The effects of air pollution on asthma hospital admissions in Adelaide, South Australia, 2003-2013: time-series and case-crossover analyses.

BACKGROUND: Air pollution can have adverse health effects on asthma sufferers, but the effects vary with geographic, environmental and population characteristics. There has been no long time-series study in Australia to quantify the effects of environmental factors including pollen on asthma hospitalizations. OBJECTIVES: This study aimed to assess the seasonal impact of air pollutants and aeroallergens on the risk of asthma hospital admissions for adults and children in Adelaide, South Australia. METHODS: Data on hospital admissions, meteorological conditions, air quality and pollen counts for the period 2003-2013 were sourced. Time-series analysis and case-crossover analysis were used to assess the short-term effects of air pollution on asthma hospitalizations. For the time-series analysis, generalized log-linear quasi-Poisson and negative binomial regressions were used to assess the relationships, controlling for seasonality and long-term trends using flexible spline functions. For the case-crossover analysis, conditional logistic regression was used to compute the effect estimates with time-stratified referent selection strategies. RESULTS: A total of 36,024 asthma admissions were considered. Findings indicated that the largest effects on asthma admissions related to PM2.5 , NO2 , PM10 and pollen were found in the cool season for children (0-17 years), with the 5-day cumulative effects of 30.2% (95% CI: 13.4-49.6%), 12.5% (95% CI: 6.6-18.7%), 8.3% (95% CI: 2.5-14.4%) and 4.2% (95% CI: 2.2-6.1%) increases in risk of asthma hospital admissions per 10 unit increments, respectively. The largest effect for ozone was found in the warm season for children with the 5-day cumulative effect of an 11.7% (95% CI: 5.8-17.9%) increase in risk of asthma hospital admissions per 10 ppb increment in ozone level. CONCLUSION: Findings suggest that children are more vulnerable and the associations between exposure to air pollutants and asthma hospitalizations tended to be stronger in the cool season compared to the warm season, with the exception of ozone. This study has important public health implications and provides valuable evidence for the development of policies for asthma management.

Optimal designs for 2-color microarray experiments.

Statisticians can play a crucial role in the design of gene expression studies to ensure the most effective allocation of available resources. This paper considers Pareto optimal designs for gene expression studies involving 2-color microarrays. Pareto optimality enables the recommendation of designs that are particularly efficient for the effects of most interest to biologists. This is relevant in the microarray context where analysis is typically carried out separately for those effects. Our approach will allow for effects of interest that correspond to contrasts rather than solely considering parameters of the linear model. We further develop the approach to cater for additional experimental considerations such as contrasts that are of equal scientific interest. This amounts to partitioning all relevant contrasts into subsets of effects that are of equal importance. Based on the partitions, a penalty is employed in order to recommend designs for complex and varied microarray experiments. Finally, we address the issue of gene-specific dye bias. We illustrate using studies of leukemia and breast cancer.

Gene profiling for determining pluripotent genes in a time course microarray experiment.

In microarray experiments, it is often of interest to identify genes which have a prespecified gene expression profile with respect to time. Methods available in the literature are, however, typically not stringent enough in identifying such genes, particularly when the profile requires equivalence of gene expression levels at certain time points. In this paper, the authors introduce a new methodology, called gene profiling, that uses simultaneous differential and equivalent gene expression level testing to rank genes according to a prespecified gene expression profile. Gene profiling treats the vector of true gene expression levels as a linear combination of appropriate vectors, for example, vectors that give the required criteria for the profile. This gene profile model is fitted to the data, and the resulting parameter estimates are summarized in a single test statistic that is then used to rank the genes. The theoretical underpinnings of gene profiling (equivalence testing, intersection-union tests) are discussed in this paper, and the gene profiling methodology is applied to our motivating stem-cell experiment.

Consumption of untreated tank rainwater and gastroenteritis among young children in South Australia.

BACKGROUND: Tank rainwater is a source of untreated drinking water in Australia and elsewhere. The aim of this study was to determine whether the risk of gastroenteritis among children who drank tank rainwater differed from that of children who drank treated public mains water. METHODS: A cohort study of 1,016 4- to 6-year old children who drank rainwater or treated mains water in rural South Australia was undertaken in 1999. Parents kept a daily diary of their child's gastrointestinal symptoms and water consumption for a period of 6 weeks. Data on respiratory illness and other risk factors for gastroenteritis were also collected. RESULTS: The incidence of gastroenteritis among children was 3.8-5.3 episodes per child-year, but most episodes (60%) lasted just 1 day. No increase in odds of gastroenteritis was observed among children who drank rainwater compared with treated mains water. The adjusted odds ratio for gastroenteritis associated with rainwater consumption compared with mains consumption was 0.84 (95% confidence interval 0.63-1.13). CONCLUSIONS: Gastroenteritis was found to be a significant cause of morbidity among young children. Young children, who were regular consumers of tank rainwater, were at no greater odds of gastroenteritis than those who drank treated public mains water.

Does dog or cat ownership lead to increased gastroenteritis in young children in South Australia?

The aim of this study was to investigate the relationship between dog and cat ownership and gastroenteritis in young children. A diary study of 965 children aged 4-6 years living in rural or semi-rural South Australia was undertaken. Data were collected on pet ownership, drinking water and other risk factors for gastroenteritis. Overall 89% of households had pets and dog ownership was more common than cat ownership. The multivariable models for gastroenteritis and pet ownership indicated that living in a household with a dog or cat was associated with a reduced risk of gastroenteritis (adj. OR 0.71, 95% CI 0.55-0.92; OR 0.70, % CI 0.51-0.97 respectively). This paper adds to the evidence that pets are not a major source of gastroenteritis in the home and lends support to the health benefits of pet ownership. However, this must be weighed against the potential negative consequences, such as dog bites, particularly for this age group.

Factorial and time course designs for cDNA microarray experiments.

Microarrays are powerful tools for surveying the expression levels of many thousands of genes simultaneously. They belong to the new genomics technologies which have important applications in the biological, agricultural and pharmaceutical sciences. There are myriad sources of uncertainty in microarray experiments, and rigorous experimental design is essential for fully realizing the potential of these valuable resources. Two questions frequently asked by biologists on the brink of conducting cDNA or two-colour, spotted microarray experiments are 'Which mRNA samples should be competitively hybridized together on the same slide?' and 'How many times should each slide be replicated?' Early experience has shown that whilst the field of classical experimental design has much to offer this emerging multi-disciplinary area, new approaches which accommodate features specific to the microarray context are needed. In this paper, we propose optimal designs for factorial and time course experiments, which are special designs arising quite frequently in microarray experimentation. Our criterion for optimality is statistical efficiency based on a new notion of admissible designs; our approach enables efficient designs to be selected subject to the information available on the effects of most interest to biologists, the number of arrays available for the experiment, and other resource or practical constraints, including limitations on the amount of mRNA probe. We show that our designs are superior to both the popular reference designs, which are highly inefficient, and to designs incorporating all possible direct pairwise comparisons. Moreover, our proposed designs represent a substantial practical improvement over classical experimental designs which work in terms of standard interactions and main effects. The latter do not provide a basis for meaningful inference on the effects of most interest to biologists, nor make the most efficient use of valuable and limited resources.

A three-sample multiple-recapture approach to census population estimation with heterogeneous catchability.

"A central assumption in the standard capture-recapture approach to the estimation of the size of a closed population is the homogeneity of the 'capture' probabilities. In this article we develop an approach that allows for varying susceptibility to capture through individual parameters using a variant of the Rasch model from psychological measurement situations. Our approach requires an additional recapture. In the context of census undercount estimation, this requirement amounts to the use of a second independent sample or alternative data source to be matched with census and Post-Enumeration Survey (PES) data.... We illustrate [our] models and their estimation using data from a 1988 dress-rehearsal study for the 1990 census conducted by the U.S. Bureau of the Census, which explored the use of administrative data as a supplement to the PES. The article includes a discussion of extensions and related models."

[Epidemiologic studies after the disaster in Czernobyl in the population of children in the Krakow region]. / Badania epidemiologiczne po awarii w Czarnobylu w populacji dzieci w regionie krakowskim.

In 1989-1990 the epidemiologic studies about the impact of of Czarnobyl events on the health of children in Kraków and Nowy Sacz region were performed. The morphologic and functional changes of thyroid gland in children were estimated. Almost 90% of children in both districts received the iodine preparations for prophylactic reason. The mean time of intake was between 5-10 days following the Czarnobyl explosion. There were no relationship between the dose of iodine absorbed during prophylactic action and incidence of goiter. The prevalence of goiter amounted to 34.8-47.6% in boys and girls consecutively in Kraków district and 53.8-70.5% in Nowy Sacz. No hormonal changes in T3, T4 and TSH serum concentration were found in children with goiter and those without goiter. The complications after iodine intake were transient and seen only in a small number of children.

Diffusing capacity predicts morbidity and mortality after pulmonary resection.

Patients who are considered for major pulmonary resection are normally evaluated by spirometry and clinical assessment. Despite this, the morbidity and mortality rates are high after these operations. We retrospectively reviewed results of lung resection performed during a period of 7.5 years in 237 patients to identify other important predictors of morbidity and mortality. There were 144 male and 93 female patients with a mean age of 59.4 +/- 11.4 years. The indication for operation was lung cancer in 199 (76 stage I, 34 stage II, 89 stage IIIA-B), benign disease in 34, and metastatic disease from other primary tumors in four. Lobectomy or bilobectomy was performed in 164 patients and pneumonectomy in 73. Data on 38 preoperative and operative risk factors were correlated with information on 24 postoperative events grouped into four major categories: death, pulmonary complications, cardiovascular complications, and other problems. Logistic regression analysis and chi 2 analysis were used to identify the relationship of the preoperative risk factors to the grouped postoperative complications. The diffusing capacity of the lung for carbon monoxide was the most important predictor of mortality (p less 0.01) and was the sole predictor of postoperative pulmonary complications (p less than 0.005). This diffusing capacity can reveal the existence of emphysematous changes in the lung, even when spirometric values are acceptable, and it usually should be a part of the evaluation of patients being considered for pulmonary resection.