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DTSTAMP:20251223T041658Z
DESCRIPTION:Michal Abrahamowicz\, PhD\n\nDistinguished James 91ºÚÁÏÍø Profess
 or\n	Department of Epidemiology\, Biostatistics and Occupational Health | M
 cGill University\n\nWHEN: Wednesday\, January 7\, 2026\, from 3:30 to 4:30
  p.m.\n	WHERE: Hybrid | 2001 91ºÚÁÏÍø College Avenue\, Rm 1140\; Zoom\n	NOTE: 
 Michal Abrahamowicz will be presenting in-person at SPGH \n\nAbstract\n\nW
 eighted Cumulative Exposure (WCE) methodology has been developed to allow 
 for flexible modelling of the cumulative effects of time-varying exposures
  (TVE) [1]. In time-to-event analyses\, the joint impact of past TVE value
 s\, for person i\, is quantified as: WCE�� (�) = ∑� � �(�−�)[���� (�)]\, w
 here u is the current time when the hazard is assessed\, and ��� (�)\, � ≤
  �\, represent TVE values observed at earlier times. The essential compone
 nt of the model is the weight function � �(�−�) which is estimated using c
 ubic splines and indicates how the importance of the TVE value observed at
  time t\, for the hazard at time� �(�−�)\, varies with time �(�−�) since i
 t was measured [1]. The WCE modeling\, originally developed for Cox propor
 tional hazards analyses [1]\, has been extended to competing risks\, margi
 nal structural models and mixed effects linear modeling of longitudinal ch
 anges in a quantitative outcome (see e.g. a recent overview in [2]). It ha
 s been recognized as one of the most useful methods for assessing TVE effe
 cts in pharmaco-epidemiology [3].\n	\n	The talk will present an overview of 
 the phases of the development and establishing of the WCE methodology\, in
 cluding its consecutive extensions\, and validation in simulations. I will
  discuss how and to what extent our work on the WCE modelling followed the
  phases identified by Heinze et al in their recent paper on the phases of 
 methodological research in biostatistics [4]. In addition\, further phases
  such as (a) establishing the need for the new methodological development\
 , (b) proof-of-the-concept phase\, and (c) refining the estimation and sta
 tistical inference\, will be outlined.\n\nIn this context\, three importan
 t aspects of real-world applications will be briefly discussed. (i) Firstl
 y\, I will emphasize the need to incorporate substantive knowledge\, and t
 he related challenges. (ii) Secondly\, I will illustrate the ability of th
 e WCE analyses to provide new insights into\, and generate new hypotheses 
 about\, the underlying biological processes linking the exposure with the 
 outcomes. (iii) I will also outline how some real-world results stimulated
  new methodological developments\, necessary to address additional analyti
 cal challenges.\n\nFinally\, the need of future research to carry out the 
 additional phase\, focusing on neutral simulations to further validate the
  WCE methodology and compare it with the existing alternative approaches\,
  as recommended in [4]\, will be briefly presented\,\n\n[1] Sylvestre M-P 
 & Abrahamowicz M. Flexible modeling of the cumulative effects of\n	time dep
 endent exposures on the hazard. Statistics in Medicine. 2009 Nov\;28(27):3
 437-3453.\n	[2] Abrahamowicz M. Assessing cumulative effects of medication 
 use: new insights\n	and new challenges. Invited Commentary. Pharmacoepidemi
 ology & Drug Safety.\n	2024 Jan\;33(1):e5746. doi: 10.1002/pds.5746.\n	[3] P
 azzagli L\, Linder M\, et al. Methods for time-varying exposure related pr
 oblems in\n	pharmacoepidemiology: An overview. Pharmacoepidemiology & Drug 
 Safety 2018\;27:148-160.\n	[4] Heinze G.\, Boulesteix AL\, Kammer M.\, Morr
 is TP\, White I. Phases of methodological research in biostatistics. Biome
 trical Journal. 2024.\n\nSpeaker Bio\n\nMichal Abrahamowicz is a Distingui
 shed James 91ºÚÁÏÍø Professor of Biostatistics at 91ºÚÁÏÍø. He deve
 lops new\, flexible statistical methodology for survival analyses\, with f
 ocus on time-varying exposures and effects. He also explores\, and attempt
 s to correct for\, different biases in epidemiological studies and promote
 s creative applications of statistical simulations. He is a co-founder and
  the co-chair of the international STRATOS initiative for improving the an
 alyses of observational studies. He is a Honorary Lifetime member of the I
 nternational Society for Clinical Biostatistics.\n
DTSTART:20260107T203000Z
DTEND:20260107T213000Z
SUMMARY:Phases of Development of the Weighted Cumulative Exposure Modeling
URL:/epi-biostat-occh/channels/event/phases-developmen
 t-weighted-cumulative-exposure-modeling-369614
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