Frances L. Garden

Impact of Urban Sprawl on Overweight, Obesity, and Physical Activity in Sydney, Australia

Obesity and inadequate physical activity are major risk factors for many diseases. The built environment plays an important role in influencing participation in physical activity. We aimed to determine whether urban sprawl in Sydney, Australia is associated with overweight/obesity and levels of physical activity. We used a cross-sectional multilevel study design to relate urban sprawl (based on population density) measured at an area level to overweight/obesity and levels of physical activity measured at an individual level whilst controlling for individual and area level covariates in metropolitan Sydney. Individual level data were obtained from the 2002 and 2003 New South Wales Population Health Survey. We had information on 7,290 respondents. The mean population density was 2,168 persons per square kilometer (standard deviation = 1,741, range = 218–7,045). After controlling for individual and area level covariates, for an inter-quartile increase in sprawl, the odds of being overweight was 1.26 (95% CI = 1.10–1.44), the odds of being obese was 1.47 (95% CI = 1.24–1.75), the odds of inadequate physical activity was 1.38 (95% CI = 1.21–1.57), and the odds of not spending any time walking during the past week was 1.58 (95% CI = 1.28–1.93). Living in more sprawling suburbs increases the risk of overweight/obesity and inadequate physical activity despite the relatively low levels of urban sprawl in metropolitan Sydney. Modifications to the urban environment to increase physical activity may be worthwhile.

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.

Atopy phenotypes in the Childhood Asthma Prevention Study (CAPS) cohort and the relationship with allergic disease

Atopy in early life is heterogeneous in timing of onset, remission and persistence and in the nature of specific sensitization to allergens. However, this heterogeneity is not well characterized.

Breastfeeding, asthma, and allergy: a tale of two cities

To cite this article: Brew BK, Kull I, Garden F, Almqvist C, Bergström A, Lind T, Webb K, Wickman M, Marks GB. Breastfeeding, asthma, and allergy: a tale of two cities. Pediatric Allergy Immunology 2012: 23: 75–82.

Body Mass Index (BMI) Trajectories from Birth to 11.5 Years: Relation to Early Life Food Intake

Recent research has shown that the pattern of change over time, or trajectory, of body mass index (BMI) varies among children. However, the factors that underlie the heterogeneity in these trajectories remain largely unexplored. Our aim was to use a growth mixture model to empirically identify classes of BMI trajectories (from birth to 11.5 years) and examine the effects of breastfeeding, introduction of solids, as well as food and nutrient intake at 18 months on these BMI trajectories. We identified three BMI growth trajectories between birth and age 11.5 years, separately in boys and girls. Breastfeeding duration less than six months and the early introduction of solids did not adversely influence BMI trajectories in our sample but high intakes of meat, particularly high fat varieties, and high intakes of carbohydrate at age around 18 months were associated with a high BMI trajectory in boys. It is not clear whether these dietary factors confer a direct risk of higher BMI in childhood or are markers for other dietary patterns that are present early and/or develop through childhood and contribute to higher BMI.

Infant and early childhood dietary predictors of overweight at age 8 years in the CAPS population

Background/Objectives:Programs to address obesity are a high priority for public policy especially for young children. Research into dietary determinants of obesity is challenging but important for rational planning of interventions to prevent obesity, given that both diet and energy expenditure influence weight status. We investigated whether early life dietary factors were predictive of weight status at 8 years in a cohort of Australian children.Subjects/Methods:We used data from the Childhood Asthma Prevention Study—a birth cohort at high risk of asthma. Dietary data (3-day weighed food records) were collected at 18 months and height, weight and waist circumference were collected at 8 years. We assessed the relationship between dietary predictor variables and measures of adiposity using linear regression.Results:Intakes of protein, meat and fruit at age 18 months were positively associated with measures of adiposity at age 8 years, namely, body mass index and/or waist circumference. We also showed a significant negative relationship between these measures of adiposity at 8 years and intake at 18 months of dairy foods as a percent of total energy, and intake of energy dense cereal-based foods such as cookies and crackers.Conclusions:This birth cohort study with rigorous design, measures and analyses, has shown a number of associations between early dietary intake and subsequent adiposity that contribute to the growing evidence base in this important field.

Effects of early cat or dog ownership on sensitisation and asthma in a high‐risk cohort without disease‐related modification of exposure

Variation in the observed association between pet ownership and allergic disease may be attributable to selection bias and confounding. The aim of this study was to suggest a method to assess disease-related modification of exposure and second to examine how cat acquisition or dog ownership in early life affects atopy and asthma at 5 years. Information on sociodemographic factors and cat and dog ownership was collected longitudinally in an initially cat-free Australian birth cohort based on children with a family history of asthma. At age 5 years, 516 children were assessed for wheezing, and 488 for sensitisation. Data showed that by age 5 years, 82 children had acquired a cat. Early manifestations of allergic disease did not foreshadow a reduced rate of subsequent acquisition of a cat. Independent risk factors for acquiring a cat were exposure to tobacco smoke at home odds ratio (OR) 1.92 [95% confidence interval (CI) 1.13, 3.26], maternal education < or =12 years OR 1.95 [1.08, 3.51] and dog ownership OR 2.23 [1.23, 4.05]. Cat or dog exposure in the first 5 years was associated with a decreased risk of any allergen sensitisation, OR 0.50 [0.28, 0.88] but no association with wheeze OR 0.96 [0.57, 1.61]. This risk was not affected by age at which the cat was acquired or whether the pet was kept in- or outdoors. In conclusion, cat or dog ownership reduced the risk of subsequent atopy in this high-risk birth cohort. This cannot be explained by disease-related modification of exposure. Public health recommendations on the effect of cat and dog ownership should be based on birth cohort studies where possible selection bias has been taken into account.

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. New objective childhood asthma phenotypes show transitioning between phenotypes is common in early not late childhood http://ow.ly/RT5qz

Weight gain in infancy is associated with carotid extra-medial thickness in later childhood

OBJECTIVE Early life is an important period for determining future risk of cardiovascular disease. Carotid extra-medial thickness is a novel noninvasive measure that estimates arterial adventitial thickness, information concerning vascular health not captured by assessment of arterial intima-media thickness alone. We sought to determine whether fetal growth and early postnatal growth are associated with carotid extra-medial thickness in 8 year old children. METHODS Carotid extra-medial thickness was assessed by high-resolution ultrasound in 379 non-diabetic children aged 8-years, with complete data for birth weight, gestational age, early postnatal weight gain and carotid extra-medial thickness. RESULTS Weight gain during infancy, from birth to 18 months of age, was significantly and positively associated with carotid EMT (11 μm per kg length-adjusted weight gain [95% CI 3, 18], P=0.007). This association was significantly stronger in boys than girls (Pheterogeneity=0.005). By contrast, there was no significant association between birth weight and carotid EMT (6 μm/kg birth weight [95% CI -12, 24], P=0.51). CONCLUSION Excessive weight gain during infancy is associated with increased carotid extra-medial thickness, indicating that the alterations to the vasculature associated with excessive early postnatal growth likely include arterial adventitial thickening.

Time-Based Measurement of Personal Mite Allergen Bioaerosol Exposure over 24 Hour Periods.

Allergic diseases such as asthma and rhinitis are common in many countries. Globally the most common allergen associated with symptoms is produced by house dust mites. Although the bed has often been cited as the main site of exposure to mite allergens, surprisingly this has not yet been directly established by measurement due to a lack of suitable methods. Here we report on the development of novel methods to determine the pattern of personal exposure to mite allergen bioaerosols over 24-hour periods and applied this in a small field study using 10 normal adults. Air was sampled using a miniature time-based air-sampler of in-house design located close to the breathing zone of the participants, co-located with a miniature time-lapse camera. Airborne particles, drawn into the sampler at 2L/min via a narrow slot, were impacted onto the peripheral surface of a disk mounted on the hour-hand of either a 12 or 24 hour clock motor. The impaction surface was either an electret cloth, or an adhesive film; both novel for these purposes. Following a review of the time-lapse images, disks were post-hoc cut into subsamples corresponding to eight predetermined categories of indoor or outdoor location, extracted and analysed for mite allergen Der p 1 by an amplified ELISA. Allergen was detected in 57.2% of the total of 353 subsamples collected during 20 days of sampling. Exposure patterns varied over time. Higher concentrations of airborne mite allergen were typically measured in samples collected from domestic locations in the day and evening. Indoor domestic Der p 1 exposures accounted for 59.5% of total exposure, whereas total in-bed-asleep exposure, which varied 80 fold between individuals, accounted overall for 9.85% of total exposure, suggesting beds are not often the main site of exposure. This study establishes the feasibility of novel methods for determining the time-geography of personal exposure to many bioaerosols and identifies new areas for future technical development and clinical applications.