Objective: To compare low birth weight (LBW) (< 2,500g) between infants born to adolescent and adult mothers in Iquitos, Peru. Methods: A random sample of 4,467 birth records was collected. Multivariate analyses were performed to compare both the proportion of LBW and mean birth weight of newborns of adolescents (10-14 yrs, 15-19 yrs) and adults (≥ 20 yrs) and then for primiparous mothers only. Results: For all mothers, all adolescents had significantly greater odds of having a LBW infant than adults. For primiparous mothers, the same was true only for 10-14 year-olds. There were significant differences in mean birth weight between adults and both early and late adolescent age groups. Discussion: Results provide evidence for increased risk of LBW in adolescents, especially early adolescents. Further research is needed on elucidating the basis of this disparity, especially in terms of physiological and behavioural determinants. / Objectif : Comparer le faible poids de naissance (FPN) (< 2,500g) entre les nouveaux-nés d'adolescentes et ceux d'adultes à Iquitos, Pérou.Méthodes : Un échantillon aléatoire de 4,467 dossiers de naissance a été rassemblé. Les analyses multivariables ont été exécutées pour comparer la proportion de FPN et la moyenne poids de naissance parmi les nouveaux-nés d'adolescentes (10-14 ans, 15-19 ans) et ceux d'adultes (≥ 20 ans) et ensuite en considérant que les mères primigestes.Résultats : Parmi toutes mères, toutes adolescentes avaient des chances plus grandes d'avoir un nouveau-né de FPN que les adultes. Parmi les primigestes, ceci était vrai que pour le groupe 10-14 ans. La moyenne poids de naissance parmi tous les groupes d'adolescentes était significativement inférieure à celle des adultes.Discussion : Ces résultats fournis des preuves du risque accru de FPN parmi les adolescentes, surtout les adolescentes plus jeunes (10-14 ans). L'étude supplémentaire est requise pour établir si cette divergence est fonction de physiologie ou comportement.

Air pollution is an important determinant of population health. The World Health Organization estimates that air pollution is responsible for nearly 2% of all deaths globally. The current research is aimed at determining the specific components of air pollution that are most likely linked to increased risk of mortality. Since one air pollutant is unlikely to be emitted by itself, various mixtures of air pollutants must be investigated. It is possible that the health effects of one pollutant in the mixture might be larger than the health effects of another. The current research focuses on the relationship between multiple air pollutants and mortality in the general population. By examining combinations of pollutants, it is possible to isolate, to a certain extent, the effects of individual pollutants. The population health outcomes investigated include mortality from cardiopulmonary conditions, lung cancer, and all causes combined. Air pollution data from various metropolitan regions in the U.S. were linked to the health outcomes of individuals living in these areas. Characteristics of individuals that may affect the relationship between air pollution and mortality, such as age, sex, smoking history, alcohol use, were obtained from the American Cancer Society Cancer Prevention Study II cohort. Nearly 1.2 million adults were enrolled in this study in 1982, and have been followed up on an on-going basis. This study suggests that sulfate and, more broadly, fine particulate matter may be the most important contributors to excess risk of all-cause, cardiopulmonary, and lung cancer mortality.

Objective. We derive a preliminary clinical decision rule to identify which patients with chest pain can be safely discharged without cardiac stress testing. Methods. We prospectively enrolled patients over 24 years of age with chest pain. The primary outcome was acute myocardial infarction, revascularization, or 30-day mortality. Results. We enrolled 640 patients. Characteristics were: mean age 59.6 years, 40.2% female and 21.9% history of acute myocardial infarction. There were 87 positive outcomes. We derived a rule which consisted of 5 variables: known coronary artery disease, age &ge; 55 years, acute ischemic changes on electrocardiogram, cardiac troponin T &ge; 0.01 ng/mL, and diaphoresis. The rule was 100% (95% CI 96-100%) sensitive and 25% (22-25%) specific for adverse cardiac events. Conclusion. We derived a preliminary decision rule that is highly sensitive for adverse cardiac events. Additional research is required to derive a definitive decision rule.

Sudden infant death syndrome (SIDS) constitutes an increasing proportion of infant deaths, and twins have a higher risk of SIDS than singletons. This retrospective cohort study, based on the 1995-1997 Matched Multiple Birth File of the United States, examined risk factors of SIDS and non-SIDS deaths using generalized estimating equations, and investigated competing risks of SIDS using survival analysis. The three unique characteristics of twins, namely birth weight discordance, birth order within pairs, and sex combinations, were not associated with SIDS, while they were related to non-SIDS deaths. Lower maternal education, younger maternal age, and maternal smoking during pregnancy were the strongest risk factors of SIDS among twins. Preterm birth and fetal growth restriction were determinants of infant deaths, including both SIDS and non-SIDS deaths. In conclusion, social factors and common biological factors are important risk factors for SIDS among twins while the biological factors unique to twins are not.

Objective. There are currently no recommendations on the use of surveillance mammography for women who have undergone breast reconstruction following mastectomy. The objective of this study is to address the needs of this population of women with regards to the inclusion of ipsilateral surveillance mammography in their regular surveillance. Methods. A multimethod approach including (1) a systematic review, (2) a population based cohort study, and (3) an economic analysis was conducted to evaluate this issue. Results. The systematic review found only case reports and case series' addressing the role of surveillance mammography in women who have undergone breast reconstruction following mastectomy. These studies documented that local recurrence does occur in reconstructed breasts, and that these may be detected by surveillance mammography. In the cohort component of the study, variation in practice was found as 39% of women in the cohort underwent at least one surveillance mammogram of their reconstructed breast. Inference on the effectiveness of surveillance mammography of the reconstructed breast could not be made. The economic analysis found that in order to be cost effective, a reduction in metastatic risk of 3.34% following local recurrence detected by surveillance mammography was required. Conclusion. The findings from this thesis point to two recommendations. First, until stronger evidence becomes available, it is prudent to recommend that women with breast reconstruction undergo yearly bilateral surveillance mammography. Second, future research is required to review patient outcomes and provide the needed clinical evidence to support this practice.

Background. Whether to continue or to discontinue oral anticoagulation therapy (OAT) after 6 months of treatment to prevent recurrent or fatal events in unprovoked VTE patients is currently controversial. We sought to develop and internally validate a clinical prediction rule (CPR) to identify patients at low risk of recurrent VTE (at most 3% annual risk) for whom OAT could be safely discontinued. Methods. Univariate and multivariate analysis techniques were used to identify the best set of predictor variables. Results and conclusions. We derived and internally validated a CPR for females comprised of D-Dimer over 250 ug/L, post-thrombotic signs present, older age (over 65 years) and obesity (BMI over 30 kg/m2). Women with one or none of the four aforementioned clinical predictors had an annual risk of recurrent VTE of 1.6% and may be able to discontinue OAT. None of the models for males was shown to be safe.

The present study investigated the association between gaseous air pollutants and mortality and morbidity due to specific cardiovascular conditions in the elderly population in Vancouver, British Columbia. Time-series analysis was utilized to evaluate the daily levels of carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), and ozone (O3) in relation to cardiovascular hospital admissions and deaths between January 1985 and March 1999. Results showed significant associations between CO and ischemic heart disease and heart failure admissions, NO 2 and all cardiovascular hospitalizations and stroke deaths and between SO2 and heart failure hospital admissions. Vancouver air pollutant levels were well below the Canadian National Ambient Air Quality Objectives maximum acceptable levels. However the results of this study showed a negative influence on the population's health suggesting that a re-evaluation of these standards may be necessary.

The primary goal of this research was to identify whether the structure of the network of individuals who inject drugs and share drug injection equipment in Winnipeg, Canada may be scale-free. Recently, sexual networks have been found to be scale-free in a wide range of populations which has important implications in terms of the spread of disease. Epidemic thresholds do not exist in a scale-free network and as a result even weakly infectious viruses can spread easily through a network of contacts. By analogy, identifying the structure of contacts formed by individuals in other infectious disease networks may also help to define transmission dynamics which can be used to develop more effective interventions. In a series of three papers the scientific literature from a variety of disciplines including physics, epidemiology, mathematical, biological and computer sciences relating to scale free networks is reviewed and integrated; methods used to identify scale-free networks are tested and compared among individuals who inject drugs in Winnipeg, Canada using data from two network studies (a pilot study and a main study); and potential new interventions that could be implemented to help reduce the transmission of HIV and HCV among individuals who inject drugs by the existing needle exchange program are recommended based on the results. Keywords: Scale-free networks, injection drug use, epidemiology, network analysis

Objective. To apply the concept of environmental press to study the relationship between the built environment and physical activity among older adults living in long-term care (LTC) homes. Methods. This cross-sectional study used a questionnaire to assess physical activity among 78 seniors living in seven LTC homes. Secondary data analysis of existing environmental scans divided the homes into two levels of environmental press. Type and duration of physical activity were compared between seniors living in homes with appropriate and inappropriately high levels of environmental press. Results. Seniors' total amount of physical activity did not differ between the two groups of homes. Seniors living in homes with appropriate environmental press were more likely to receive physiotherapy and less likely to stretch alone than those living in homes with inappropriately high environmental press. Conclusions. Environmental press did not significantly influence seniors' total participation in physical activity. Validated environmental assessments tailored to LTC settings are needed.

Characterizing adverse health affects associated with endocrine disruptors has proved difficult as few epidemiological studies have utilized validated exposure data or adequate knowledge of exposed individuals within the general population (Landrigan et al., 2003; WHO, 2002). Given the pervasive nature of endocrine disruptors and their ability to bioaccumulate in food chains, these compounds may constitute a serious public health problem with widespread consequences. In order to characterize which populations are at risk of the potentially detrimental effects of endocrine disruptors, a series of analytical tools, including classification and regression trees, descriptive analysis and stratified regression models, were applied to the bio-monitoring data collected by the US National Health and Nutrition Examination Survey (NHANES) for the years of 1999 to 2002. Overall, 7.8-33.7% of the variability in exposure to non-persistent endocrine disrupting chemicals could be accounted for by selected variables such age, race/ethnicity, country of birth, occupation, marital status, and rooms treated for pests. However, these results should be interpreted with caution as a linear approach to creatinine adjustment increased the r2 value in these models. In fact, very little of the variability could be accounted for using the aforementioned variables, indicating that exposures to non-persistent chemicals are difficult to predict using proxy measures. For persistent chemicals, models were successful in predicting between 22.53-51.21% of the variability in exposure levels, with age proving to be the strongest predictor. Other variables found to significantly predict exposures were race, country of birth, BMI, and marital status. Despite the fact that the predictors determined in this study are often tied to a wide range of risk factors for disease, other chemical exposures, and socioeconomic factors, these results will allow future epidemiological studies and public health interventions to effectively target exposed populations within the general public.