[show abstract][hide abstract] ABSTRACT: To assess the risk of neonatal mortality and morbidity in vertex-vertex second twins according to mode of delivery and birth weight.
Data from a historical cohort study based on a twin registry in the US (1995-1997) were used. Multivariate logistic regression was used to control for maternal age, race, marital status, cigarette smoking during pregnancy, parity, medical complications, gestational age, and other confounders.
A total of 86 041 vertex-vertex second twins were classified into two groups: second twins delivered by cesarean section after cesarean delivery of first twin (C-C) (43.0%), second twins whose co-twins delivered vaginally (V-X) (57.0%). In infants of birth weight>or=2500 g group, the risks of noncongenital anomaly-related death (adjusted odds ratio (aOR): 4.64, 95% confidence interval (95% CI): 1.90, 13.92), low Apgar score (aOR: 2.39, 95% CI: 1.43, 4.14), and ventilation use (aOR: 1.31, 95% CI: 1.18, 1.47) were higher in the V-X group compared with the C-C group. No asphyxia-related neonatal deaths occurred in C-C group, whereas the incidence of this death was 0.04% in the V-X group.
The risks of neonatal mortality and morbidity are increased in vertex-vertex second twins with birth weight>or=2500 g whose co-twins delivered vaginally compared with second twins delivered by cesarean section after cesarean delivery of first twin.
Journal of Perinatology 01/2006; 26(1):3-10. · 2.25 Impact Factor
[show abstract][hide abstract] ABSTRACT: Assess associations between short-term exposure to gaseous pollutants and asthma hospitalisation among boys and girls 6 to12 years of age.
A bi-directional case-crossover analysis was used. Conditional logistic regression models were fitted to the data for boys and girls separately. Exposures averaged over periods ranging from one to seven days were used to assess the effects of gaseous pollutants on asthma hospitalisation. Estimated relative risks for asthma hospitalisation were calculated for an incremental exposure corresponding to the interquartile range in pollutant levels, adjusted for daily weather conditions and concomitant exposure to particulate matter.
Toronto, Ontario, Canada.
A total of 7319 asthma hospitalisations for children 6 to 12 years of age (4629 for boys and 2690 for girls) in Toronto between 1981 and 1993.
A significant acute effect of carbon monoxide on asthma hospitalisation was found in boys, and sulphur dioxide showed significant effects of prolonged exposure in girls. Nitrogen dioxide was positively associated with asthma admissions in both sexes. The lag time for certain gaseous pollutant effects seemed to be shorter in boys (around two to three days for carbon monoxide and nitrogen dioxide), as compared with girls (about six to seven days for sulphur dioxide and nitrogen dioxide). The effects of gaseous pollutants on asthma hospitalisation remained after adjustment of particulate matter. The data showed no association between ozone and asthma hospitalisation in children.
The study showed positive relations between gaseous pollutants (carbon monoxide, sulphur dioxide, and nitrogen dioxide) at comparatively low levels and asthma hospitalisation in children, using bi-directional case-crossover analyses. Though, the effects of certain specific gaseous pollutants were found to vary in boys and girls.
Journal of Epidemiology & Community Health 02/2003; 57(1):50-5. · 3.39 Impact Factor
[show abstract][hide abstract] ABSTRACT: The authors examined the interactive effect of smoking and pets at home on the incidence of asthma and the difference between sexes. The longitudinal data from the first two cycles of the National Population Health Survey, conducted in Canada, were used. A total of 12,636 subjects who reported no asthma at baseline were included in the analysis. The 2-yr cumulative incidence of asthma was higher in females than in males. Female sex and household pets demonstrated a significant interaction in the development of asthma. After adjustment for age, immigration and history of allergy, the odds ratio for smoking in relation to the asthma incidence was 2.50 (95% confidence interval: 1.24-5.05) for females who had pets at home and close to unity for those who had no pets. The incidence of asthma was not associated with smoking status and household pets in males. These results indicate that smoking, having pets at home and other environmental factors can partly explain asthma morbidity among female Canadians.
European Respiratory Journal 12/2002; 20(5):1162-6. · 6.36 Impact Factor
[show abstract][hide abstract] ABSTRACT: A study was undertaken to investigate the mechanisms by which socioeconomic status may influence asthma morbidity in Canada.
A total of 2968 schoolchildren aged 5-19 years with reported asthma were divided into three family income ranges. Hospital visits and risk factors for asthma, ascertained by questionnaire, were compared between the three groups.
The mean (SE) annual period prevalence of a hospital visit was 25.0 (3.1)% among schoolchildren with household incomes of less than $20 000 Canadian compared with 16.0 (1.3)% among those with incomes of more than $60 000 (p<0.05). Students with asthma from lower income households were more likely to be younger and exposed to environmental tobacco smoke and cats, and their parents were more likely to have a lower educational attainment and be unmarried (p<0.05). Across all income groups, younger age, lower parental education, having unmarried parents, and regular exposure to environmental tobacco smoke were each associated with an increase in risk of a hospital visit (p<0.05). No increased risk was detected due to sex, having pets, and not taking dust control measures. Although not statistically significant at p<0.05, there may have been an interactive effect between income and susceptibility to environmental tobacco smoke. In the lower income group those children who were regularly exposed to second hand smoke had a 79% higher risk of a hospital visit compared with a 45% higher risk in the higher income group. In a logistic regression model the association between income and hospital visit was no longer significant after adjusting for differences in reported exposure to passive smoking.
Socially disadvantaged Canadian schoolchildren have increased asthma morbidity. Exposure to cigarette smoke appears to be one important explanation for this observation.
[show abstract][hide abstract] ABSTRACT: Asthma is an important determinant of hospitalization. The study aims to examine the modifying effects of demographic and socioeconomic factors on the relationship between asthma and the overall number of hospitalizations.
We examined the data on 17,601 Canadians who were > or = 12 years of age to explore the combined effects of asthma and other factors on hospitalization within the context of a publicly funded health-care system. Asthma was determined by an affirmative response to the question: "Do you have asthma diagnosed by a health professional?" The subjects also were asked whether they had been an overnight patient in a hospital during the past 12 months.
Asthma as a risk factor explained 3.7% of all hospitalizations of men and 2.4% of all hospitalizations of women. Overall, hospitalization was positively associated with female gender, old age, and low household income. The odds ratio for asthma as a risk factor for overall hospitalization (ie, hospitalization for any reason and all causes, not only for asthma) was greater for younger men than for older men, for less-educated women than for well-educated women, and for men with middle or high incomes than for men with low incomes.
These results suggest that demographic and socioeconomic factors play a role in the relationship between asthma and the overall number of hospitalizations, with certain population subgroups being at greater risk of hospitalization in relation to asthma.
[show abstract][hide abstract] ABSTRACT: An association between obesity and asthma has been documented previously, but the nature of this relationship remains unknown. This study aimed to determine if asthma is associated with a sedentary lifestyle which may explain this association. The energy expenditure (EE) on leisure activities was examined in 16,813 subjects, of at least 12 years of age, who participated in the Canadian National Population Health Survey 1994-95. Energy expenditure was calculated by multiplying the duration of leisure-time physical activity by its estimated metabolic energy cost. Asthma was considered to be present if an affirmative response was given to the question, 'Do you have asthma diagnosed by a health professional?' The average EE (+/- standard error) in males was 2.47 (+/- 0.11) kcal kg(-1) day(-1) for asthmatics and 1.98 (+/- 0.03) kcal kg(-1) day(-1) for non-asthmatics. The corresponding average EEs in females were 1.77 (+/- 0.08) and 1.54 (+/- 0.02) kcal kg(-1) day(-1) for asthmatics and non-asthmatics, respectively. The mean EE values decreased with increasing age. A significant interaction between asthma and age was noted with respect to EE; asthmatics tended to have higher mean EE values than non-asthmatics among younger subjects, and lower mean EE values in older subjects. This effect was more pronounced in females than in males. It was concluded that asthmatics were not consistently inactive compared with non-asthmatics. Leisure-time physical activity cannot explain the positive association between obesity and asthma.
Respiratory Medicine 02/2001; 95(1):13-8. · 2.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: The etiology of chronic obstructive pulmonary disease (COPD) has not been fully understood. This analysis assessed the prevalence of COPD and its risk factors among Canadian men and women. The analysis was based on the data from 7210 subjects aged 35 to 64 years who participated in the first cycle of National Population Health Survey in 1994-1995. COPD was considered present if an affirmative response was given to the question: "Do you have chronic bronchitis or emphysema diagnosed by a health professional?" In order to take the complex survey design into account, analytic weights incorporating a design effect were used in all statistical analyses. The prevalence of COPD was 2.1% in nonsmokers, 2.7% in ex-smokers, and 8.2% in smokers in women. In men, the corresponding prevalence was 0.8%, 2.9%, and 3.5%, respectively. The adjusted odds ratio for current smoking men and women who started smoking before age of 18 years was 3.0 and 5.9 compared with their nonsmoking counterparts. Overweight women demonstrated a 2.4-fold increase in the prevalence of COPD compared with women with normal weight. Men from low-income families had an odds ratio of 3.7 compared with those from high-income families. A history of allergy was significantly related to COPD in both men and women. COPD was common among Canadian women. Early initiation of smoking and being overweight had stronger relationships to the prevalence of COPD in women than in men. On the contrary, household income was more strongly related to COPD for men than for women.
Journal of Clinical Epidemiology 08/2000; 53(7):755-61. · 5.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: To assess smoking, obesity, and other risk factors for asthma, the authors examined 17,605 subjects aged 12 years or more who participated in the National Population Health Survey in 1994-1995. Asthma was considered present if an affirmative response was given to the question, "Do you have asthma diagnosed by a health professional?" The authors used analytic weights incorporating a design effect to take the complex survey design into account. The prevalence of asthma was 10.4% for males and 11.2% for females aged 12-24 years. Among the subjects aged 25 years or more, the prevalence varied from 4.1% to 5.8% for men and from 4.9% to 6.4% for women. Female smokers demonstrated a 1.7-fold increase in the prevalence of asthma compared with female nonsmokers, with the smoking effect more pronounced among female children and young adults. In contrast, there was no significant relation between smoking and asthma in males. The prevalence of asthma increased with increasing body mass index in females, but not in males. Immigrant status, history of allergy, and household income were significant predictors for both genders. Low household income was associated with a higher prevalence of asthma in men and women.
American Journal of Epidemiology 09/1999; 150(3):255-62. · 4.78 Impact Factor