Childhood fish oil supplementation modifies associations between traffic related air pollution and allergic sensitisation

BACKGROUND

Studies of potential adverse effects of traffic related air pollution (TRAP) on allergic disease have had mixed findings. Nutritional studies to examine whether fish oil supplementation may protect against development of allergic disease through their anti-inflammatory actions have also had mixed findings. Extremely few studies to date have considered whether air pollution and dietary factors such as fish oil intake may interact, which was the rationale for this study.

METHODS

We conducted a secondary analysis of the Childhood Asthma Prevention Study (CAPS) birth cohort, where children were randomised to fish oil supplementation or placebo from early life to age 5 years. We examined interactions between supplementation and TRAP (using weighted road density at place of residence as our measure of traffic related air pollution exposure) with allergic disease and lung function outcomes at age 5 and 8 years.

RESULTS

Outcome information was available on approximately 400 children (~ 70% of the original birth cohort). Statistically significant interactions between fish oil supplementation and TRAP were seen for house dust mite (HDM), inhalant and all-allergen skin prick tests (SPTs) and for HDM-specific interleukin-5 response at age 5. Adjusting for relevant confounders, relative risks (RRs) for positive HDM SPT were RR 1.74 (95% CI 1.22-2.48) per 100 m local road or 33.3 m of motorway within 50 m of the home for those randomised to the control group and 1.03 (0.76-1.41) for those randomised to receive the fish oil supplement. The risk differential was highest in an analysis restricted to those who did not change address between ages 5 and 8 years. In this sub-group, supplementation also protected against the effect of traffic exposure on pre-bronchodilator FEV₁/FVC ratio.

CONCLUSIONS

Results suggest that fish oil supplementation may protect against pro-allergic sensitisation effects of TRAP exposure. Strengths of this analysis are that supplementation was randomised and independent of TRAP exposure, however, findings need to be confirmed in a larger experimental study with the interaction investigated as a primary hypothesis, potentially also exploring epigenetic mechanisms. More generally, studies of adverse health effects of air pollution may benefit from considering potential effect modification by diet and other factors.

TRIAL REGISTRATION

Australia New Zealand Clinical Trial Registry. www.anzctr.org.au Registration: ACTRN12605000042640 , Date: 26th July 2005. Retrospectively registered, trial commenced prior to registry availability.

Improved spirometric detection of small airway narrowing: concavity in the expiratory flow-volume curve in people aged over 40 years

BACKGROUND AND OBJECTIVE

We have explored whether assessing the degree of concavity in the descending limb of the maximum expiratory flow-volume curve enhanced spirometric detection of early small airway disease.

METHODS

We used spirometry records from 890 individuals aged ≥40 years (mean 59 years), recruited for the Burden of Obstructive Lung Disease Australia study. Central and peripheral concavity indices were developed from forced expired flows at 50% and 75% of the forced vital capacity, respectively, using an ideal line joining peak flow to zero flow.

RESULTS

From the 268 subjects classified as normal never smokers, mean values for post-bronchodilator central concavity were 18.6% in males and 9.1% in females and those for peripheral concavity were 50.5% in males and 52.4% in females. There were moderately strong correlations between concavity and forced expired ratio (forced expiratory volume in 1 second/forced vital capacity) and mid-flow rate (forced expiratory flow between 25% and 75% of the FVC [FEF25%-75%]; r=-0.70 to -0.79). The additional number of individuals detected as abnormal using the concavity indices was substantial, especially compared with FEF25%-75%, where it was approximately doubled. Concavity was more specific for symptoms.

CONCLUSION

The inclusion of these concavity measures in the routine reports of spirometry would add information on small airway obstruction at no extra cost, time, or effort.

Atopy in people aged 40 years and over: Relation to airflow limitation

BACKGROUND

Previous studies have reached conflicting conclusions about the role of atopy as a risk factor for COPD. In part, this is attributable to variation in the definitions of airflow limitation and the treatment of people with asthma.

OBJECTIVE

To establish whether there is any independent association between atopy and post-bronchodilator airflow limitation in the general population aged 40 years and over.

METHODS

A cross-sectional survey was conducted in a general population sample of 2415 people aged 40 years and over in Australia. A history of ever being diagnosed with asthma was elicited by questionnaire. Atopy was defined as any skin prick test weal to common aeroallergens ≥4 mm. Airflow limitation was defined as post-bronchodilator spirometric (FEV₁ /FVC) ratio <lower limit of normal. Analyses were adjusted for potential confounding due to age, sex, smoking, race and socio-economic status.

RESULTS

The prevalence of atopy, ever diagnosed asthma and post-bronchodilator airflow obstruction was 44.8%, 19.3% and 7.5%, respectively. In the population as a whole, atopy was associated with lower FEV₁ (adjusted difference -0.068L, 95% confidence interval (CI) -0.104 to -0.032), FVC (adj. difference -0.043L, 95% CI -0.086 to -0.0009) and post-bronchodilator FEV₁/FVC ratio (adj. difference -0.011, 95% CI -0.017 to -0.0055). The effect of atopy on lung function was no longer apparent when participants who reported ever diagnosed asthma were excluded (FEV₁ -0.011L, [95% CI -0.05 to 0.028L], FVC -0.012L [95% CI -0.060 to 0.036] and FEV₁/FVC ratio -0.0012 [95% CI -0.0072 to 0.0047L]).

CONCLUSION AND CLINICAL RELEVANCE

The apparent association between atopy and post-bronchodilator airflow limitation in the general population appears to be explained by the association between atopy and having ever diagnosed asthma and the effect of asthma on lung function.

Impact of childhood asthma on growth trajectories in early adolescence: Findings from the Childhood Asthma Prevention Study (CAPS)

BACKGROUND AND OBJECTIVE

Understanding the associations between childhood asthma and growth in early adolescence by accounting for the heterogeneity of growth during puberty has been largely unexplored. The objective was to identify sex-specific classes of growth trajectories during early adolescence, using a method which takes the heterogeneity of growth into account and to evaluate the association between childhood asthma and different classes of growth trajectories in adolescence.

METHODS

Our longitudinal study included participants with a family history of asthma born during 1997-1999 in Sydney, Australia. Hence, all participants were at high risk for asthma. Asthma status was ascertained at 8 years of age using data from questionnaires and lung function tests. Growth trajectories between 11 and 14 years of age were classified using a latent basis growth mixture model. Multinomial regression analyses were used to evaluate the association between asthma and the categorized classes of growth trajectories.

RESULTS

In total, 316 participants (51.6% boys), representing 51.3% of the entire cohort, were included. Sex-specific classes of growth trajectories were defined. Among boys, asthma was not associated with the classes of growth trajectories. Girls with asthma were more likely than girls without asthma to belong to a class with later growth (OR: 3.79, 95% CI: 1.33, 10.84). Excluding participants using inhaled corticosteroids or adjusting for confounders did not significantly change the results for either sex.

CONCLUSION

We identified sex-specific heterogeneous classes of growth using growth mixture modelling. Associations between childhood asthma and different classes of growth trajectories were found for girls only.

Telomere length in early childhood: Early life risk factors and association with carotid intima-media thickness in later childhood

BACKGROUND

Reduced telomere length is a measure of biological aging that is predictive of cardiac events in adults, and has been mechanistically implicated in the onset and progression of atherosclerosis. We sought to describe the early life factors associated with leukocyte telomere length in early childhood, and to determine whether telomere length measured during early childhood is associated with arterial wall thickening later in childhood.

DESIGN

A longitudinal birth cohort recruited antenatally in Sydney from 1997 to 1999.

METHODS

Leukocyte telomere length was measured in 331 children at age 3.6 years (SD 1.0); of whom 268 children without diabetes had carotid intima-media thickness assessed by ultrasound at age 8 years.

RESULTS

Male sex, younger paternal age and higher maternal body mass index were associated with shorter telomere length in early childhood, which in turn was associated with greater carotid intima-media thickness at age 8 years (standardised β = -0.159, P = 0.01). There was a graded association across quartiles of telomere length (Ptrend = 0.001) with the highest odds of elevated intima-media thickness (>75th percentile) being in children with the shortest telomeres (odds ratio 4.00 (95% confidence interval 1.58 to 10.14) relative to those with the longest telomeres, P = 0.003). This association remained after adjustment for early life risk factors (Ptrend = 0.001).

CONCLUSIONS

Reduced telomere length in early childhood is independently associated with arterial wall thickness in later childhood, suggesting that reduced telomere length during early childhood may be a marker of vascular disease risk.

Absence of back to school peaks in human rhinovirus detections and respiratory symptoms in a cohort of children with asthma

Much of what is known about the seasonality of human rhinovirus (hRV) infections has been learned from the study of acute asthma exacerbations presenting to emergency care, including those among children at the start of the school term. Much less is known about the patterns of hRVs in the community. In this study, viruses and day-to-day symptoms of asthma and colds were monitored twice weekly in 67 children with asthma aged 5-12 years, over a 15 month period in Sydney, Australia. Overall hRV was detected in 314/1232 (25.5%) of nasal wash samples and 142/1231 (11.5%) of exhaled breath samples; of these, 231 and 24 respectively were genotyped. HRVs were detected with similar prevalence rate throughout the year, including no peak in hRV prevalence following return to school. No peaks were seen in asthma and cold symptoms using twice-weekly diary records. However, over the same period in the community, there were peaks in asthma emergency visits both at a large local hospital and in state-wide hospitalizations, following both return to school (February) and in late autumn (May) in children of the same age. This study suggests that hRV infections are common throughout the year among children, and differences in virus prevalence alone may not account for peaks in asthma symptoms.

Rhinoviruses significantly affect day-to-day respiratory symptoms of children with asthma

BACKGROUND

Viruses are frequently associated with acute exacerbations of asthma, but the extent to which they contribute to the level of day-to-day symptom control is less clear.

OBJECTIVE

We sought to explore the relationship between viral infections, host and environmental factors, and respiratory symptoms in children.

METHODS

Sixty-seven asthmatic children collected samples twice weekly for an average of 10 weeks. These included nasal wash fluid and exhaled breath for PCR-based detection of viral RNA, lung function measurements, and records of medication use and asthma and respiratory symptoms in the previous 3 days. Atopy, mite allergen exposure, and vitamin D levels were also measured. Mixed-model regression analyses were performed.

RESULTS

Human rhinoviruses (hRVs) were detected in 25.5% of 1232 nasal samples and 11.5% of breath samples. Non-hRV viruses were detected in less than 3% of samples. hRV in nasal samples was associated with asthma symptoms (cough and phlegm: odds ratio = 2.0; 95% CI = 1.4-2.86, P = .0001; wheeze and chest tightness: odds ratio = 2.34, 95% CI = 1.55-3.52, P < .0001) and with cold symptoms, as reported concurrently with sampling and 3 to 4 days later. No differences were found between the 3 hRV genotypes (hRV-A, hRV-B, and hRV-C) in symptom risk. A history of inhaled corticosteroid use, but not atopic status, mite allergen exposure, or vitamin D levels, modified the association between viruses and asthma symptoms.

CONCLUSION

The detection of nasal hRV was associated with a significantly increased risk of day-to-day asthma symptoms in children. Host, virus genotype, and environmental factors each had only a small or no effect on the relationship of viral infections to asthma symptoms.

Weighted road density and allergic disease in children at high risk of developing asthma

Background

Evidence for an association between traffic-related air pollution and allergic disease is inconsistent, possibly because the adverse effects may be limited to susceptible subgroups and these have not been identified. This study examined children in the Childhood Asthma Prevention Study (CAPS), potentially susceptible to air pollution effects because of a family history of asthma.

Methods

We examined cross-sectional associations at age eight years between road density within 75 m and 50 m of home address weighted by road type (traffic density), as a proxy for traffic-related air pollution, on the following allergic and respiratory outcomes: skin prick tests (SPTs), total and specific serum IgE, pre- and post-bronchodilator lung function, airway hyperresponsiveness, exhaled NO, and reported asthma and rhinitis.

Results

Weighted road density was positively associated with allergic sensitisation and allergic rhinitis. Adjusted relative risk (RR) for house dust mite (HDM) positive SPT was 1.25 (95% CI: 1.06–1.48), for detectable house dust mite-specific IgE was 1.19 (95% CI: 1.01–1.41) and for allergic rhinitis was 1.30 (95% CI: 1.03–1.63) per 100 m local road or 33.3 m motorway within 50 m of home. Associations were also seen with small decrements of peak and mid-expiratory flows and increased risk of asthma, current wheeze and rhinitis in atopic children.

Conclusion

Associations between road density and allergic disease were found in a potentially susceptible subgroup of children at high risk of developing atopy and asthma.

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.

Weight gain in infancy and vascular risk factors in later childhood

OBJECTIVE

We hypothesized that early weight gain would be associated with incident obesity, higher blood pressure, systemic inflammation, and arterial wall thickening in later childhood.

METHODS

A longitudinal birth cohort was recruited antenatally from 2 maternity hospitals in Sydney, Australia, between September 1997 and December 1999. Three hundred ninety-five nondiabetic children who were followed to age 8 years had complete data for early weight gain and arterial wall thickness.

RESULTS

Independent predictors of excess early weight gain (age 0-18 months; adjusted for height gain) included male gender (0.411 kg [SE: 0.103], P < .001), fewer weeks' gestation (-0.121 kg [SE: 0.044] per week, P = .006), birth length (0.156 kg [SE: 0.024] per cm, P < .001), and failure to breastfeed to 6 months of age (0.498 kg [SE: 0.108], P < .001). Early height-adjusted weight gain was significantly associated with later childhood overweight (odds ratio [OR]: 1.67 [95% confidence interval (CI): 1.26 to 2.20] per kg) and obesity (OR: 2.07 [95% CI: 1.53 to 2.79] per kg), excess central adiposity (OR: 1.54 [95% CI: 1.20 to 1.98] per kg), higher systolic blood pressure (1.24 mm Hg [SE: 0.33] per kg, P < .001), higher C-reactive protein (0.17 mg/dL [SE: 0.06] per 100% increase in weight gain, P = .006), and greater carotid intima-media thickness (0.012 mm [SE: 0.004] per kg, P = .002).

CONCLUSIONS

Early postnatal weight gain from birth to age 18 months is significantly associated with later childhood overweight and obesity, excess central adiposity, and greater arterial wall thickness.

Respiratory symptoms and illness in older Australians: the Burden of Obstructive Lung Disease (BOLD) study

OBJECTIVE

To measure the prevalence of chronic obstructive pulmonary disease (COPD) among people aged 40 years or older in Australia.

DESIGN, SETTING AND PARTICIPANTS

A cross-sectional study of people in the community aged ≥ 40 years, selected at random using electoral rolls, in six sites chosen to reflect the sociodemographic and geographic diversity of Australia, conducted between 2006 and 2010. Standardised questionnaires were administered by interview. Forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and the FEV1/FVC ratio were measured by spirometry, before and after bronchodilator administration.

MAIN OUTCOME MEASURE

Prevalence of COPD, classified according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2006 criteria.

RESULTS

Complete data were available for 1620 men (participation rate, 26%) and 1737 women (participation rate, 28%). The prevalence of GOLD Stage II or higher COPD (defined as post-bronchodilator FEV₁/FVC ratio < 0.70 and FEV₁ < 80% predicted) was 7.5% (95% CI, 5.7%-9.4%) among people aged ≥ 40 years, and 29.2% (95% CI, 18.1%-40.2%) among those aged ≥ 75 years. Among people aged ≥ 40 years, the prevalence of wheeze in the past 12 months was 30.0% (95% CI, 27.5%-32.5%), and prevalence of shortness of breath when hurrying on the level or climbing a slight hill was 25.2% (95% CI, 22.7%-27.6%).

CONCLUSIONS

Symptoms and spirometric evidence of COPD are common among people aged 40 years or older and increase with age. Further research is needed to better understand the diagnosis and management of COPD in Australia, along with continuing efforts to prevent the disease.

Respiratory health before and after the opening of a road traffic tunnel: a planned evaluation

Objective

The construction of a new road tunnel in Sydney, Australia, and concomitant reduction in traffic on a major road presented the opportunity to study the effects of this traffic intervention on respiratory health.

Methods

We made measurements in a cohort of residents in the year before the tunnel opened (2006) and in each of two years afterwards (2007–2008). Cohort members resided in one of four exposure zones, including a control zone. Each year, a respiratory questionnaire was administered (n = 2,978) and a panel sub-cohort (n = 380) performed spirometry once and recorded peak expiratory flow and symptoms twice daily for nine weeks.

Results

There was no consistent evidence of improvement in respiratory health in residents living along the bypassed main road, despite a reduction in traffic from 90,000 to 45,000 vpd. Residents living near tunnel feeder roads reported more upper respiratory symptoms in the survey but not in the panel sub-cohort. Residents living around the tunnel ventilation stack reported more upper and lower respiratory symptoms and had lower spirometric volumes after the tunnel opened. Air pollutant levels measured near the stack did not increase over the study period.

Conclusion

The finding of adverse health effects among residents living around the stack is unexpected and difficult to explain, but might be due to unmeasured pollutants or risk factors or an unrecognized pollutant source nearby. The lack of improvement in respiratory health among people living along the bypassed main road probably reflects a minimal change in exposure due to distance of residence from the road.

Carotid extra-medial thickness in childhood: early life effects on the arterial adventitia

OBJECTIVE

Structural modification of the arterial adventitia may be an early event in atherosclerosis. Carotid extra-medial thickness is a new measure of arterial adventitial thickness. We examined the association of cardiovascular risk factors with extra-medial thickness, in childhood.

METHODS

Carotid extra-medial thickness was assessed by high-resolution ultrasound in 389 non-diabetic children aged 8-years. A non-fasting blood sample was collected from 314 participants. Associations of gender, age, lipoproteins, blood pressure, BMI z-score, waist:height ratio and parental history of early vascular disease, with extra-medial thickness were examined.

RESULTS

Carotid extra-medial thickness was lower in girls (r=-.163, P=.001) and directly associated with systolic (r=.128, P=.009), diastolic blood pressure (r=.130, P=.009), and height (r=.170, P=.0006). These associations remained after adjustment for carotid intima-media thickness. In multivariable analysis including carotid intima-media thickness, only gender and height were significantly associated with carotid extra-medial thickness. In gender-stratified analysis, the strongest associations with extra-medial thickness were BMI z-score (r=.181, P=.01), height (r=.210, P=.003) and diastolic blood pressure (r=.167, P=.02) for boys; and systolic blood pressure (r=.153, P=.03) and parental history of premature cardiovascular disease (r=.139, P=.05) for girls. The association of BMI z-score with extra-medial thickness differed by gender (P-interaction=.04).

CONCLUSIONS

Carotid extra-medial thickness is independently associated with gender and height in childhood. Extra-medial thickness may provide important information concerning early arterial health, particularly related to the arterial adventitia.

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.

Systematic review and meta-analysis investigating breast feeding and childhood wheezing illness

There is conflicting evidence concerning the relationship between breast feeding and wheezing illness. The objective of this study was to investigate whether there is any association between breast feeding and wheezing in children aged over 5 years and to discover possible sources of heterogeneity. An electronic search of MEDLINE and EMBASE databases was conducted from January 2000 to June 2010. In addition, reference lists from relevant publications were searched. Birth cohort, cross-sectional and case-control studies were included if they measured any breast feeding or exclusive breast feeding for 3 or 4 months. Wheezing illness, including asthma, was identified based on symptoms, reported diagnosis or objective criteria. Thirty-one publications were identified for meta-analysis. There was no association found between any or exclusive breast feeding and wheezing illness, although there was a high level of heterogeneity between the studies. Subgroup analysis revealed that any breast feeding slightly lowers the odds of wheeze (pooled odds ratio 0.92 [0.86, 0.98]) but slightly increases the odds of asthma defined by specific criteria (pooled odds ratio 1.10 [1.00, 1.22]). This meta-analysis does not provide evidence that breast feeding is protective against wheezing illness in children aged 5 years and over. The difference in the effects of breast feeding according to the nature of the wheezing illness highlights the importance of the heterogeneity of illness phenotypes.

Snoring is not associated with adverse effects on blood pressure, arterial structure or function in 8-year-old children: the Childhood Asthma Prevention Study (CAPS)

AIMS

To study the association between childhood snoring and cardiovascular risk factors.

METHODS

Cross-sectional analyses of a population-based birth cohort, who had been participants in a randomised controlled trial of interventions to prevent asthma and who were assessed at age 8 years. The presence and frequency of snoring were assessed by parent-completed questionnaire. We measured a wide range of cardiovascular function markers including non-fasting serum lipoproteins, blood pressure, high-sensitivity C-reactive protein, carotid artery intima media thickness (by ultrasound), brachial pulse wave velocity and augmentation index (by applanation tonometry).

RESULTS

Of 409 children whose snoring status was assessed at age 8 years, 321 had lipid and 386 had arterial structure and function measurements. Snoring was not independently associated with blood pressure, carotid artery intima media thickness or measures of arterial stiffness (all P > 0.05). Increasing snoring frequency was independently associated with lower high-density lipoprotein cholesterol (-0.032 g/dL per step, 95% confidence interval -0.060 to -0.003), although the difference in high-density lipoprotein between snorers and non-snorers was not significant (P = 0.052). An association of snoring frequency with brachial pulse wave velocity differed according to body mass index (P = 0.03) and was the reverse of that expected.

CONCLUSIONS

Parentally reported snoring was not independently associated with adverse measurements of metabolic markers, vascular structure or function in 8-year-old children. Parental reports of snoring may be below the treatment threshold without additional diagnosis via sleep studies.

Feasibility study of a communication and education asthma intervention for general practitioners in Australia

The Physician Asthma Care Education (PACE) program significantly improved asthma prescribing and communication behaviours of primary care paediatricians in the USA. We tested the feasibility and acceptability of a modified PACE program with Australian general practitioners (GP) and measured its impact on self-reported consulting behaviours in a pilot study. Recruitment took place through a local GP division. Twenty-five GP completed two PACE Australia workshops, which incorporated paediatric asthma management consistent with Australian asthma guidelines and focussed on effective communication strategies. Program feasibility, usefulness and perceived benefit were measured by questionnaires before the workshop and 1 month later, and an evaluation questionnaire after each workshop. GP were universally enthusiastic and supportive of the workshops. The most useful elements they reported were communication skills, case studies, device demonstrations and the toolkit provided. GP self reports of the perceived helpfulness of the key communication strategies and their confidence in their application and reported frequency of use increased significantly after the workshops. The PACE program shows promise in improving the way in which Australian GP manage asthma consultations, particularly with regard to doctor-patient communication. The impact ofthe modified PACE Australia program on the processes and outcomes ofGP care ofchildren with asthma is now being measured in a randomised controlled trial.

Respiratory health effects of exposure to low-NOx unflued gas heaters in the classroom: a double-blind, cluster-randomized, crossover study

BACKGROUND

There are long-standing concerns about adverse effects of gas appliances on respiratory health. However, the potential adverse effect of low-NOx (nitrogen oxide) unflued gas heaters on children's health has not been assessed.

OBJECTIVES

Our goal was to compare the respiratory health effects and air quality consequences of exposure to low-NOx unflued gas heaters with exposure to non-indoor-air-emitting flued gas heaters in school classrooms.

METHODS

We conducted a double-blind, cluster-randomized, crossover study in 400 primary school students attending 22 schools in New South Wales, Australia. Children measured their lung function and recorded symptoms and medication use twice daily. Nitrogen dioxide (NO2) and formaldehyde concentrations were measured in classrooms using passive diffusion badges.

RESULTS

NO2 concentrations were, on average, 1.8 times higher [95% confidence interval (CI), 1.6-2.1] and formaldehyde concentrations were, on average, 9.4 ppb higher (95% CI, 5.7-13.1) during exposure to unflued gas versus flued gas heaters. Exposure to the unflued gas heaters was associated with increased cough reported in the evening [odds ratio (OR) = 1.16; 95% CI, 1.01-1.34] and wheeze reported in the morning (OR = 1.38; 95% CI, 1.04-1.83). The association with wheeze was greater in atopic subjects. There was no evidence of an adverse effect on lung function.

CONCLUSIONS

We conclude that classroom exposure to low-NOx unflued gas heaters causes increased respiratory symptoms, particularly in atopic children, but is not associated with significant decrements in lung function. It is important to seek alternative sources of heating that do not have adverse effects on health.

The association of comorbid anxiety and depression with asthma-related quality of life and symptom perception in adults

BACKGROUND AND OBJECTIVE

There are limited data on the association and interaction between anxiety and depression comorbidity and asthma-related quality of life (AQOL) and symptom perception. This study evaluated these associations in patients subsequent to an emergency department (ED) visit for asthma.

METHODS

This was a cross-sectional study of 110 (38 male) adult asthma patients (mean age 42 years), who had visited an ED in the previous 18 months. Participants completed the hospital anxiety and depression scale, measures of AQOL and the asthma symptom checklist.

RESULTS

Depression symptoms independently showed a significant negative association with AQOL after controlling for depression/anxiety, age, gender, smoking status and ED visits in the previous 12 months (ED-12). Overall, anxiety and depression symptoms accounted for 28.3% of the variance in AQOL. Greater anxiety was associated with increased perception of asthma-specific panic-fear and hyperventilation symptoms during an asthma attack, irrespective of depression status. Categorical analyses of groups of patients, differentiated by psychometric properties on the hospital anxiety and depression scale (anxiety vs normal, anxiety and depression vs normal depression) confirmed most results. However, for the anxiety group there was a significant association with the AQOL domains of emotional functioning and response to environmental stimuli, after controlling for depression symptoms.

CONCLUSIONS

The negative association of depression symptom scores with AQOL and of anxiety with increased panic-fear and hyperventilation symptoms suggests a potential role for interventions addressing this psychological comorbidity, in order to improve AQOL.

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.