PubMed Health⌕ Search

Biomedical subjects

L S Mery

Publications and source records attributed to L S Mery.

6 recordsLinked to original sources
PubMed2001

Implausible birth weight for gestational age.

Various rules have been proposed to identify and exclude live births with implausible values of birth weight for gestational age from large perinatal data sets. The authors carried out a preliminary evaluation of common rules by examining the frequency and nature of rule-based exclusions among live births in Canada (excluding Ontario) between 1992 and 1994. There were 625 (0.09%), 133 (0.02%), 170 (0.02%), and 2,858 (0.40%) live births identified for exclusion by a median birth weight for gestational age +/-4 standard deviations (SD) rule, a +/-5 SD rule, a rule based on expert clinical opinion, and a modification of Tukey's rule, respectively. The birth weight and gestational age distribution of the exclusions depended on the particular rule used; for example, 12.1% and 0.3% of live births of > or =4,500 g were excluded under Tukey's rule and the rule based on expert opinion, respectively. Infant mortality rates among those excluded were 8-13 times higher than among all live births. Current rules for identifying implausible birth weight for gestational age tend to flag live births at high risk for infant death. Such rules may erroneously attenuate temporal trends in important perinatal outcomes.

Algorithms↗
PubMed2001

Oncogenic human papillomavirus infection and cervical lesions in aboriginal women of Nunavut, Canada.

BACKGROUND: The high rate of cervical cancer among aboriginal women of northern Canada has prompted the search for more aggressive methods to augment Papanicolaou (Pap) screening in this population. Nearly all cervical cancers result from oncogenic human papillomavirus (HPV) infections. This has generated interest for incorporating HPV testing into the current screening program. GOALS: To determine the prevalence of oncogenic HPVs in Nunavut, and to assess the association between HPV and squamous intraepithelial lesions (SIL). STUDY DESIGN: A cross-sectional study was conducted on the Pap-screened populations in 19 communities of Nunavut, Canada. Liquid-based cytology was used to screen for SIL. HPV testing was performed using the Hybrid Capture II assay. Correlates of HPV infection and SIL were assessed by logistic regression with control for potential confounders. RESULTS: In 1290 women ages 13 to 79 years, the prevalence rate was 26% for oncogenic HPV and 6.9% for SIL. The odds ratio for the association between HPV and SIL was 37.9 (95% CI, 17.7-80.8) after multivariate adjustment. This association increased markedly with increasing viral load. More than 90% of the women with squamous intraepithelial lesions had positive test results for HPV. More than 75% of the women who had positive test results for HPV but negative test results for SIL were younger than 30 years. CONCLUSION: The results of this study form the basis for further evaluation of the role that liquid-based cytology and HPV testing plays and will contribute to the strategy for cervical cancer prevention in Nunavut.

Adolescent↗
PubMed2001

An exploratory analysis of the effect of pesticide exposure on the risk of spontaneous abortion in an Ontario farm population.

The toxicity of pesticides on human reproduction is largely unknown--particularly how mixtures of pesticide products might affect fetal toxicity. The Ontario Farm Family Health Study collected data by questionnaire on the identity and timing of pesticide use on the farm, lifestyle factors, and a complete reproductive history from the farm operator and eligible couples living on the farm. A total of 2,110 women provided information on 3,936 pregnancies, including 395 spontaneous abortions. To explore critical windows of exposure and target sites for toxicity, we examined exposures separately for preconception (3 months before and up to month of conception) and postconception (first trimester) windows and for early (< 12 weeks) and late (12-19 weeks) spontaneous abortions. We observed moderate increases in risk of early abortions for preconception exposures to phenoxy acetic acid herbicides [odds ratio (OR) = 1.5; 95% confidence interval (CI), 1.1-2.1], triazines (OR = 1.4; 95% CI, 1.0-2.0), and any herbicide (OR = 1.4; 95% CI, 1.1-1.9). For late abortions, preconception exposure to glyphosate (OR = 1.7; 95% CI, 1.0-2.9), thiocarbamates (OR = 1.8; 95% CI, 1.1-3.0), and the miscellaneous class of pesticides (OR = 1.5; 95% CI, 1.0-2.4) was associated with elevated risks. Postconception exposures were generally associated with late spontaneous abortions. Older maternal age (> 34 years of age) was the strongest risk factor for spontaneous abortions, and we observed several interactions between pesticides in the older age group using Classification and Regression Tree analysis. This study shows that timing of exposure and restricting analyses to more homogeneous endpoints are important in characterizing the reproductive toxicity of pesticides.

Abortion, Spontaneous↗
PubMed2000

Clues to the aetiological heterogeneity of testicular seminomas and non-seminomas: time trends and age-period-cohort effects.

BACKGROUND: Most previous epidemiological studies have treated testicular cancer as a single entity. However, some investigators suggest that testicular seminomas and non-seminomas may have different risk profiles. We examine the time trends in incidence of the two main histological types separately. METHODS: From 1970 through 1995, 7296 cases of testicular cancer were registered in the Canadian provinces of Ontario, Saskatchewan and British Columbia. In addition to analyses of the secular trends by age group and birth cohort, an age-period-cohort (APC) model with standard Poisson assumptions was fitted to the data to assess the time effects. RESULTS: The age-adjusted incidence rate for seminomas increased by 53%, from 1.5 per 100 000 males in 1970-1971 to 2.3 per 100 000 males in 1994-1995. Non-seminomas increased by 91%, from 1.1 to 2.1 per 100 000 males over the same period. Non-seminomas were more frequent at young ages whereas seminomas dominated in older ages. In contrast to seminomas, non-seminomas occurred predominantly among adolescent men (15-19 years), with a fourfold increase between 1970-1971 and 1994-1995. Age-period-cohort modelling showed that the increase in the risk of both seminomas and non-seminomas followed a birth cohort pattern, but with differences in birth cohorts in addition to significantly distinct age patterns. CONCLUSIONS: Our findings support the hypothesis postulating aetiological heterogeneity in the development of seminomas and non-seminomas. We suggest that epidemiological studies of testicular cancer treat seminomas and non-seminomas separately.

Adolescent↗
PubMed1999

Exposure to phenoxy herbicides and the risk of spontaneous abortion.

The Ontario Farm Family Health Study was designed to assess retrospectively the potential adverse effects of exposure to pesticides on pregnancy. Information on the health and life style of approximately 2,000 farm couples, as well as a history of use of pesticides on the farm, was collected by questionnaire. This analysis focuses on pre- and postconception exposure to phenoxy herbicides and the risk of spontaneous abortion using the complete (to date) pregnancy history for each woman. Preconception exposure (from 3 months before conception to the month of conception) was weakly associated with the risk of spontaneous abortion at <20 weeks' gestation [adjusted odds ratio (OR) = 1.1; 95% confidence interval (CI) = 0.6-1.9]. When the analyses were restricted to spontaneous abortions of <12 weeks, the risk was more than doubled (adjusted OR = 2.5; 95% CI = 1.0-6.4), but the results were sensitive to the cutpoint used. If the husband did not normally wear protective equipment during application, the crude OR for early spontaneous abortions was 5.0 (95% CI = 0.7-36.2). Exposure to phenoxy herbicides during the first trimester was generally not associated with increased risk of spontaneous abortion. The results suggest a possible role of preconception (possibly paternal) exposures to phenoxy herbicides in the risk of early spontaneous abortions.

Abortion, Spontaneous↗