How to choose your study design

Research designs are broadly divided into observational studies (i.e. cross-sectional; case-control and cohort studies) and experimental studies (randomised control trials, RCTs). Each design has a specific role, and each has both advantages and disadvantages. Moreover, while the typical RCT is a parallel group design, there are now many variants to consider. It is important that both researchers and paediatricians are aware of the role of each study design, their respective pros and cons, and the inherent risk of bias with each design. While there are numerous quantitative study designs available to researchers, the final choice is dictated by two key factors. First, by the specific research question. That is, if the question is one of 'prevalence' (disease burden) then the ideal is a cross-sectional study; if it is a question of 'harm' - a case-control study; prognosis - a cohort and therapy - a RCT. Second, by what resources are available to you. This includes budget, time, feasibility re-patient numbers and research expertise. All these factors will severely limit the choice. While paediatricians would like to see more RCTs, these require a huge amount of resources, and in many situations will be unethical (e.g. potentially harmful intervention) or impractical (e.g. rare diseases). This paper gives a brief overview of the common study types, and for those embarking on such studies you will need far more comprehensive, detailed sources of information.

Leukotriene receptor antagonists in virus-induced wheezing : evidence to date

Virus-induced wheezing is a relatively benign entity that is usually transient in early childhood but is responsible for much health care utilization. The condition, seen traditionally as a subset of those children diagnosed as having frequent episodic asthma, is often treated with inhaled corticosteroids, despite their lack of efficacy. However, there remains some confusion differentiating atopic asthma from virus-induced wheezing in young children and their respective treatment strategies.The demonstration of cysteinyl leukotrienes in the nasopharyngeal secretions of infants and young children who wheeze prompted investigation of the role of leukotriene receptor antagonists in the treatment of virus-induced wheezing for young children with bronchiolitis and virus-induced wheezing.Montelukast, the only leukotriene receptor antagonist studied in young children, has been proven useful in increasing the number of symptom-free days and delaying the recurrence of wheeze in the month following a diagnosis of respiratory syncytial virus-induced wheezing in children aged 3-36 months. Subsequently, in children aged 2-5 years with frequent episodic asthma, primarily involving viral induced attacks in this age group, regular therapy with daily montelukast for 12 months reduced the rate of asthma exacerbations by 31% over placebo, delayed the time to the first exacerbation by 2 months, and lowered the need to prescribe inhaled corticosteroids as preventative therapy. Additionally, montelukast has been demonstrated to be efficacious as an acute episode modifier in children aged 2-14 years (85% children <6 years) with virus-induced wheezing where it was prescribed at the onset of a viral infection in children with an established pattern of viral induced episodes of wheeze in the preceding year. In this study, emergency department visits were reduced by 45%, visits to all health care practitioners were reduced by 23%, and time of preschool/school and parental time off work was reduced by 33% for children who took montelukast for a median of 10 days.At present, there is good evidence to support the use of bronchodilators in the acute treatment of virus- induced wheezing, and increasing evidence to support the use of leukotriene receptor antagonists, in particular montelukast, in the management of children with virus-induced wheezing.

Change in the manifestations of asthma and asthma-related traits in childhood: a latent transition analysis

It is known that asthma is a heterogeneous entity whose manifestations vary with age. Our objective was to examine changes in the manifestation of asthma and asthma-related traits in childhood by defining empirically derived childhood asthma phenotypes and examining their transitions over time.To define the phenotypes we used data on respiratory symptoms, healthcare utilisation, medications, spirometry, airway hyperresponsiveness (AHR), exhaled nitric oxide concentration and atopy from a birth cohort recruited on the basis of having a first-degree relative with asthma. Data were acquired at ages 1.5-11.5 years and analysed using latent transition analysis.In a study population of 370 participants, we classified subjects into four phenotypes: 1) nonatopic, few symptoms (prevalence range from 1.5 to 5 years: 52-60%), 2) atopic, few symptoms (3-21%), 3) nonatopic, asthma and rhinitis symptoms (13-35%), and 4) atopic, asthma and rhinitis symptoms (2-14%) in early childhood; and 1) nonatopic, no respiratory disease (prevalence range from 8 to 11.5 years: 41-46%), 2) atopic, no respiratory disease (23-33%), 3) nonatopic, asthma symptoms, no AHR or airway inflammation (8-12%) and 4) atopic asthma (19%) in mid-childhood. Transitioning between phenotypes was common in early childhood, but less common in later childhood.This analysis represents the first attempt to incorporate longitudinal patterns of several manifestations of asthma into a single model to simultaneously define phenotypes and examine their transitions over time. It provides quantitative support for the view that asthma is a heterogeneous entity, and that some children with wheeze and other respiratory symptoms in early life progress to asthma in mid-childhood, while others become asymptomatic.

Recruiting and retaining general practitioners to a primary care asthma-intervention study in Australia

The need for more evidence-based interventions in primary care is clear. However, it is challenging to recruit general practitioners (GPs) for interventional research. This paper reports on the evaluation of three methods of recruitment that were sequentially used to recruit GPs for a randomised controlled trial of an asthma communication and education intervention in Australia. The recruitment methods (RMs) were: general practices were contacted by project staff from a Department of General Practice, University of Sydney (RM1); general practices were contacted by staff from an independent research organisation (RM2); and general practices were contacted by a medical peer (chief investigator) (RM3). A GP was defined as 'recruited' once they consented and were randomised to a group, and 'retained' if they provided baseline data and did not notify staff of their intention to withdraw at any time during the 12-month study. RM1 was used for the first 6 months, during which 34 (4%) GPs were recruited and 21 (62%) retained from a total of 953 invitations. RM2 was then used for the next 5 months, during which 32 (6%) GPs were recruited and 26 (81%) were retained. Finally over the next 7 months, RM3 recruited 84 (12%) GPs and retained 75 (89%) GPs. In conclusion, use of a medical peer as the first contact was associated with the highest recruitment and retention rate.

Applying established guidelines to team-based learning programs in medical schools: a systematic review

PURPOSE

Team-based learning (TBL), a structured form of small-group learning, has gained popularity in medical education in recent years. A growing number of medical schools have adopted TBL in a variety of combinations and permutations across a diversity of settings, learners, and content areas. The authors conducted this systematic review to establish the extent, design, and practice of TBL programs within medical schools to inform curriculum planners and education designers.

METHOD

The authors searched the MEDLINE, PubMed, Web of Knowledge, and ERIC databases for articles on TBL in undergraduate medical education published between 2002 and 2012. They selected and reviewed articles that included original research on TBL programs and assessed the articles according to the seven core TBL design elements (team formation, readiness assurance, immediate feedback, sequencing of in-class problem solving, the four S's [significant problem, same problem, specific choice, and simultaneous reporting], incentive structure, and peer review) described in established guidelines.

RESULTS

The authors identified 20 articles that satisfied the inclusion criteria. They found significant variability across the articles in terms of the application of the seven core design elements and the depth with which they were described. The majority of the articles, however, reported that TBL provided a positive learning experience for students.

CONCLUSIONS

In the future, faculty should adhere to a standardized TBL framework to better understand the impact and relative merits of each feature of their program.

Improving paediatric asthma outcomes in primary health care: a randomised controlled trial

OBJECTIVE

To evaluate the effectiveness of the Practitioner Asthma Communication and Education (PACE) Australia program, an innovative communication and paediatric asthma management program for general practitioners.

DESIGN

Randomised controlled trial.

SETTING

General practices from two regions in metropolitan Sydney.

PARTICIPANTS

150 GPs, who were recruited between 2006 and 2008, and 221 children with asthma in their care.

INTERVENTION

GPs in the intervention group participated in two 3-hour workshops, focusing on communication and education strategies to facilitate quality asthma care.

MAIN OUTCOME MEASURES

Patient outcomes included receipt of a written asthma action plan (WAAP), appropriate medication use, parent days away from work, and child days away from school or child care. GP outcomes included frequency of providing a WAAP and patient education, communication and teaching behaviour, and adherence to national asthma guidelines regarding medication use.

RESULTS

More patients of GPs in the intervention group reported receipt of a WAAP (difference, 15%; 95% CI, 2% to 28%; adjusted P=0.046). In the intervention group, children with infrequent intermittent asthma symptoms had lower use of inhaled corticosteroids (difference, 24%; 95% CI, -43% to -5%; P=0.03) and long-acting bronchodilators (difference, 19%; 95% CI, -34% to -5%; P=0.02). GPs in the intervention group were more confident when communicating with patients (difference 22%; 95% CI, 3% to 40%; P=0.03). A higher proportion of GPs in the intervention group reported providing a WAAP more than 70% of the time (difference, 23%; 95% CI, 11% to 36%; adjusted P=0.002) and prescribing spacer devices more than 90% of the time (difference, 29%; 95% CI, 16% to 42%; adjusted P=0.02).

CONCLUSIONS

The PACE Australia program improved GPs' asthma management practices and led to improvements in some important patient outcomes.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12607000067471.

A snapshot of general practitioner attitudes, levels of confidence and self-reported paediatric asthma management practice

The prevalence of asthma in Australia is high. Previous findings have suggested that asthma management, particularly in primary care, remains suboptimal and recent government initiatives to improve asthma management and encourage the use of written asthma action plans (WAAPs) in general practice have been implemented. We aimed to assess the attitudes, confidence and self-reported paediatric asthma management practices of a convenience sample of Australian general practitioners (GPs). A baseline questionnaire was administered to GPs as part of a randomised controlled trial. General practitioners (GPs) were recruited from two areas of greater metropolitan Sydney, NSW between 2006 and 2008. Invitations were sent to an estimated 1200 potentially eligible GPs. Of 150 (12.5%) GPs that enrolled, 122 (10.2%) completed the baseline questionnaire. Though 89% were aware of the Australian National Asthma Guidelines, less than 40% were familiar with guideline recommendations. While 85.2% had positive attitudes towards WAAPs, only 45.1% reported providing them frequently. For children with frequent symptoms, 90% agreed they should prescribe daily, inhaled corticosteroids (ICS), and 83% reported currently prescribing ICS to such patients. These findings indicate gaps between GP attitudes and behaviours and highlights opportunities for interventions to improve paediatric asthma management.

Can a management pathway for chronic cough in children improve clinical outcomes: protocol for a multicentre evaluation

Background

Chronic cough is common and is associated with significant economic and human costs. While cough can be a problematic symptom without serious consequences, it could also reflect a serious underlying illness. Evidence shows that the management of chronic cough in children needs to be improved. Our study tests the hypothesis that the management of chronic cough in children with an evidence-based management pathway is feasible and reliable, and improves clinical outcomes.

Methods/Design

We are conducting a multicentre randomised controlled trial based in respiratory clinics in 5 major Australian cities. Children (n = 250) fulfilling inclusion criteria (new patients with chronic cough) are randomised (allocation concealed) to the standardised clinical management pathway (specialist starts clinical pathway within 2 weeks) or usual care (existing care until review by specialist at 6 weeks). Cough diary, cough-specific quality of life (QOL) and generic QOL are collected at baseline and at 6, 10, 14, 26, and 52 weeks. Children are followed-up for 6 months after diagnosis and cough resolution (with at least monthly contact from study nurses). A random sample from each site will be independently examined to determine adherence to the pathway. Primary outcomes are group differences in QOL and proportion of children that are cough free at week 6.

Discussion

The clinical management pathway is based on data from Cochrane Reviews combined with collective clinical experience (250 doctor years). This study will provide additional evidence on the optimal management of chronic cough in children.

Trial registration

ACTRN12607000526471

Optimizing training: what clinicians have to offer and how to deliver it

Since experienced clinicians spend a substantial proportion of their time teaching and supervising trainees, a working knowledge of adult learning is of value. This knowledge will not only make you a more effective teacher, but will be of benefit to you when you are learning new information. There are a number of important issues to keep in mind when teaching your adult trainees. For example, recognize the short attention span of adult learners (10-15 min only!); keep your teaching and learning in context (i.e. clinically relevant); set clear, achievable learning objectives; give regular, constructive feedback to your trainees; and be aware your trainees will have different learning styles and no single teaching method is best for all. Assessment of your trainees needs to cover many different domains, including; knowledge, clinical competence, communication skills (written and verbal), procedural skills, teamwork and professionalism. Clearly, multiple methods of assessment will be essential. Further, a number of observers will be required to improve the validity of these assessment activities.

Perinatal and maternal risk factors for autism spectrum disorders in New South Wales, Australia

BACKGROUND

This study was commenced in 1999 with the aim of examining risk factors for autism using established population-based data for comparison.

METHODS

Cases were ascertained using active surveillance and compared with birth data.

RESULTS

Four risk factors were found to be significantly associated with autism using binary logistic regression analysis; being male [adjusted odds ratio (OR) 4.7, 95% confidence interval (CI) 3.2-7.0], being born prematurely (adjusted OR 2.2, 95% CI 1.5-3.5), having maternal age >/=35 years (adjusted OR 1.7, 95% CI 1.2-2.4) and having a mother born outside Australia (adjusted OR 1.4, 95% CI 1.0-1.9). For analysis completed for pregnancies, rather than live births, multiple birth was also a significant risk factor for one or more children of the pregnancy to be affected by autism (adjusted OR 2.5, 95% CI 1.1-5.5). There was a statistically significant trend towards increasing risk with increasing risk factor 'dose' for gestational age (P = 0.019), multiple birth (P = 0.016) and maternal age (P < 0.001). For mother's country of birth the group with the highest risk were children of mother's born in south-east or north-east Asia. There was a non-significant trend towards a higher proportion of children with developmental disability having risk factors.

CONCLUSION

Replication of risk factors from previous studies and a significant risk factor 'dose' effect add to growing evidence that maternal and perinatal factors are low magnitude risk factors for autism. The association between developmental disability and autism risk factors warrants further examination.

Asthma management and outcomes in Australia: a nation-wide telephone interview survey

BACKGROUND AND OBJECTIVE

Asthma is a high-burden disease for which effective treatment is available. In Australia, there has been a public health campaign directed at increasing the implementation of effective management with the aim of improving asthma outcomes. The aim of this study was to assess the burden of asthma and describe current asthma management in Australia.

METHODS

A computer-assisted telephone interview survey was conducted in 2003/04 among randomly selected participants. Current asthma was defined as self-reported asthma, confirmed by doctor, which was still present and/or associated with symptoms in the last 12 months.

RESULTS

From 46,855 eligible telephone numbers dialled there were 14,271 (30.5%) responses to the screening questionnaire. Among 1734 respondents with current asthma, 1205 (69.5%) completed the detailed questionnaire. Among these, 24.2% of adults and 14.3% children had symptoms during the day or night on most days; 11.3% of adults and 6.0% of children avoided exercise because of asthma symptoms during exercise and 19.4% of adults and 29.7% of children had sought urgent medical care because of an exacerbation of asthma during the preceding year. Among adults with asthma, only 35.6% with daily symptoms and 41.4% with symptoms on most days were taking inhaled steroids. Only 31.1% of adults with daily symptoms had a written asthma action plan.

CONCLUSION

Compared with similar international studies, this study revealed a lower prevalence of frequent asthma symptoms and a higher prevalence of use of inhaled steroids among people with asthma. However, there remains ample scope for improvement in management of patients with frequent symptoms.

Prevention of asthma during the first 5 years of life: a randomized controlled trial

BACKGROUND

Early life exposures may be important in the development of asthma and allergic disease.

OBJECTIVE

To test house dust mite (HDM) avoidance and dietary fatty acid modification, implemented throughout the first 5 years of life, as interventions to prevent asthma and allergic disease.

METHODS

We recruited newborns with a family history of asthma antenatally and randomized them, separately, to HDM avoidance or control and to dietary modification or control. At age 5 years, they were assessed for asthma and eczema and had skin prick tests for atopy.

RESULTS

Of 616 children randomized, 516 (84%) were evaluated at age 5 years. The HDM avoidance intervention resulted in a 61% reduction in HDM allergen concentrations (microg/g dust) in the child's bed but no difference in the prevalence of asthma, wheeze, or atopy (P > .1). The prevalence of eczema was higher in the active HDM avoidance group (26% vs 19%; P = .06). The ratio of omega-6 to omega-3 fatty acids in plasma was lower in the active diet group (5.8 vs 7.4; P < .0001). However, the prevalence of asthma, wheezing, eczema, or atopy did not differ between the diet groups (P > .1).

CONCLUSION

Further research is required to establish whether other interventions can be recommended for the prevention of asthma and allergic disease.

CLINICAL IMPLICATIONS

House dust mite avoidance measures and dietary fatty acid modification, as implemented in this trial during infancy and early childhood, did not prevent the onset of asthma, eczema, or atopy in high-risk children.

Cough in children: definitions and clinical evaluation

The aetiology and management approach for cough in children differs greatly to that in adults, so the empirical approach commonly used in adults is unsuitable for children. Clinical evaluation of cough in children should include an assessment of environmental factors, particularly tobacco smoke, parental concerns and expectations. Most children with acute cough are likely to have an uncomplicated viral acute respiratory tract infection, but the possibility of a more serious problem, especially aspiration of foreign material, should always be considered. Isolated chronic cough in children is rarely asthma, and the term "cough variant asthma" should not be used. Over-the-counter and prescription medications are ineffective for the symptomatic relief of acute cough. Treatment for chronic cough should be based on aetiology. Because of the favourable natural history of cough, a "positive" response in medication trials should not be assumed to be due to the medication. Children should be reassessed within the expected timeframe of response to therapy.

Incidence of autism spectrum disorders in children in two Australian states

AIM

To ascertain the incidence of autism spectrum disorders in Australian children.

SETTING

New South Wales (NSW) and Western Australia (WA), July 1999 to December 2000.

DESIGN

Data were obtained for WA from a prospective register and for NSW by active surveillance.

MAIN OUTCOME MEASURES

Newly recognised cases of autism spectrum disorders (defined as autistic disorder, Asperger disorder and pervasive developmental disorder not otherwise specified [PDD-NOS]) in children aged 0-14 years; incidence was estimated in 5-year age bands (0-4 years, 5-9 years, 10-14 years).

RESULTS

In WA, 252 children aged 0-14 years were identified with autism spectrum disorder (169 with autistic disorder and 83 with Asperger disorder or PDD-NOS). Comparable figures in NSW were 532, 400 and 132, respectively. Most children were recognised with autistic disorder before school age (median age, 4 years in WA and 3 years in NSW). Incidence of autistic disorder in the 0-4-years age group was 5.5 per 10,000 in WA (95% CI, 4.5-6.7) and 4.3 per 10,000 in NSW (95% CI, 3.8-4.8). Incidence was lower in older age groups. The ratio of all autism spectrum disorders to autistic disorder alone was 1.5:1 in WA and 1.3:1 in NSW, and rose with age (1.8:1 and 2.9:1 in 10-14-year-olds in WA and NSW, respectively).

CONCLUSIONS

These are the first reported incidence rates for autism for a large Australian population and are similar to rates reported from the United Kingdom. Ongoing information gathering in WA and repeat active surveillance in NSW will help to monitor any future changes.

Three-year outcomes of dietary fatty acid modification and house dust mite reduction in the Childhood Asthma Prevention Study

BACKGROUND

Two factors thought to influence the risk of asthma are the promoting effect of sensitization to house dust mites and the preventive effect of increased omega-3 fatty acids. Although house dust mite allergen avoidance has been used as a preventive strategy in several trials, the effect of omega-3 fatty acid supplementation in the primary prevention of asthma and allergic disease is not known.

OBJECTIVE

To measure the effects of dietary supplementation with omega-3 fatty acids and house dust mite allergen avoidance in children with a family history of asthma.

METHODS

A total of 616 children at high risk of asthma were enrolled antenatally in a randomized controlled trial, and 526 children remained in the trial at age 3 years. The outcomes were symptoms of allergic disease and allergen sensitization.

RESULTS

There was a significant 10.0% (95% CI, 3.7-16.4) reduction in the prevalence of cough in atopic children in the active diet group ( P=.003; number needed to treat, 10) but a negligible 1.1% (95% CI, -7.1 to 9.5) reduction cough among nonatopic children. There was a 7.2% (95% CI, 10.11-14.3) reduction in sensitization to house dust mite in the active allergen avoidance group ( P=.05; number needed to treat, 14). No significant differences in wheeze were found with either intervention.

CONCLUSION

These results suggest that our interventions, designed to be used in simple public health campaigns, may have a role in preventing the development of allergic sensitization and airways disease in early childhood. This offers the prospect of reducing allergic disease in later life.

Effect of omega-3 fatty acid concentrations in plasma on symptoms of asthma at 18 months of age

The objective of this study was to assess the relation between observed levels of omega-3 fatty acids in plasma and symptoms of asthma and atopy in children at 18 months of age. A total of 616 women at risk of having a child who would develop asthma because of a family history were recruited from the antenatal clinics of six hospitals in Sydney, Australia. Families were randomized to either active omega-3 supplemented or control group. The active group received a daily tuna fish oil supplement and omega-3-rich margarines and cooking oils and the control group received a placebo supplement with polyunsaturated margarines and cooking oils. When the children were 18 months of age an assessment of symptoms was carried out by a research nurse blinded to treatment group allocation. Atopy was measured by skin prick tests, blood was collected to determine serum immunoglobulin E (IgE), and plasma fatty acid concentrations. A total of 376 children (61.0% of total recruited) completed an assessment at 18 months and had blood taken to determine plasma fatty acid concentrations. Omega-3 fatty acid levels were expressed in quintiles of exposure 'as treated' without reference to treatment group allocation. Wheeze ever, doctor visits for wheeze, bronchodilator use and nocturnal coughing were significantly reduced in children in the higher exposure quintiles. Serum IgE was reduced in the highest quintile but not significantly so. There was no difference in diagnosed asthma or atopy between the exposure quintiles. Although wheeze at this age may not be a good indicator of asthma in later childhood, it is encouraging that some symptoms have been reduced in children with high omega-3 fatty acid concentrations in plasma.

Gender differences in habitual activity in children with cystic fibrosis

AIMS

(1) To compare habitual activity levels in prepubescent and pubescent boys and girls with different degrees of CF lung disease severity and healthy controls. (2) To assess the relation between habitual activity levels and measures of fitness, lung function, nutrition, pancreatic status, and quality of life.

METHODS AND RESULTS

A total of 148 children (75 girls and 73 boys) with CF and matched controls were studied. Regardless of disease severity, there were no differences in habitual activity between prepubescent boys and girls with CF. Pubescent boys with CF were significantly more active than girls with the same degree of disease severity. There were no significant differences in habitual activity between prepubescent children with CF and controls. Pubescent children with mild CF were significantly more active than controls, but those with moderate to severe disease were less active than controls. The best correlates with habitual activity levels were anaerobic power, aerobic capacity, and quality of life. In children with moderate to severe disease, nutrition status correlated significantly with activity levels. The impact of pancreatic status on activity levels and other measures of fitness was most apparent in pubescent girls.

CONCLUSION

Gender differences in habitual activity were evident only after the onset of puberty. The impact of pancreatic insufficiency on measures of fitness and habitual activity was greatest in pubescent females. The reason for this gender difference may be an interplay of genetic, hormonal, and societal factors and is the focus of a longitudinal study.

Tracheomalacia, timing of symptoms, and thymic enlargement: cause or coincidence?

The authors report a case of severe primary tracheomalacia in a 3-month-old boy. The left lobe of the enlarged thymus was resected at operation to facilitate aortopexy. The authors suggest a possible role for the enlarging thymus contributing to the delayed onset of the symptoms of tracheomalacia, despite the presence of the tracheal lesion from birth.

Adrenal crises in children treated with high-dose inhaled corticosteroids for asthma

Three children presented with adrenal crises, manifested by vomiting and hypoglycaemia, after protracted courses of high-dose inhaled corticosteroids for asthma. Significant dose reduction was possible in all three without loss of asthma control, emphasising the importance of back-titration to minimise dose. Parents of children taking high doses of inhaled corticosteroids should be alerted to the clinical features of adrenal insufficiency. If suspected, prompt medical assessment should be arranged, including serum glucose and cortisol measurement.

Validation of shuttle tests in children with cystic fibrosis

Shuttle tests are simple, inexpensive field tests that have been used to estimate the cardiorespiratory status of children. It has yet to be validated in children with CF. The aim of this study was to assess the reproducibility and criterion validity of shuttle tests in children with cystic fibrosis (CF). Ninety-three CF patients aged 6 to 16 years of age with a wide range of disease severity performed the study. The 10-m shuttle test was used for children 7 years of age and younger and those deemed too chronically ill by their physicians to perform the longer test (n = 35.) All other children performed the 20-m shuttle test (n = 58). Reproducibility and criterion validity were assessed for each child over a two week period. Gas analysis was performed throughout testing using a polargraphic gas analyzer. The 10-m shuttle tests were reproducible (mean difference between tests VO(2) 2.41 mL/kg/min, CI 3.46,-0.18) and the difference from treadmill testing was not statistically significant (mean difference VO(2) 5.30 mL/kg/min, CI-7.46, 1.18). The 20-m shuttle tests were reproducible (mean difference between tests VO(2) 2.07 mL/kg/min, CI-3.90,0.60) and the difference from treadmill testing was not statistically significant (mean difference VO(2) 3.50 mL/kg/min, CI-4.90, 1.60). We conclude that when formal exercise testing with treadmill or cycle ergometer cannot be performed, the shuttle tests provide a reproducible and valid alternative.

Eighteen-month outcomes of house dust mite avoidance and dietary fatty acid modification in the Childhood Asthma Prevention Study (CAPS)

BACKGROUND

Observational studies have linked house dust mite (HDM) exposure and dietary fatty acid intake with asthma in childhood. However, definitive evidence of their role in the etiology of asthma requires a randomized controlled trial.

OBJECTIVE

We hypothesized that the incidence of asthma and allergy in high-risk children would be reduced by avoidance of HDM allergens, supplementation with omega-3 fatty acids, or the combination of these strategies. We present the results of an interim analysis reporting outcomes assessed at 18 months.

METHODS

A total of 616 pregnant women were randomized to an HDM avoidance intervention, comprising the use of impermeable mattress covers and an acaricide or control and the use of an oil supplement, margarines, and cooking oils containing high levels of omega-3 fatty acids or control. Atopic status was measured by skin prick testing. Symptoms, diagnoses, and medication histories were elicited by means of parental interviews.

RESULTS

The diet intervention resulted in a 9.8% absolute reduction (95% CI, 1.5-18.1; P =.02) in the prevalence of any wheeze and a 7.8% absolute reduction (95% CI, 0.5-15.1, P =.04) in prevalence of wheeze of >1 week, but it had no effect on serum IgE, atopy, or doctors' diagnosis of asthma. The HDM avoidance intervention did not affect these outcomes but was associated with a lower use of oral steroids.

CONCLUSION

Increasing dietary omega-3 fatty acids might have a beneficial effect on the prevalence of wheeze during the first 18 months of life. Follow-up to age 5 years, when the effect of the interventions on asthma risk will be assessed, is underway.

Is asthma prevention possible with dietary manipulation?

What we know: Primary prevention of asthma should be possible because the recent increase in asthma is due to environmental factors. The major modifiable dietary environmental risk factors for childhood asthma are lack of breastfeeding and low intake of omega-3 fatty acids. Randomised controlled trials (RCTs) have shown that interventions using probiotics, hydrolysed milk formulas, and combined dietary manipulation plus airborne allergen avoidance reduce asthma and/or atopy in newborns. Observational studies have shown a 30%-50% reduction in childhood asthma with exclusive breastfeeding for three months, and similar reductions in children who eat fish regularly (ie, have a high intake of omega-3 fatty acids). What we need to know: Will further RCTs using intervention with probiotics reveal identifiable subgroups of children who respond and children who do not respond? Will supplementation of the diet with omega-3 oil reduce the rate of significant clinical atopic disease, particularly asthma? If so, for how long will supplements need to be given? Will effective primary prevention require multiple intervention strategies? If so, how feasible are these as public health interventions? What are the benefits and harms of allergen-avoidance diets in high-risk women who are breastfeeding? Can protein hydrolysate formulas reduce rates of atopy and/or asthma?

Early predictors of asthma

A number of recent cohort and cross-sectional studies have contributed substantial knowledge to factors that influence the early development of asthma. Here, we summarize the recent evidence for the role of early life events such as prenatal factors, infections, diet and allergen exposure, and discuss the implications for future preventative strategies.

The relationship between genotype and exercise tolerance in children with cystic fibrosis

The relationship between fitness and genotype in children with cystic fibrosis (CF) and at least one copy of the DeltaF508 mutation was examined. Genotype was classified according to the second CF mutation. Fitness was measured by peak aerobic capacity (using a modified Bruce protocol during treadmill exercise) and anaerobic power (using the Wingate test on a cycle ergometer). The class of cystic fibrosis transmembrane regulator proteins (CFTR) mutation was statistically related with aerobic capacity, peak anaerobic power, body mass index, lung function (forced expiratory volume in one second), and disease severity as measured by the Shwachman score. Patients with mutations causing defective CFTR production (Class I) or processing (Class II) had a significantly lower peak aerobic capacity (28.6 +/- 4.2 ml/kg/min and 31.7 +/- 5.4 ml/kg/min, respectively) than those with a mutation conferring defective regulation of CFTR (Class III) (43.9 +/- 6.4 ml/kg/min). The peak anaerobic power in subjects with mutations inducing decreased CFTR conduction (Class IV) or CFTR mRNA (Class V), were significantly higher (11.4 +/- 1.7 and 11.6 +/- 1.5 watts/kg, respectively) than children with Class I (9.7 +/- 1.4 watts/kg), Class II (9.8 +/- 1.4 watts/kg), or Class III (10.5 +/- 1.8 watts/kg) mutations. There were no statistically significant differences in the lung function of patients with the different mutations. These results indicate a relationship between CF genotype and some measures of fitness, the mechanisms of which remain to be determined.

Randomized controlled study of in-hospital exercise training programs in children with cystic fibrosis

The aim of this study was to compare aerobic and resistance training in children with cystic fibrosis (CF) admitted to hospital with an intercurrent pulmonary infection with a control group. The subjects were randomized into three groups on the first day of admission. The fat-free mass (FFM) was calculated, using the skin fold thickness from four sites (biceps, triceps, subscapular, and iliac crest). Pulmonary function tests were performed within 36 hr of admission and repeated on discharge from the hospital, and again at 1 month after discharge. All subjects performed an incremental treadmill exercise test, using a modified Bruce protocol. Lower limb strength was measured using a Cybex dynamometer. An assessment of quality of life was made using the Quality of Well Being Scale, as previously reported. Activity levels were measured using a 7-day activity diary, and subjects also wore an accelerometer on their hips. There were no significant differences between the three groups in terms of disease severity, and length of stay in hospital. Subjects in all three groups received intravenous antibiotics and nutritional supplementation as determined by the physician. Children randomized to the aerobic training group participated in aerobic activities for five sessions, each of 30-min duration, a week. The children randomized to the resistance training group exercised both upper and lower limbs against a graded resistance machine. Subjects in the control group received standard chest physiotherapy. Our study demonstrated that children who received aerobic training had significantly better peak aerobic capacity, activity levels, and quality of life than children who received the resistance training program. Children who received resistance training had better weight gain (total mass, as well as fat-free mass), lung function, and leg strength than children who received aerobic training. A combination of aerobic and resistance training may be the best training program, and future studies to assess optimal training programs for CF patients are indicated.

The role of corticosteroids in the management of childhood asthma

Preventive treatment: * Inhaled corticosteroids are indicated in children with asthma who have more than mild persistent asthma or are unresponsive to non-steroidal medications after 2-4 weeks. * Initial administration of 400 microg/day of chlorofluorocarbon-beclomethasone dipropionate, or budesonide, or 200 microg/day of fluticasone propionate or hydrofluoroalkane-beclomethasone dipropionate, is suggested, with subsequent titration of the dose to achieve ongoing control with the lowest dose possible. * In situations where asthma control cannot be achieved with the above doses of inhaled corticosteroids, the addition of a long-acting beta2-agonist, theophylline or a leukotriene antagonist should be considered. * Specialist referral is recommended in children requiring high doses of inhaled steroids, regular oral steroids or in whom there is concern about possible steroid side effects. Treatment of acute asthma: * Systemic corticosteroid therapy is recommended for children with moderate to severe acute asthma or if there is incomplete response to beta2-agonists. * Initial administration of 1 mg/kg prednisolone (maximum, 50 mg) orally is suggested, and this may be repeated every 12-24 hours, depending on response. While a course of up to three days is generally sufficient, in more severe cases a prolonged course (with tapering) may occasionally be indicated. * The need for recurrent systemic corticosteroid therapy for acute episodes is an indication for reassessment of the child's interval therapy.

The childhood asthma prevention study (CAPS): design and research protocol of a randomized trial for the primary prevention of asthma

The Childhood Asthma Prevention Study is a randomized controlled trial to measure whether the incidence of atopy and asthma can be reduced by house dust mite allergen reduction, a diet supplemented with omega-3 fatty acids, or a combination of both interventions. Six hundred and sixteen pregnant women whose unborn children were at high risk of developing asthma because of a family history were randomized prenatally. Study groups are as follows: Group A (placebo diet intervention, no house dust mite reduction), Group B (placebo diet intervention, active house dust mite reduction), Group C (active diet intervention, no house dust mite reduction), and Group D (active diet intervention, active house dust mite reduction). The house dust mite reduction intervention comprises use of physical and chemical methods to reduce allergen contact. The dietary intervention comprises use of a daily oil supplement from 6 months or at onset of bottle-feeding, and use of margarine and cooking oils based on sunflower or canola oils to increase omega-3 dietary intake. Data is collected quarterly until the infant is 1 year old and then half yearly until age 5 years. Questionnaires are used to collect respiratory illness history and information about diet and home environment. Dust is collected from the child's bed and bedroom and playroom floors. Blinded assessments are conducted at 18 months, 3 years, and 5 years. Skin prick tests to common allergens, blood tests, and detailed illness, medication use, and vaccination histories are collected. Primary outcomes will be the development of allergic sensitization and the presence and severity of asthma. This study is designed to measure the effectiveness of allergen reduction and dietary supplementation, both separately and in combination, for the primary prevention of atopy and asthma. The results of this study may have important implications for public health policies to reduce the incidence of childhood asthma. Control Clin Trials 2001;22:333-354

Continuing the debate about measuring asthma in population studies

The reasons for measuring atopy and airway hyperresponsiveness (AHR) and the methods of validating measurements of asthma in population studies continue to be debated. The debate has centred around standards against which to validate asthma measurements but the absence of a "gold standard" makes the criterion validation of measurements difficult. Questionnaires will always be useful but cannot be validated against a doctor diagnosis because of self-selection and recall biases. In practice, measurements should be selected on the merits of what they measure rather than being regarded as validated or non-validated alternatives. The measurement of AHR is invaluable because it is reliable, not influenced by variations in symptom perception or diagnostic trends, and is closely related to the underlying mechanisms of asthma. The value of AHR lies in its high specificity (rate of true negatives) and low sensitivity (rate of false positives) against asthma symptoms which gives additional information about symptomatic subjects. Atopy is also a useful test and, in quantifying its association with asthma, we should not place any currency on ecological evidence. Atopy is a strong risk factor for asthma in the presence of regionally specific allergens and ecological analyses that ignore these effects are diversionary rather than productive. For preventing asthma, we need to identify the group at greatest risk of developing it, measure the risk factors with precision, and develop interventions that are effective in changing environmental exposures and homogeneous outcomes. This is the only approach that has the potential to lead to significant public health benefits.

Problems and possibilities in understanding the natural history of asthma

In early life, asthma symptoms can occur intermittently or may not be severe enough to limit normal activities, which makes it difficult for the clinician to make reliable predictions and administer therapy with some precision. In the case of pediatric asthma, the identification of children who will experience the development of a clinically important illness that will impair their quality of life can be a complex process. The usual methods for describing this information include the prognostic statistics of sensitivity, specificity, likelihood ratio, and positive predictive value. The sensitivity, specificity, and likelihood ratio of various early markers of asthma have been calculated from several cohort studies. (J Allergy Clin Immunol 2000;106:S144-52.)

Epidemiology of invasive pneumococcal disease in urban New South Wales, 1997-1999

OBJECTIVES

To describe the serotypes, incidence and morbidity of invasive pneumococcal disease in urban New South Wales.

DESIGN

Prospective laboratory surveillance.

SETTING

Microbiology laboratories and hospitals in the Sydney, Hunter and Illawarra Statistical Divisions of NSW, June 1997 to May 1999.

RESULTS

1270 cases were identified in two years. Incidence of disease was highest in those aged < 2 years (96.4 per 100,000; 95% CI, 83.7-107.9) and > or = 85 years (100.1 per 100,000; 95% CI, 81.8-121.3). Incidence of disease increased significantly from the age of 60 years, compared with low rates in those aged 5-59 years. Underlying diseases predisposing to pneumococcal infection increased with age, from 4% (< 2 years) to 60% (> or = 65 years). A seven-valent conjugate vaccine would have covered 84.8% of serotypes in those aged 0-14 years, falling to 69% in those > or = 15 years. Penicillin resistance was significantly higher in the < 5 years group (19.0%) than in older people (14.6%).

CONCLUSIONS

Incidence of invasive pneumococcal disease was higher in this study using active surveillance than in previous Australian studies. An effective sevenvalent conjugate pneumococcal vaccine could prevent more than 80% of cases in children aged < 5 years.

Problems and possibilities in understanding the natural history of asthma

In early life, asthma symptoms can occur intermittently or may not be severe enough to limit normal activities, which makes it difficult for the clinician to make reliable predictions and administer therapy with some precision. In the case of pediatric asthma, the identification of children who will experience the development of a clinically important illness that will impair their quality of life can be a complex process. The usual methods for describing this information include the prognostic statistics of sensitivity, specificity, likelihood ratio, and positive predictive value. The sensitivity, specificity, and likelihood ratio of various early markers of asthma have been calculated from several cohort studies.

Outcome evaluation of early discharge of asthmatic children from hospital: a randomized control trial

The objective of our study was to compare the safety and efficacy of discharging asthmatic children from hospital on three versus four hourly nebulized salbutamol. The setting was a tertiary referral paediatric hospital in Sydney, NSW, Australia. The design was a randomized controlled parallel group study. All children admitted to hospital with acute asthma and who were over 18 months of age were eligible to enter the study. Patients were excluded if they had non-English speaking parents, no telephone, or chronic cardiac or neurological disease. Children were treated according to standard asthma management but were randomly allocated to be discharged on three or four hourly nebulized salbutamol. Patients were surveyed using a telephone questionnaire 1 to 2 weeks after discharge. The primary outcome measure was re-presentation to the Emergency Department (ED) within 7 days. Other outcomes included readmission to hospital, re-presentation to the local doctor, parental satisfaction and length of hospital stay. A total of 63 children were enrolled in the study (32 in the three hourly group and 31 in the four hourly group). There were no re-presentations to the ED or hospital readmissions within 1 to 2 weeks in either group. However, re-presentations to the local doctor were common, 71.8% in the three hourly and 74.1% in the four hourly groups, respectively. These were predominantly for routine review. The mean (+/- SD) hospital length of stay was not significantly different between the three and four hourly groups, 48.94 (+/- 20.61) and 54.88 (+/- 32.59) hours, respectively (P = 0.672). Parents felt the timing of discharge was 'too early' in five (15.6%) of three hourly and five (16.1%) of four hourly patients. Three (9.7%) of the four hourly but none of the three hourly patients felt they were sent home 'later than necessary'. Five (15.1%) of the three hourly and three (9.7%) of the four hourly group parents did not feel comfortable looking after their child at home immediately after discharge. None of these differences were statistically significant. Discharge of asthmatic children from hospital on three hourly nebulized salbutamol is as safe and effective as on four hourly. Parents are generally very satisfied with timing of discharge, irrespective of frequency of nebulization. Earlier discharge benefits both the child and their family, and improves hospital bed utilization.

Is asthma documentation improved by computer-facilitated data entry?

The documentation of acute asthma in written medical records was compared with data entered into a Computer-Assisted Triage System (CATS) in 104 children who presented to the emergency department and subsequently admitted to the Royal Alexandra Hospital for Children, Sydney. A total of 65 items in 5 categories were analysed and satisfactory documentation was defined as the recording of a specific item in more than 80% of records (written or electronic). Satisfactory documentation was observed for all 6 items in visit details and 9 out of 10 items in triage details for both recording systems. Nursing observations were better documented in the medical record than in CATS (87 vs 25%; kappa = 0.63). Documentation of medical details was also worse in CATS (75 vs 25%; kappa = 0.24) and the documentation of asthma severity was poor in both systems (31 vs 0%; kappa = 0.31). Attempts to improve asthma documentation through the development of a computerized medical record have highlighted further barriers to documentation.

A review of open biopsy for mediastinal masses

OBJECTIVE

To review the recent experience with biopsied mediastinal lesions in children and to assess the impact of recent advances in imaging and surgical techniques on diagnosis.

METHODOLOGY

The clinical and radiological features of 55 patients who had mediastinal biopsies at The Royal Alexandra Hospital For Children (RAHC) over 15 years were reviewed.

RESULTS

Fifty-five patients presented to RAHC between 1978 and 1993 with lesions of the mediastinum requiring biopsy of that site. Thirty-one of the 55 (56%) lesions were malignant. Neurogenic tumours were the most common (40%). In order of frequency the following lesions were found: neuroblastoma (15), teratoma (eight), non-Hodgkin's lymphoma (NHL; eight), enteric cyst/duplication (five), ganglioneuroma (five), bronchogenic cyst (three), ganglioneuroblastoma (two), lymphangioma (two), abscess (two), Hodgkin's lymphoma (HL; two), oesophageal granuloma (one), Langerhan's cell histiocytosis (one), congenital fibromatosis (one). Eighty-two per cent of neurogenic tumours were located in the posterior mediastinum, while 75% of teratomas and 100% lymphoid tumours were located anteriorly. Symptoms were generally unhelpful in establishing a specific diagnosis and in 27% of cases the lesions were discovered incidentally. Physical signs, such as thoracic inlet obstruction and neurological findings, were helpful clinically in localizing lesions within the mediastinum. Chest radiography enabled lesions to be subdivided within the mediastinum. This localization, in combination with the age at presentation, predicted the tissue diagnosis. Computerized tomography (CT) and magnetic resonance imaging (MRI) further defined the lesion and demonstrated involvement of adjacent structures. Histology, however, was essential to distinguish benign from malignant lesions.

CONCLUSIONS

The clinical presentation of mediastinal masses is often non-specific or incidental. Despite recent advances in imaging technology and biopsy techniques, full histological examination is required to exclude malignancy.