Biomedical Data Science Seminar

“Weighted Cumulative Exposure (WCE) Modeling: Methods and Real-World Applications”

Presenter: Michal Abrahamowicz, PhD, Distinguished James McGill Professor, Department of Epidemiology and Biostatistics, McGill University. The presentation will take place via Zoom only. Please write to [email protected] to request the Zoom login details. Presentation SummaryWeighted Cumulative Exposure (WCE) methodology allows for flexible modeling of the cumulative effects of time-varying exposures (TVE). The method uses splines to estimate the weight function that quantifies how the relative importance of past exposures varies depending on how long ago they occurred. Originally developed for time-to-event (survival) analyses, WCE modeling has been extended to competing risks, marginal structural models and mixed effects linear modeling of longitudinal changes in a quantitative outcome. This talk will focus mostly on concepts and real-world applications. It will start with a brief overview of methodological challenges related to the assessment of the impact of TVEs, followed by the outline of the methodology: estimation, inference, and model selection. Next, some simulation results will be presented to assess WCE performance. The second half of the talk will illustrate the insights potentially offered by WCE analyses of a few real-world associations involving adverse effects of various medications and the impact of low-dose radiation on cancer incidence. BiographyDr. Michal Abrahamowicz is a Distinguished James McGill Professor of Biostatistics in the Department of Epidemiology & Biostatistics of the School of Population and Global Health of McGill University, in Montreal, Canada. He received PhD in Statistics in Krakow, Poland. In 1987, Dr. Abrahamowicz started a post-doctoral fellowship at McGill University, where he has been a faculty member since 1989. His research is supported by grants from the Canadian Institutes for Health Research (CIHR) and the Natural Sciences and Engineering Research Council (NSERC) of Canada. He develops new, flexible spline-based statistical methodology for survival analyses, with a focus on time-varying exposures and effects. Dr. Abrahamowicz also explores, and attempts to correct for, different biases in epidemiological studies. His collaborative research includes pharmaco-epidemiology, arthritis, cardiovascular and cancer epidemiology. Dr. Abrahamowicz is a co-founder and the co-chair of the international STRATOS initiative for improving the analyses of observational studies that involves >100 experts in statistics from 20 countries on 5 continents. In 2021, he was awarded an Honorary Lifetime Membership of the International Society for Clinical Biostatistics.

Sponsored by: Geisel School of Medicine