Bayesian statistician and independent consultant — based in London — Research Fellow at London School of Economics (STICERD) — Consultant for Certara (pharmacometrics and health economics consulting) — Scientific Collaborator at Hasselt University (Centre for Statistics)
Short bio: I studied Mathematics (BSci, MSci, AGH Kraków), specialising in algorithmic theory, graph theory, probability. I did my PhD in Bayesian statistics at University of Hasselt (Belgium). My thesis was on hierarchical modelling (focus on meta-analyses) and Bayesian networks.
With Certara (since Sept 2014) I work on analyses that inform real-world effectiveness of treatments. This includes predictive, patient-level modelling (incl. PK/PD), (network) meta-analyses, infectious disease models (influenza), survival analysis. I also worked on PK/PD, PBPK, esp. in the context of checmical risk assessment.
With LSE (since May 2018), I work on Bayesian inference for modelling heterogeneity in treatment effects with with Rachael Meager (STICERD). I’m working on a new R package for evidence synthesis with Stan and also various research projects in development economics: in particular a hierarchical Bayesian model for a poverty alleviation study, with Andrew Gelman (Columbia University) and Dean Karlan (Northwestern Uni) as project advisors.
links: GitHub, LinkedIn, CV
Recent projects/talks/papers (Dec 2019)
- Modelling cyclical structures in Bayesian networks:
- Work with European Food Safety Authority (via Certara) on chemical risk assessment
- Short presentation on real world evidence in pharma research & medical publishing, from a discussion panel at European meeting for International Society for Medical Publication Professionals (via Analytica Laser/Certara)
Ongoing projects in the public domain
- baggr ; R package for meta-analyses with Stan; not yet on CRAN
- graph_sampler with Frederic Bois (INERIS) and Ghislaine Gayraud (UTC Compiegne); open-source (GNU Savannah) software in C for inferring Bayesian network structure, including efficient MCMC sampler over discrete space of graphs; also an R package
- rgraphsampler is an R package prototype (it works but it’s also raw) that allows to run the graph sampler code inside R
- httkgui/TKPlate with European Food Safety Authority; R package including Shiny app - a raw prototype for a graphical user interface for running generic toxicokinetic models, including ODE TK models in C; also on my GitHub
- survivalnma is a limited release of an R package I built internally at Certara for network meta-analyses of survival data (such as occurs in oncology), aimed at improving health technology assessment models
My Hasselt PhD is available online.
- Wiecek, Witold, Jean-Lou Dorne, Nadia Quignot, Camille Bechaux, and Billy Amzal. ‘A Generic Bayesian Hierarchical Model for the Meta-Analysis of Human Population Variability in Kinetics and Its Applications in Chemical Risk Assessment’. Computational Toxicology 12 (November 2019): 100106. https://doi.org/10.1016/j.comtox.2019.100106.
(arXiv only) Wiecek, Witold, Frederic Y. Bois, and Ghislaine Gayraud. ‘Structure Learning of Bayesian Networks Involving Cyclic Structures’. ArXiv:1906.04992 [Stat], 12 June 2019. http://arxiv.org/abs/1906.04992.
- Quignot, Nadia, Witold Wiecek, Billy Amzal, and Jean-Lou Dorne. The Yin-Yang of CYP3A4: A Bayesian Meta-Analysis to Quantify Inhibition and Induction of CYP3A4 Metabolism in Humans and Refine Uncertainty Factors for Mixture Risk Assessment. Archives of Toxicology, October 8, 2018. https://doi.org/10.1007/s00204-018-2325-6.
- Rajaram, Sankarasubramanian, Witold Wiecek, Richard Lawson, Betina T. Blak, Yanli Zhao, Judith Hackett, Robert Brody, Vishal Patel, and Billy Amzal. Impact of Increased Influenza Vaccination in 2-3-Year-Old Children on Disease Burden within the General Population: A Bayesian Model-Based Approach. PloS One 12, no. 12 (2017): e0186739. https://doi.org/10.1371/journal.pone.0186739.
- Rajaram, Sankarasubramanian, Witold Wiecek, Richard Lawson, Betina Blak, Yanli Zhao, Judith Hackett, Robert Brody, Tehseen Salimi, Billy Amzal, and Vishal Patel. A Retrospective Observational Analysis of Post-Pandemic Influenza-Related Outcomes in the United Kingdom, 2010-2014. Human Vaccines & Immunotherapeutics 14, no. 2 (01 2018): 368–77. https://doi.org/10.1080/21645515.2017.1403696.
- Schmidt, Elvira, Johanna Lister, Monika Neumann, Witold Wiecek, Shuai Fu, Anne-Lise Vataire, Jelena Sostar, Shengnan Huang, and Florence Marteau. Cabozantinib Versus Standard-of-Care Comparators in the Treatment of Advanced/Metastatic Renal Cell Carcinoma in Treatment-Naïve Patients: A Systematic Review and Network Meta-Analysis. Targeted Oncology 13, no. 2 (April 2018): 205–16. https://doi.org/10.1007/s11523-018-0559-0.
- Wiecek, Witold, and Helene Karcher. Nivolumab versus Cabozantinib: Comparing Overall Survival in Metastatic Renal Cell Carcinoma. PloS One 11, no. 6 (2016): e0155389. https://doi.org/10.1371/journal.pone.0155389.
(I included only the posters that were abstracted in literature.)
- Wiecek, Witold, Nadia Quignot, Billy Amzal, and Jean-Lou Dorne. TKPlate: R Package Prototype for TK Models Graphical Interface. Zenodo, 2019. https://doi.org/10.5281/zenodo.2548850.
- Dorne, J. -L. C. M., B. Amzal, N. Quignot, W. Wiecek, A. Grech, C. Brochot, R. Beaudouin, et al. “Reconnecting Exposure, Toxicokinetics and Toxicity in Food Safety: OpenFoodTox and TKplate for Human Health, Animal Health and Ecological Risk Assessment.” Toxicology Letters, ABSTRACTS of the 54th Congress of the European Societies of Toxicology (EUROTOX 2018) TOXICOLOGY OUT OF THE BOX Brussels, Belgium, 2nd – 5th of September, 2018, 295 (October 10, 2018): S29. https://doi.org/10.1016/j.toxlet.2018.06.1128.
- Dorne, J. -L. C. M., B. Amzal, N. Quignot, W. Wiecek, C. Bechaux, K. Darney, A. Grech, et al. “Developing TK Databases and Tools to Support Food Safety Assessment.” Toxicology Letters, ABSTRACTS of the 54th Congress of the European Societies of Toxicology (EUROTOX 2018) TOXICOLOGY OUT OF THE BOX Brussels, Belgium, 2nd – 5th of September, 2018, 295 (October 10, 2018): S5–6. https://doi.org/10.1016/j.toxlet.2018.06.023.
- Amzal, B., W. Wiecek, T. Obadia, and F. Benzaghou. Interval-Censored Survival Data Analysis: Learnings From Phase Iii Trial In Prostate Cancer. Value in Health 19, no. 3 (May 1, 2016): A98–99. https://doi.org/10.1016/j.jval.2016.03.1711.
- Karcher, H., W. Wiecek, M. Nikodem, E. Voss, A. Sena, and S. Cepeda. A NEW TOOL TO AUTOMATE NETWORK META-ANALYSES OF STUDIES EXTRACTED FROM CLINICALTRIALS.GOV. Value in Health 19, no. 3 (May 1, 2016): A91. https://doi.org/10.1016/j.jval.2016.03.1823.
- Wiecek, W., B. Amzal, S. Bakshi, V. Patel, and T. Van Staa. Age Related Consultation Rates of Clinically-Diagnosed Influenza And Acute Respiratory Illnesses Observed Through A Network of Gp Practices Across England. Value in Health 18, no. 7 (November 1, 2015): A579. https://doi.org/10.1016/j.jval.2015.09.1931.
- Wiecek, W., and H. Karcher. Comparing Cost-Effectiveness Of Emerging Drugs In Advanced Cancer Without Hazard Ratios For Progression. Value in Health 18, no. 7 (November 1, 2015): A688. https://doi.org/10.1016/j.jval.2015.09.2551.
- Wiecek, W., H. Karcher, B. Amzal, A. Beyer, T. Hoekstra, B. Fasolo, and J. L. Hillege. Impact of Drug’s Presentation on Patients’ Perception of Treatment’s Risks & Benefits Through New Ordinal Gee Modelling Method: Results from Imi Protect Wp6. Value in Health 18, no. 7 (November 1, 2015): A484–85. https://doi.org/10.1016/j.jval.2015.09.1326.
- Wiecek, W., M. Nikodem, and H. Karcher. Meta-Analyses Of Overall Survival In Metastatic Renal Cell Carcinoma. Value in Health 19, no. 3 (May 1, 2016): A140. https://doi.org/10.1016/j.jval.2016.03.1660.
- Karcher, H., W. Wiecek, R. Casciano, E. Coeytaux, S. Bixer, B. Amzal, and L. Abenhaim. Evaluating the Impact of PCSK9 Inhibitors on Cardiovascular Disease. Value in Health 20, no. 9 (October 1, 2017): A630. https://doi.org/10.1016/j.jval.2017.08.1404.