A5048550846- Advanced Causal Inference Techniques
- Statistical Methods and Inference
- Statistical Methods in Clinical Trials
- Statistical Methods and Bayesian Inference
- HIV/AIDS Research and Interventions
- Hepatitis C virus research
- Health Systems, Economic Evaluations, Quality of Life
- HIV, Drug Use, Sexual Risk
- Liver Disease Diagnosis and Treatment
- Food Security and Health in Diverse Populations
- HIV-related health complications and treatments
- Homelessness and Social Issues
- HIV Research and Treatment
- HIV/AIDS drug development and treatment
- Child Nutrition and Water Access
- Genetic Associations and Epidemiology
- Hepatitis B Virus Studies
- Obesity, Physical Activity, Diet
- COVID-19 epidemiological studies
- Machine Learning in Healthcare
- Mental Health Research Topics
- Healthcare Policy and Management
- Health disparities and outcomes
- Optimal Experimental Design Methods
- LGBTQ Health, Identity, and Policy
McGill University
2016-2025
University of Washington
2004-2023
Kaiser Permanente Washington Health Research Institute
2020-2023
University at Albany, State University of New York
2023
Centre Hospitalier de l’Université de Montréal
2021-2022
Jewish General Hospital
2022
University of British Columbia
2021
AIDS Vancouver
2021
University of Victoria
2021
Community Based Research Centre
2021
Purpose Studies of the real-world comparative effectiveness drugs conducted using computerized healthcare databases typically involve an incident new-user cohort design for head-to-head comparisons between two medications, exclusively treatment-naïve patients. However, desired contrast often involves one new drug compared with older drug, which many users may have switched from, seriously restricting scope studies. Methods We introduce prevalent designs effect studies, where are scarce....
Summary A dynamic regime is a function that takes treatment and covariate history baseline covariates as inputs returns decision to be made. Murphy (2003, Journal of the Royal Statistical Society, Series B 65, 331–366) Robins (2004, Proceedings Second Seattle Symposium on Biostatistics , 189–326) have proposed models developed semiparametric methods for making inference about optimal in multi‐interval trial provide clear advantages over traditional parametric approaches. We show Murphy's...
Chronic malnutrition, termed stunting, is defined as suboptimal linear growth, affects one third of children in developing countries, and leads to increased mortality poor developmental outcomes. The causes childhood stunting are unknown, strategies improve growth related outcomes have only had modest impacts. Recent studies shown that the ecosystem microbes human gut, microbiota, can induce changes weight. However, specific gut microbiota contribute remain no investigated a determinant...
Inverse probability-weighted marginal structural models with binary exposures are common in epidemiology. Constructing inverse probability weights for a continuous exposure can be complicated by the presence of outliers, and need to identify parametric form account nonconstant variance. We explored performance various methods construct using Monte Carlo simulation. generated two outcomes data sampled from large empirical cohort. The first followed normal distribution homoscedastic second...
Social epidemiologists often seek to determine the mechanisms that underlie health disparities. This work is typically based on mediation procedures may not be justified with exposures of common interest in social epidemiology. In this analysis, we explored consequences using standard approaches, referred as difference and generalized product methods, when mediator-outcome confounders are associated exposure. We compared these inverse probability-weighted marginal structural models,...
Abstract Background. Human immunodeficiency virus (HIV)–infected patients coinfected with hepatitis B (HBV) and C (HCV) viruses are at increased risk of end-stage liver disease (ESLD). Whether modern antiretroviral therapy has reduced ESLD is unknown. Methods. Twelve clinical cohorts in the United States Canada participating North American AIDS Cohort Collaboration on Research Design validated events from 1996 to 2010. incidence rates rate ratios according status adjusted for age, sex, race,...
<h3>Background:</h3> In Canada, gay, bisexual and other men who have sex with (GBM) are disproportionately affected by HIV. Our objective was to describe access HIV pre-exposure prophylaxis (PrEP) identify factors associated not using PrEP among self-reported HIV-negative or HIV-unknown GBM. <h3>Methods:</h3> This a cross-sectional analysis of the Engage study cohort. Between 2017 2019, sexually active GBM aged 16 years more in Montréal, Toronto Vancouver were recruited via respondent-driven...
North American and European health agencies recently warned of severe breathing problems associated with gabapentinoids, including in patients chronic obstructive pulmonary disease (COPD), although supporting evidence is limited.
ABSTRACT Background Self‐directed interventions are cost‐effective for patients with cancer and their family caregivers, but barriers to use can compromise adherence efficacy. Aim Pilot a Sequential Multiple Assignment Randomized Trial (SMART) develop time‐varying dyadic self‐management intervention that follows stepped‐care approach in providing different types of guidance optimize the delivery Coping‐Together, self‐directed intervention. Methods 48 caregivers were randomized Stage 1 to:...
BackgroundAlthough interferon-gamma release assays (IGRA) are promising alternatives to the tuberculin skin test, interpretation of repeated testing results is hampered by lack evidence on optimal cut-offs for conversions and reversions. A logical start determine within-person variability T-cell responses during serial testing.Methodology/Principal FindingsWe performed a pilot study in India, evaluate short-term reproducibility QuantiFERON-TB Gold In Tube assay (QFT) among 14 healthcare...
Summary Personalized medicine is a rapidly expanding area of health research wherein patient level information used to inform their treatment. Dynamic treatment regimens (DTRs) are means formalizing the sequence decisions that characterize personalized management plans. Identifying DTR which optimizes expected outcome obvious interest and numerous methods have been proposed for this purpose. We present new approach builds on two established methods: Q‐learning G‐estimation, offering doubly...
Infants who receive prolonged and exclusive breastfeeding grow more slowly during the first year of life than those do not. However, infant feeding growth are dynamic processes in which may affect growth, prior size also influence subsequent decisions. The authors carried out an observational analysis 17,046 Belarusian infants were recruited between June 1996 December 1997 participated a cluster-randomized trial promotion intervention. To assess effects on feeding, restricted to breastfed...
Abstract The area of dynamic treatment regimes (DTR) aims to make inference about adaptive, multistage decision‐making in clinical practice. A DTR is a set decision rules, one per interval treatment, where each function and covariate history that returns recommended treatment. Q‐learning popular method from the reinforcement learning literature has recently been applied estimate DTRs. While, principle, can be used for both randomized observational data, focus thus far exclusively on setting....
Marginal structural Cox Models (Cox MSMs) have been used to estimate the causal effect of a time-varying treatment on hazard when there exist time-dependent confounders, which are themselves also affected by previous treatment.A MSM can be estimated via inverse-probability-of-treatment weighting (IPTW) estimator.However, IPTW estimators suffer from large variability if some observations assigned extremely high weights.Weight truncation has proposed as one simple solution this problem, but...
Patients with HIV exposed to the antiretroviral drug abacavir may have an increased risk of cardiovascular disease (CVD). There is concern that this association arises because a channeling bias. Even if exposure risk, it not clear how changes as cumulates.We assess effect on CVD events in Swiss Cohort Study. We use new marginal structural Cox model estimate flexible function past exposures while accounting for factors potentially lie causal pathway between and CVD.A total 11,856 patients...
Although review papers on causal inference methods are now available, there is a lack of introductory overviews what they can render and the guiding criteria for choosing one particular method. This tutorial gives an overview in situations where exposure interest set at chosen baseline (“point exposure”) target outcome arises later time point. We first phrase relevant questions make case being specific about possible levels involved populations which question relevant. Using potential...
Marginal structural models (MSM) provide a powerful tool to control for confounding by time-dependent covariate without inappropriately adjusting its role as variable affected treatment (Hernán et al., 2000). In this paper, we demonstrate that it is possible fit marginal Cox model directly, rather than the typical approach of using pooled logistic regression, weighted proportional hazards function has been implemented in standard software. To evaluate performance directly via inverse...
Marijuana smoking is common and believed to relieve many symptoms, but daily use has been associated with liver fibrosis in cross-sectional studies. We aimed estimate the effect of marijuana on disease progression a Canadian prospective multicenter cohort human immunodeficiency virus/hepatitis C virus (HIV/HCV) coinfected persons.Data were analyzed for 690 HCV polymerase chain reaction positive (PCR-positive) individuals without significant or end-stage (ESLD) at baseline. Time-updated Cox...
Abstract Background Direct acting antivirals ( DAA s) have revolutionized hepatitis C HCV ) treatment with >90% cure rates even in real‐world studies, giving hope that can be eliminated. However, for s to a population‐level impact on the burden of disease, uptake needs expanded. We investigated temporal trends and evaluated factors associated second‐generation initiation efficacy among key HIV ‐ co‐infected populations Canada. Methods The Canadian Co‐Infection Cohort Study prospectively...
<h3>Background:</h3> Limited evidence on the costs of homelessness in Canada is available. We estimated average annual costs, total and by cost category, that homeless people with mental illness engender from perspective society. also identified individual characteristics associated higher costs. <h3>Methods:</h3> As part At Home/Chez Soi trial Housing First for illness, 990 participants were assigned to usual-treatment (control) group 5 Canadian cities (Vancouver, Winnipeg, Toronto,...