Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2012
Inconsistent study findings of exercise on areal bone density highlight the need to include param... more Inconsistent study findings of exercise on areal bone density highlight the need to include parameters of bone geometry and volumetric bone density measurements. Using a systematic review and meta-analysis, we found a decrease in bone loss through the maintenance of cortical and trabecular volumetric bone mineral density (BMD). Studies with longer exercise durations and larger sample sizes are needed. Exercise has long been recommended to prevent age-related loss of bone mass in postmenopausal women. However, inconsistent study findings on the effect of exercise on BMD preservation have highlighted the importance of extending the evaluation of bone to include the parameters of bone geometry. We conducted both a systematic review and meta-analysis of the effects of exercise on bone geometry and volumetric BMD in postmenopausal women. We searched MEDLINE, PubMed, and EMBASE from 1950 to April 2009 and included prospective, randomized controlled trials of healthy postmenopausal women w...
With the explosion of microarray studies, an enormous amount of data is being produced. Systemati... more With the explosion of microarray studies, an enormous amount of data is being produced. Systematic integration of gene expression data from different sources increases statistical power of detecting differentially expressed genes and allows assessment of heterogeneity. The challenge, however, is in designing and implementing efficient analytic methodologies for combination of data generated by different research groups. We extended traditional effect size models to combine information from different microarray datasets by incorporating a quality measure for each gene in each study into the effect size estimation. We illustrated our method by integrating two datasets generated using different Affymetrix oligonucleotide types. Our results indicate that the proposed quality-adjusted weighting strategy for modelling inter-study variation of gene expression profiles not only increases consistency and decreases heterogeneous results between these two datasets, but also identifies many mor...
Journal of obstetrics and gynaecology Canada : JOGC = Journal d'obstétrique et gynécologie du Canada : JOGC, 2005
To determine whether the incidence of adverse obstetric outcomes is higher in singleton pregnanci... more To determine whether the incidence of adverse obstetric outcomes is higher in singleton pregnancies achieved by in vitro fertilization (IVF) than in spontaneously conceived singletons matched for maternal age. We used comprehensive search strategies to search MEDLINE and EMBASE databases. We selected case-control and cohort studies that compared singleton pregnancies conceived by IVF or intracytoplasmic sperm injection (ICSI) with spontaneously conceived singletons (matched for maternal age [case-control studies] or controlled for maternal age [cohort studies]). Two reviewers independently assessed titles, abstracts, and study quality and extracted data. Statistical analysis was performed with Review Manager for Windows (Version 4.2, Oxford, UK). We performed meta-analysis of dichotomous data, using odds ratios (ORs) as measures of effect size, with a random effects model. We followed the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines for meta-analysis of ...
Lipid abnormalities in patients with systemic lupus erythematosus (SLE) are common and likely are... more Lipid abnormalities in patients with systemic lupus erythematosus (SLE) are common and likely are one of the causes of premature atherosclerosis in these patients. Our aims were to determine the frequency and pattern of dyslipoproteinemia at presentation of pediatric SLE; and to determine the association between dyslipoproteinemia and markers of disease activity and inflammatory markers at presentation of pediatric SLE. Serum lipid measurements were obtained at diagnosis before corticosteroid treatment for an inception cohort of 54 patients. Total cholesterol, triglyceride, LDL-C, and HDL-C levels were regressed on measures of inflammation, disease activity, and disease symptoms. At least one lipid abnormality was present in the majority of patients (63%), an elevated triglyceride level being the most common lipid abnormality (62%). Triglycerides were best predicted by fibrinogen, nephritis, and pleuritis (model R2 = 0.6). Albumin, C4, and white blood cell count were found to predic...
In this qualitative descriptive study, we explored health care professionals' perceptions of ... more In this qualitative descriptive study, we explored health care professionals' perceptions of the influence of context (i.e., organizational culture, structure, resources, capabilities/competencies, and politics) on evidence-based pain practices. A total of 16 focus groups with 147 health care professionals were conducted in three neonatal intensive care units (NICUs) in central and eastern Canada. Three overarching themes emerged from the data, which captured influences on optimal pain practices in the NICU, including (a) a culture of collaboration and support for evidence-based practice, (b) threats to autonomous decision making, and (c) complexities in care delivery. These results were consistent with theoretical conceptualizations of how context influences practice, as well as recent empirical research findings. This study supports the importance of context in shaping evidence-based practices by health care professionals in the management of pain in the NICU.
Journal of obstetrics and gynaecology Canada : JOGC = Journal d'obstétrique et gynécologie du Canada : JOGC, 2013
Excess weight gain during pregnancy is associated with increased risks of overweight and obesity ... more Excess weight gain during pregnancy is associated with increased risks of overweight and obesity in both women and their children. Conversely, inadequate weight gain can predispose to growth restriction, which is also associated with childhood obesity. Because most pregnant women now gain more weight than is recommended in guidelines and a substantial portion gain less than the recommended amounts, we sought to determine factors associated with inappropriate weight gain, including physical, lifestyle, knowledge, and particularly psychological factors. We conducted a self-administered cross-sectional survey of English-speaking women with a live, singleton gestation. Biologically relevant variables significant at P < 0.10 were included in multiple logistic regression. Three hundred thirty women completed the survey, a response rate of 90.7%. Gaining weight above the amount recommended in guidelines was associated with planning to do so (adjusted OR [aOR] 11.18; 95% CI 4.45 to 28.06...
Hemophilia A is a rare, sex-linked genetic disorder treated with intravenous administration of fa... more Hemophilia A is a rare, sex-linked genetic disorder treated with intravenous administration of factor VIII (FVIII) to prevent bleeding; however, approaches vary across and within countries. Value-of-information (VOI) methods identify situations in which the cost-benefit evidence is sufficient to adopt one treatment strategy over another; when the evidence is insufficient, VOI methods provide the optimal sample size for additional research. The objective of the study was to use VOI methods in a cost-benefit decision context to evaluate the current evidence in support of using (1) alternate day prophylaxis (AP), (2) tailored prophylaxis (TP) or (3) on-demand treatment (OD) with FVIII to prevent arthropathy in children with severe hemophilia A. To apply VOI methods, several parameters such as incidence, time horizon for the decision, costs, and threshold values to avoid MRI-detected joint damage or arthropathy were defined. Two baseline threshold values of willingness to pay for avoidi...
Genetic variants that predispose adults and the elderly to high blood pressure are largely unknow... more Genetic variants that predispose adults and the elderly to high blood pressure are largely unknown. We used a bivariate linear mixed model approach to jointly test the associations of common single-nucleotide polymorphisms with systolic and diastolic blood pressure using data from a genome-wide association study consisting of genetic variants from chromosomes 3 and 9 and longitudinal measured phenotypes and environment variables from unrelated individuals of Mexican American ethnicity provided by the Genetic Analysis Workshop 18. Despite the small sample size of a maximum of 131 unrelated subjects, a few single-nucleotide polymorphisms appeared significant at the genome-wide level. Simulated data, which was also provided by Genetic Analysis Workshop 18 organizers, showed higher power of the bivariate approach over univariate analysis to detect the association of a selected single-nucleotide polymorphism with modest effect. This suggests that the bivariate approach to longitudinal da...
Many complex diseases are related to genetics, and it is of great interest to evaluate the associ... more Many complex diseases are related to genetics, and it is of great interest to evaluate the association between single-nucleotide polymorphisms (SNPs) and disease outcome. The association of genetics with outcome can be modified by covariates such as age, sex, smoking status, and membership to the same pedigree. In this paper, we propose a block entropy method to separate two classes of SNPs, for which the association with hypertension is either sensitive or insensitive to the covariates. We also propose a consistency entropy method to further reduce the number of SNPs that might be associated with the outcome. Based on the data provided by the organizers of Genetic Analysis Workshop 18, we calculated the block entropies for six different blocking strategies. Using block entropy and consistency entropy, we identified 230 SNPs on chromosome 9 that are most likely to be associated with the outcome and whose associations with hypertension are sensitive to the covariates.
Randomised controlled trials (RCTs) are often considered as the gold standard for assessing new h... more Randomised controlled trials (RCTs) are often considered as the gold standard for assessing new health interventions. Patients are randomly assigned to receive an intervention or control. The effect of the intervention can be estimated by comparing outcomes between groups, whose prognostic factors are expected to balance by randomisation. However, patients' non-compliance with their assigned treatment will undermine randomisation and potentially bias the estimate of treatment effect. Through simulation, we aim to compare common approaches in analysing non-compliant data under different non-compliant scenarios. Based on a real study, we simulated hypothetical trials by varying three non-compliant factors: the type, randomness and degree of non-compliance. We compared the intention-to-treat (ITT), as-treated (AT), per-protocol (PP), instrumental variable (IV) and complier average casual effect (CACE) analyses to estimate large (50% improvement over the control), moderate (25% impr...
Glycemic index (GI) and glycemic load (GL) have been associated with coronary heart disease (CHD)... more Glycemic index (GI) and glycemic load (GL) have been associated with coronary heart disease (CHD) risk in some but not all cohort studies. We therefore assessed the association of GI and GL with CHD risk in prospective cohorts. We searched MEDLINE, EMBASE, and CINAHL (through April 5, 2012) and identified all prospective cohorts assessing associations of GI and GL with incidence of CHD. Meta-analysis of observational studies in epidemiology (MOOSE) methodologies were used. Relative measures of risk, comparing the group with the highest exposure (mean GI of cohorts=84.4 GI units, range 79.9 to 91; mean GL of cohorts=224.8, range 166 to 270) to the reference group (mean GI=72.3 GI units, range 68.1 to 77; mean GL=135.4, range 83 to 176), were pooled using random-effects models, expressed as relative risk (RR) with heterogeneity assessed by χ(2) and quantified by I(2). Subgroups included sex and duration of follow-up. Ten studies (n=240 936) were eligible. Pooled analyses showed an inc...
Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2012
Inconsistent study findings of exercise on areal bone density highlight the need to include param... more Inconsistent study findings of exercise on areal bone density highlight the need to include parameters of bone geometry and volumetric bone density measurements. Using a systematic review and meta-analysis, we found a decrease in bone loss through the maintenance of cortical and trabecular volumetric bone mineral density (BMD). Studies with longer exercise durations and larger sample sizes are needed. Exercise has long been recommended to prevent age-related loss of bone mass in postmenopausal women. However, inconsistent study findings on the effect of exercise on BMD preservation have highlighted the importance of extending the evaluation of bone to include the parameters of bone geometry. We conducted both a systematic review and meta-analysis of the effects of exercise on bone geometry and volumetric BMD in postmenopausal women. We searched MEDLINE, PubMed, and EMBASE from 1950 to April 2009 and included prospective, randomized controlled trials of healthy postmenopausal women w...
With the explosion of microarray studies, an enormous amount of data is being produced. Systemati... more With the explosion of microarray studies, an enormous amount of data is being produced. Systematic integration of gene expression data from different sources increases statistical power of detecting differentially expressed genes and allows assessment of heterogeneity. The challenge, however, is in designing and implementing efficient analytic methodologies for combination of data generated by different research groups. We extended traditional effect size models to combine information from different microarray datasets by incorporating a quality measure for each gene in each study into the effect size estimation. We illustrated our method by integrating two datasets generated using different Affymetrix oligonucleotide types. Our results indicate that the proposed quality-adjusted weighting strategy for modelling inter-study variation of gene expression profiles not only increases consistency and decreases heterogeneous results between these two datasets, but also identifies many mor...
Journal of obstetrics and gynaecology Canada : JOGC = Journal d'obstétrique et gynécologie du Canada : JOGC, 2005
To determine whether the incidence of adverse obstetric outcomes is higher in singleton pregnanci... more To determine whether the incidence of adverse obstetric outcomes is higher in singleton pregnancies achieved by in vitro fertilization (IVF) than in spontaneously conceived singletons matched for maternal age. We used comprehensive search strategies to search MEDLINE and EMBASE databases. We selected case-control and cohort studies that compared singleton pregnancies conceived by IVF or intracytoplasmic sperm injection (ICSI) with spontaneously conceived singletons (matched for maternal age [case-control studies] or controlled for maternal age [cohort studies]). Two reviewers independently assessed titles, abstracts, and study quality and extracted data. Statistical analysis was performed with Review Manager for Windows (Version 4.2, Oxford, UK). We performed meta-analysis of dichotomous data, using odds ratios (ORs) as measures of effect size, with a random effects model. We followed the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines for meta-analysis of ...
Lipid abnormalities in patients with systemic lupus erythematosus (SLE) are common and likely are... more Lipid abnormalities in patients with systemic lupus erythematosus (SLE) are common and likely are one of the causes of premature atherosclerosis in these patients. Our aims were to determine the frequency and pattern of dyslipoproteinemia at presentation of pediatric SLE; and to determine the association between dyslipoproteinemia and markers of disease activity and inflammatory markers at presentation of pediatric SLE. Serum lipid measurements were obtained at diagnosis before corticosteroid treatment for an inception cohort of 54 patients. Total cholesterol, triglyceride, LDL-C, and HDL-C levels were regressed on measures of inflammation, disease activity, and disease symptoms. At least one lipid abnormality was present in the majority of patients (63%), an elevated triglyceride level being the most common lipid abnormality (62%). Triglycerides were best predicted by fibrinogen, nephritis, and pleuritis (model R2 = 0.6). Albumin, C4, and white blood cell count were found to predic...
In this qualitative descriptive study, we explored health care professionals' perceptions of ... more In this qualitative descriptive study, we explored health care professionals' perceptions of the influence of context (i.e., organizational culture, structure, resources, capabilities/competencies, and politics) on evidence-based pain practices. A total of 16 focus groups with 147 health care professionals were conducted in three neonatal intensive care units (NICUs) in central and eastern Canada. Three overarching themes emerged from the data, which captured influences on optimal pain practices in the NICU, including (a) a culture of collaboration and support for evidence-based practice, (b) threats to autonomous decision making, and (c) complexities in care delivery. These results were consistent with theoretical conceptualizations of how context influences practice, as well as recent empirical research findings. This study supports the importance of context in shaping evidence-based practices by health care professionals in the management of pain in the NICU.
Journal of obstetrics and gynaecology Canada : JOGC = Journal d'obstétrique et gynécologie du Canada : JOGC, 2013
Excess weight gain during pregnancy is associated with increased risks of overweight and obesity ... more Excess weight gain during pregnancy is associated with increased risks of overweight and obesity in both women and their children. Conversely, inadequate weight gain can predispose to growth restriction, which is also associated with childhood obesity. Because most pregnant women now gain more weight than is recommended in guidelines and a substantial portion gain less than the recommended amounts, we sought to determine factors associated with inappropriate weight gain, including physical, lifestyle, knowledge, and particularly psychological factors. We conducted a self-administered cross-sectional survey of English-speaking women with a live, singleton gestation. Biologically relevant variables significant at P < 0.10 were included in multiple logistic regression. Three hundred thirty women completed the survey, a response rate of 90.7%. Gaining weight above the amount recommended in guidelines was associated with planning to do so (adjusted OR [aOR] 11.18; 95% CI 4.45 to 28.06...
Hemophilia A is a rare, sex-linked genetic disorder treated with intravenous administration of fa... more Hemophilia A is a rare, sex-linked genetic disorder treated with intravenous administration of factor VIII (FVIII) to prevent bleeding; however, approaches vary across and within countries. Value-of-information (VOI) methods identify situations in which the cost-benefit evidence is sufficient to adopt one treatment strategy over another; when the evidence is insufficient, VOI methods provide the optimal sample size for additional research. The objective of the study was to use VOI methods in a cost-benefit decision context to evaluate the current evidence in support of using (1) alternate day prophylaxis (AP), (2) tailored prophylaxis (TP) or (3) on-demand treatment (OD) with FVIII to prevent arthropathy in children with severe hemophilia A. To apply VOI methods, several parameters such as incidence, time horizon for the decision, costs, and threshold values to avoid MRI-detected joint damage or arthropathy were defined. Two baseline threshold values of willingness to pay for avoidi...
Genetic variants that predispose adults and the elderly to high blood pressure are largely unknow... more Genetic variants that predispose adults and the elderly to high blood pressure are largely unknown. We used a bivariate linear mixed model approach to jointly test the associations of common single-nucleotide polymorphisms with systolic and diastolic blood pressure using data from a genome-wide association study consisting of genetic variants from chromosomes 3 and 9 and longitudinal measured phenotypes and environment variables from unrelated individuals of Mexican American ethnicity provided by the Genetic Analysis Workshop 18. Despite the small sample size of a maximum of 131 unrelated subjects, a few single-nucleotide polymorphisms appeared significant at the genome-wide level. Simulated data, which was also provided by Genetic Analysis Workshop 18 organizers, showed higher power of the bivariate approach over univariate analysis to detect the association of a selected single-nucleotide polymorphism with modest effect. This suggests that the bivariate approach to longitudinal da...
Many complex diseases are related to genetics, and it is of great interest to evaluate the associ... more Many complex diseases are related to genetics, and it is of great interest to evaluate the association between single-nucleotide polymorphisms (SNPs) and disease outcome. The association of genetics with outcome can be modified by covariates such as age, sex, smoking status, and membership to the same pedigree. In this paper, we propose a block entropy method to separate two classes of SNPs, for which the association with hypertension is either sensitive or insensitive to the covariates. We also propose a consistency entropy method to further reduce the number of SNPs that might be associated with the outcome. Based on the data provided by the organizers of Genetic Analysis Workshop 18, we calculated the block entropies for six different blocking strategies. Using block entropy and consistency entropy, we identified 230 SNPs on chromosome 9 that are most likely to be associated with the outcome and whose associations with hypertension are sensitive to the covariates.
Randomised controlled trials (RCTs) are often considered as the gold standard for assessing new h... more Randomised controlled trials (RCTs) are often considered as the gold standard for assessing new health interventions. Patients are randomly assigned to receive an intervention or control. The effect of the intervention can be estimated by comparing outcomes between groups, whose prognostic factors are expected to balance by randomisation. However, patients' non-compliance with their assigned treatment will undermine randomisation and potentially bias the estimate of treatment effect. Through simulation, we aim to compare common approaches in analysing non-compliant data under different non-compliant scenarios. Based on a real study, we simulated hypothetical trials by varying three non-compliant factors: the type, randomness and degree of non-compliance. We compared the intention-to-treat (ITT), as-treated (AT), per-protocol (PP), instrumental variable (IV) and complier average casual effect (CACE) analyses to estimate large (50% improvement over the control), moderate (25% impr...
Glycemic index (GI) and glycemic load (GL) have been associated with coronary heart disease (CHD)... more Glycemic index (GI) and glycemic load (GL) have been associated with coronary heart disease (CHD) risk in some but not all cohort studies. We therefore assessed the association of GI and GL with CHD risk in prospective cohorts. We searched MEDLINE, EMBASE, and CINAHL (through April 5, 2012) and identified all prospective cohorts assessing associations of GI and GL with incidence of CHD. Meta-analysis of observational studies in epidemiology (MOOSE) methodologies were used. Relative measures of risk, comparing the group with the highest exposure (mean GI of cohorts=84.4 GI units, range 79.9 to 91; mean GL of cohorts=224.8, range 166 to 270) to the reference group (mean GI=72.3 GI units, range 68.1 to 77; mean GL=135.4, range 83 to 176), were pooled using random-effects models, expressed as relative risk (RR) with heterogeneity assessed by χ(2) and quantified by I(2). Subgroups included sex and duration of follow-up. Ten studies (n=240 936) were eligible. Pooled analyses showed an inc...
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Papers by J. Beyene