crystalloid and 1110 of 1116 patients (99.5%) receiving saline were analyzed.

INTERVENTIONS

Participating ICUs were assigned a masked study fluid, either saline or a buffered crystalloid, for alternating 7-week treatment blocks. Two ICUs commenced using 1 fluid and the other 2 commenced using the alternative fluid. Two crossovers occurred so that each ICU used each fluid twice over the 28 weeks of the study. The treating clinician determined the rate and frequency of fluid administration.

MAIN OUTCOMES AND MEASURES

The primary outcome was proportion of patients with AKI (defined as a rise in serum creatinine level of at least 2-fold or a serum creatinine level of ≥3.96 mg/dL with an increase of ≥0.5 mg/dL); main secondary outcomes were incidence of RRT use and in-hospital mortality.

RESULTS

In the buffered crystalloid group, 102 of 1067 patients (9.6%) developed AKI within 90 days after enrollment compared with 94 of 1025 patients (9.2%) in the saline group (absolute difference, 0.4% [95% CI, -2.1% to 2.9%]; relative risk [RR], 1.04 [95% CI, 0.80 to 1.36]; P = .77). In the buffered crystalloid group, RRT was used in 38 of 1152 patients (3.3%) compared with 38 of 1110 patients (3.4%) in the saline group (absolute difference, -0.1% [95% CI, -1.6% to 1.4%]; RR, 0.96 [95% CI, 0.62 to 1.50]; P = .91). Overall, 87 of 1152 patients (7.6%) in the buffered crystalloid group and 95 of 1110 patients (8.6%) in the saline group died in the hospital (absolute difference, -1.0% [95% CI, -3.3% to 1.2%]; RR, 0.88 [95% CI, 0.67 to 1.17]; P = .40).

CONCLUSIONS AND RELEVANCE

Among patients receiving crystalloid fluid therapy in the ICU, use of a buffered crystalloid compared with saline did not reduce the risk of AKI. Further large randomized clinical trials are needed to assess efficacy in higher-risk populations and to measure clinical outcomes such as mortality.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: ACTRN12613001370796.

Worldwide variations in prevalence of symptoms of allergic rhinoconjunctivitis in children: the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND

As part of the International Study of Asthma and Allergies in Childhood (ISAAC), prevalence surveys were conducted among representative samples of school children from locations in Europe, Asia, Africa, Australia, North and South America.

SUBJECTS

257,800 children aged 6-7 years from 91 centres in 38 countries, and 463,801 children aged 13-14 years from 155 centres in 56 countries.

METHODS

Written symptom questionnaires were translated from English into the local language for self-completion by the 13-14-year-olds and completion by the parents of the 6-7-year-olds. Rhinitis was described as a problem with sneezing, or a runny, or blocked nose when you (your child) DID NOT have a cold or the flu. Additional questions were asked about rhinitis associated with itchy-watery eyes, interference with activities and a history of hay fever ever.

RESULTS

The prevalence of rhinitis with itchy-watery eyes ("rhinoconjunctivitis") in the past year varied across centres from 0.8% to 14.9% in the 6-7-year-olds and from 1.4% to 39.7% in the 13-14-year-olds. Within each age group, the global pattern was broadly consistent across each of the symptom categories. In centres of higher prevalence there was great variability in the proportion of rhinoconjunctivitis labelled as hay fever. The lowest prevalences of rhinoconjunctivitis were found in parts of eastern Europe, south and central Asia. High prevalences were reported from centres in several regions.

CONCLUSION

These results suggest substantial worldwide variations in the prevalence and labelling of symptoms of allergic rhinoconjunctivitis which require further study. These differences, if real, may offer important clues to environmental influences on allergy.

Prescribed fenoterol and death from asthma in New Zealand, 1981-83: case-control study

A case-control study was conducted to examine the hypothesis that fenoterol by metered dose inhaler (MDI) increases the risk of death in patients with asthma. The case group comprised 117 patients aged 5-45 who died of asthma between August, 1981, and July, 1983. For each case, 4 controls, matched for age and ethnic group, were selected from asthma admissions to hospitals to which the cases themselves would have been admitted, had they survived. The relative risk of asthma death in patients prescribed fenoterol by MDI was 1.55 (95% CI 1.04-2.33, p = 0.03). The possibility of confounding or effect modification by severity was assessed by consideration of subgroups defined by markers of asthma severity. The fenoterol MDI relative risk was 2.21 (95% CI 1.26-3.88, p = 0.01) in patients prescribed three or more categories of asthma drugs, 2.16 (95% CI 1.14-4.11, p = 0.02) in patients with a hospital admission for asthma during the previous 12 months, and 6.45 (95% CI 2.72-15.3, p less than 0.01) in patients prescribed oral corticosteroids at time of death or admission. In the group of patients with the most severe asthma (defined by a hospital admission during the previous year and prescription of oral corticosteroids) the fenoterol MDI relative risk was 13.29 (95% CI 3.45-51.2, p less than 0.01). After adjustment for severity, no other asthma treatment commonly used in New Zealand seemed to be associated with an increased risk of asthma death. Not all sources of bias can be definitely excluded; however, when considered together with other epidemiological and experimental evidence, these findings are consistent with the hypothesis that use of fenoterol by MDI increases the risk of death in severe asthma.

Risk factors for asthma: is prevention possible?

Asthma is one of the most common diseases in the world, resulting in a substantial burden of disease. Although rates of deaths due to asthma worldwide have reduced greatly over the past 25 years, no available therapeutic regimens can cure asthma, and the burden of asthma will continue to be driven by increasing prevalence. The reasons for the increase in asthma prevalence have not been defined, which limits the opportunities to develop targeted primary prevention measures. Although associations are reported between a wide range of risk factors and childhood asthma, substantiation of causality is inherently difficult from observational studies, and few risk factors have been assessed in primary prevention studies. Furthermore, none of the primary prevention intervention strategies that have undergone scrutiny in randomised controlled trials has provided sufficient evidence to lead to widespread implementation in clinical practice. A better understanding of the factors that cause asthma is urgently needed, and this knowledge could be used to develop public health and pharmacological primary prevention measures that are effective in reducing the prevalence of asthma worldwide. To achieve this it will be necessary to think outside the box, not only in terms of risk factors for the causation of asthma, but also the types of novel primary prevention strategies that are developed, and the research methods used to provide the evidence base for their implementation. In the interim, public health efforts should remain focused on measures with the potential to improve lung and general health, such as: reducing tobacco smoking and environmental tobacco smoke exposure; reducing indoor and outdoor air pollution and occupational exposures; reducing childhood obesity and encouraging a diet high in vegetables and fruit; improving feto-maternal health; encouraging breastfeeding; promoting childhood vaccinations; and reducing social inequalities.

Conservative Oxygen Therapy during Mechanical Ventilation in the ICU

BACKGROUND

Patients who are undergoing mechanical ventilation in the intensive care unit (ICU) often receive a high fraction of inspired oxygen (Fio₂) and have a high arterial oxygen tension. The conservative use of oxygen may reduce oxygen exposure, diminish lung and systemic oxidative injury, and thereby increase the number of ventilator-free days (days alive and free from mechanical ventilation).

METHODS

We randomly assigned 1000 adult patients who were anticipated to require mechanical ventilation beyond the day after recruitment in the ICU to receive conservative or usual oxygen therapy. In the two groups, the default lower limit for oxygen saturation as measured by pulse oximetry (Spo₂) was 90%. In the conservative-oxygen group, the upper limit of the Spo₂ alarm was set to sound when the level reached 97%, and the Fio₂ was decreased to 0.21 if the Spo₂ was above the acceptable lower limit. In the usual-oxygen group, there were no specific measures limiting the Fio₂ or the Spo₂. The primary outcome was the number of ventilator-free days from randomization until day 28.

RESULTS

The number of ventilator-free days did not differ significantly between the conservative-oxygen group and the usual-oxygen group, with a median duration of 21.3 days (interquartile range, 0 to 26.3) and 22.1 days (interquartile range, 0 to 26.2), respectively, for an absolute difference of -0.3 days (95% confidence interval [CI], -2.1 to 1.6; P = 0.80). The conservative-oxygen group spent more time in the ICU with an Fio₂ of 0.21 than the usual-oxygen group, with a median duration of 29 hours (interquartile range, 5 to 78) and 1 hour (interquartile range, 0 to 17), respectively (absolute difference, 28 hours; 95% CI, 22 to 34); the conservative-oxygen group spent less time with an Spo₂ exceeding 96%, with a duration of 27 hours (interquartile range, 11 to 63.5) and 49 hours (interquartile range, 22 to 112), respectively (absolute difference, 22 hours; 95% CI, 14 to 30). At 180 days, mortality was 35.7% in the conservative-oxygen group and 34.5% in the usual-oxygen group, for an unadjusted odds ratio of 1.05 (95% CI, 0.81 to 1.37).

CONCLUSIONS

In adults undergoing mechanical ventilation in the ICU, the use of conservative oxygen therapy, as compared with usual oxygen therapy, did not significantly affect the number of ventilator-free days. (Funded by the Health Research Council of New Zealand; ICU-ROX Australian and New Zealand Clinical Trials Registry number, ACTRN12615000957594.).

Prevalence and etiology of asthma

An increased understanding of the causes of asthma is coming from the international comparisons of asthma prevalence, particularly those from the European Community Respiratory Health Survey of asthma prevalence in adults and the International Study of Asthma and Allergies in Childhood. From these and other studies of asthma prevalence, it is possible to draw some tentative conclusions as to the patterns of asthma prevalence worldwide. There are five striking patterns: first, asthma prevalence is increasing worldwide; second, asthma is generally more common in Western countries and less common in developing countries; third, asthma is more prevalent in English-speaking countries; fourth, asthma prevalence is increasing in developing countries as they become more Westernized or communities become urbanized; and fifth, the prevalence of other allergic disorders may also be increasing worldwide. These five key features of the international patterns of asthma prevalence raise major questions about the role of "established" risk factors for the development of asthma. As a result, recent research has expanded to include the study of novel factors that may "program" the initial susceptibility to sensitization or contribute to the development of asthma independent of atopic sensitization. These include various exposures in utero, which are reflected in various perinatal factors measured at birth, and exposures (or lack of exposures) in the early years of life that may make the infant more susceptible to the subsequent development of asthma. These issues are now the focus of an intensive research effort worldwide, and the next few years are likely to see exciting advances in our understanding of the causes of asthma.

Controlled Trial of Budesonide-Formoterol as Needed for Mild Asthma

BACKGROUND

In double-blind, placebo-controlled trials, budesonide-formoterol used on an as-needed basis resulted in a lower risk of severe exacerbation of asthma than as-needed use of a short-acting β₂-agonist (SABA); the risk was similar to that of budesonide maintenance therapy plus as-needed SABA. The availability of data from clinical trials designed to better reflect clinical practice would be beneficial.

METHODS

We conducted a 52-week, randomized, open-label, parallel-group, controlled trial involving adults with mild asthma. Patients were randomly assigned to one of three treatment groups: albuterol (100 μg, two inhalations from a pressurized metered-dose inhaler as needed for asthma symptoms) (albuterol group); budesonide (200 μg, one inhalation through a Turbuhaler twice daily) plus as-needed albuterol (budesonide maintenance group); or budesonide-formoterol (200 μg of budesonide and 6 μg of formoterol, one inhalation through a Turbuhaler as needed) (budesonide-formoterol group). Electronic monitoring of inhalers was used to measure medication use. The primary outcome was the annualized rate of asthma exacerbations.

RESULTS

The analysis included 668 of 675 patients who underwent randomization. The annualized exacerbation rate in the budesonide-formoterol group was lower than that in the albuterol group (absolute rate, 0.195 vs. 0.400; relative rate, 0.49; 95% confidence interval [CI], 0.33 to 0.72; P<0.001) and did not differ significantly from the rate in the budesonide maintenance group (absolute rate, 0.195 in the budesonide-formoterol group vs. 0.175 in the budesonide maintenance group; relative rate, 1.12; 95% CI, 0.70 to 1.79; P = 0.65). The number of severe exacerbations was lower in the budesonide-formoterol group than in both the albuterol group (9 vs. 23; relative risk, 0.40; 95% CI, 0.18 to 0.86) and the budesonide maintenance group (9 vs. 21; relative risk, 0.44; 95% CI, 0.20 to 0.96). The mean (±SD) dose of inhaled budesonide was 107±109 μg per day in the budesonide-formoterol group and 222±113 μg per day in the budesonide maintenance group. The incidence and type of adverse events reported were consistent with those in previous trials and with reports in clinical use.

CONCLUSIONS

In an open-label trial involving adults with mild asthma, budesonide-formoterol used as needed was superior to albuterol used as needed for the prevention of asthma exacerbations. (Funded by AstraZeneca and the Health Research Council of New Zealand; Novel START Australian New Zealand Clinical Trials Registry number, ACTRN12615000999538.).

Prescribed fenoterol and death from asthma in New Zealand, 1981-7: a further case-control study

The association between inhaled fenoterol and death from asthma has been investigated further by studying 112 asthma deaths (cases) during 1981-7 in patients aged 5-45 years who had been admitted to a major hospital for asthma during the 12 months before death. Two age matched control groups were chosen. Control group A comprised 427 patients who had been admitted to hospital for asthma during the calendar year that the corresponding death occurred and who had also had a previous admission for asthma in the previous 12 months. Control group B comprised 448 patients admitted to hospital for asthma during the calendar year in which the admission of the corresponding case occurred. The inhaled fenoterol odds ratio was 2.11 (95% confidence interval (CI) 1.37-3.23, p less than 0.01) when group A was used as the control (the approach used in previous studies), and 2.66 (95% CI 1.74-4.06, p less than 0.01) with group B as the control (the approach recommended by critics of previous studies). Markers of chronic asthma severity were associated with asthma death when control group B was used, but not when control group A was used (which indicates that these markers were indirectly matched for when control group A was used). Information was also collected on various markers of acute asthma severity and prescription of psychotropic drugs, but it was found that these were not important confounders. These findings address the major criticisms of previous case-control studies of this issue, and add support to the hypothesis that inhaled fenoterol increases the risk of death in patients with severe asthma.

Case-control study of prescribed fenoterol and death from asthma in New Zealand, 1977-81

A previous New Zealand case-control study of asthma deaths in the 5-45 year age group during 1981-3 found that prescription of fenoterol (by metered dose inhaler) was associated with an increased risk of death in patients with severe asthma. One major criticism of this study was that drug data for the cases and controls came from different sources. A new case-control design has been used to evaluate the same hypothesis, with a different set of asthma deaths, the same source for drug information being used for both cases and controls. This depended on identifying deaths from asthma during 1977-81 from national mortality records, and ascertaining which patients from those who died had been admitted to a major hospital for asthma during the 12 months before death. The study was confined to this subgroup, which accounted for about 20% of all asthma deaths in the areas served by a major hospital. For each of the eligible patients who died four age matched controls were selected from patients admitted to hospital for asthma during the year that the death occurred who had also had an admission for asthma in the previous 12 months. For the 58 cases and 227 control subjects information on prescribed drugs was collected from the hospital records relating to the previous admission. The odds ratio of asthma death in patients prescribed inhaled fenoterol was 1.99 (95% confidence interval 1.12-3.55, p = 0.02). As in the previous study, subgroups defined by markers of chronic asthma severity were also considered. The inhaled fenoterol odds ratio was 2.98 (95% CI 1.15-7.70, p = 0.02) in patients prescribed three or more categories of asthma drugs, 3.91 (95% CI 1.79-8.54, p less than 0.01) in patients with a previous admission for asthma in the past 12 months, and 5.83 (95% CI 1.62-21.0, p = 0.01) in patients prescribed oral corticosteroids at the time of admission. In patients with the most severe asthma (defined by a previous admission for asthma during the past 12 months and prescribed oral corticosteroids at time of admission) the inhaled fenoterol odds ratio was 9.82 (95% CI 2.23-43.4, p less than 0.01). These findings add further support to the hypothesis that inhaled fenoterol increases the risk of death in patients with severe asthma.

External validity of randomised controlled trials in asthma: to whom do the results of the trials apply?

BACKGROUND

Asthma is a heterogeneous disease with a wide range of clinical phenotypes, not all of which may be encompassed in the subjects included in randomised controlled trials (RCTs). This makes it difficult for clinicians to know to what extent the evidence derived from RCTs applies to a given patient.

AIM

To calculate the proportion of individuals with asthma who would have been eligible for the major asthma RCTs from the data of a random community survey of respiratory health.

METHODS

A postal survey was sent to 3500 randomly selected individuals aged 25-75 years. Respondents were invited to complete a detailed respiratory questionnaire and pulmonary function testing. Participants with current asthma were assessed against the eligibility criteria of the 17 major asthma RCTs cited in the Global Initiative for Asthma (GINA) guidelines.

FINDINGS

A total of 749 participants completed the full survey, of whom 179 had current asthma. A median 4% of participants with current asthma (range 0-36%) met the eligibility criteria for the included RCTs. A median 6% (range 0-43%) of participants with current asthma on treatment met the eligibility criteria.

INTERPRETATION

This study shows that the major asthma RCTs on which the GINA guidelines are based may have limited external validity as they have been performed on highly selected patient populations. Most of the participants with current asthma on treatment in the community would not have been eligible for these RCTs.

Association between paracetamol use in infancy and childhood, and risk of asthma, rhinoconjunctivitis, and eczema in children aged 6-7 years: analysis from Phase Three of the ISAAC programme

BACKGROUND

Exposure to paracetamol during intrauterine life, childhood, and adult life may increase the risk of developing asthma. We studied 6-7-year-old children from Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC) programme to investigate the association between paracetamol consumption and asthma.

METHODS

As part of Phase Three of ISAAC, parents or guardians of children aged 6-7 years completed written questionnaires about symptoms of asthma, rhinoconjunctivitis, and eczema, and several risk factors, including the use of paracetamol for fever in the child's first year of life and the frequency of paracetamol use in the past 12 months. The primary outcome variable was the odds ratio (OR) of asthma symptoms in these children associated with the use of paracetamol for fever in the first year of life, as calculated by logistic regression.

FINDINGS

205 487 children aged 6-7 years from 73 centres in 31 countries were included in the analysis. In the multivariate analyses, use of paracetamol for fever in the first year of life was associated with an increased risk of asthma symptoms when aged 6-7 years (OR 1.46 [95% CI 1.36-1.56]). Current use of paracetamol was associated with a dose-dependent increased risk of asthma symptoms (1.61 [1.46-1.77] and 3.23 [2.91-3.60] for medium and high use vs no use, respectively). Use of paracetamol was similarly associated with the risk of severe asthma symptoms, with population-attributable risks between 22% and 38%. Paracetamol use, both in the first year of life and in children aged 6-7 years, was also associated with an increased risk of symptoms of rhinoconjunctivitis and eczema.

INTERPRETATION

Use of paracetamol in the first year of life and in later childhood, is associated with risk of asthma, rhinoconjunctivitis, and eczema at age 6 to 7 years. We suggest that exposure to paracetamol might be a risk factor for the development of asthma in childhood.

A self management plan in the treatment of adult asthma

To determine whether routine assessment of peak expiratory flow (PEF) in association with a self management plan based on inhaled corticosteroid use is effective in the management of chronic asthma, 36 consecutive adult patients with asthma attending an outpatient chest clinic were admitted to an open prospective study. Patients were treated with inhaled salbutamol and beclomethasone dipropionate in an attempt to achieve normal lung function. Each patient had a "potential normal value," which was either the predicted normal or the maximum PEF value achieved by the patient, whichever was the higher. Patients measured PEF at home and if it fell by more than 30% from the potential normal value the dose of beclomethasone was doubled until PEF returned to the potential normal value, then continued at 20 mg/day for the same number of days. If PEF fell to below 150-200 l/min patients were asked to obtain emergency medical assistance. In the 30 patients who completed the trial the six months before and the six months after intervention with the self management plan were compared. There was a substantial improvement in both subjective and objective measurements of asthma severity, with a significant reduction in nights woken, days lost from work, and requirement for oral corticosteroids and a significant increase in baseline lung function. Routine measurement of PEF in association with a self management plan appears to be effective in reducing symptoms of asthma and improving lung function.