- Email Address(es)
- Office Phone
- 416-813-7654 x301031
- Office Address
- Hospital for Sick Children 555 University Avenue Toronto, ON M5G 1X8
- Hospital for Sick Children
- Biostatistics Division
- Associate Professor
- SGS Status
- Full Member
- Appointment Status
- Status Only
- Currently Accepting Doctoral Students?
I help ensure that healthcare is based on high-quality evidence by:
- developing new statistical methods to handle the complex data that often arise in medical research
- working with colleagues to choose the most appropriate design and analysis for research
- training graduate students in statistical methods
I have several projects in these areas that are suitable for students considering Master’s or Doctoral work; please contact me if interested.
Education & Training History
PhD, Biostatistics, University of Toronto
Certificate of Advanced Studies in Mathematics, University of Cambridge
BA, Mathematics, University of Cambridge
Senior Scientist, The Hospital for Sick Children
Primary Teaching Responsibilities
Statistical Analysis of Health Economic Data (co-taught with Dr Anna Heath)
Professional Summary & Appointments
Senior Scientist, Child Health Evaluative Sciences, Hospital for Sick Children (2016-present)
Scientist, Child Health Evaluative Sciences, Hospital for Sick Children (2013-2016)
Associate Professor, Dalla Lana School of Public Health, University of Toronto (2013-present)
Biostatistician, St Joseph’s Healthcare Hamilton (2007-2013)
Associate Professor, Depeartment of Clinical Epidemiology & Biostatistics, McMaster University (2012-2013)
Assistant Professor, Depeartment of Clinical Epidemiology & Biostatistics, McMaster University (2007-2012)
Postdoctoral Fellow, Department of Statistics and Actuarial Science, University of Waterloo (2006)
Medical Statistician, Centre for Applied Medical Statistics, Department of Public Health and Primary Care, University of Cambridge (2000-2002))
Honours & Awards
CIHR New Investigator Award (2012-2018)
Young Investigator Award of the Section on Teaching Statistics in the Health Sciences, American Statistical Association (2008)
Schuldham Plate, Gonville & Caius College, University of Cambridge (1999)
Current Research Projects
- Methodology for irregularly observed longitudinal data
Longitudinal data are useful for understanding how disease evolves over time. Often longitudinal data can be collected through clinic based cohorts in which patients are enrolled in the cohort at diagnosis, followed up as medically necessary, and data are gathered through a chart review. This is an efficient and low cost approach to data collection. However, since patients tend to visit more often when unwell, this can lead to overestimation of the burden of disease unless accounted for appropriately. I develop analytic methods to handle the informative nature of the visit process.
- Methodology for health utilities
Health utilities are used in economic evaluations to help assess cost-effectiveness of treatments, and so ultimately contribute to decisions on which treatments should be publicly funded. I am interested in measurement of health utilities, in particular a) correctly quantifying the statistical uncertainty in these measurements, and b) reducing the extent of uncertainty. This is important as it reduces the risk of funding treatments that are not cost-effective, this enabling better use of limited resources.
- Rose Garrett (2018-present)
- Kuan Liu (2015-present)
- Shahriar Shams (2014-present)
- Armend Lokku (2014-2020) Summary Measures for Quantifying the Extent of Visit Irregularity in Longitudinal Data
- Kelvin Chan (2012-2016) Addressing Uncertainties in Health Utilities
- Qing Guo (2008-2013) Sample size calculations in fMRI studies
If you are a prospective doctoral student interested in studying under my supervision, I would be happy to chat with you. Please choose and read a paper from the Longitudinal data or Health Utilities sections below; we can schedule a call to discuss it and explore potential research topics arising from the paper. If you do not have library access to the full texts, please just let me know and I will provide you with them.
* indicates a student under my supervision
See here for a more complete list.
Pullenayegum EM. Meeting the Assumptions of Inverse-Intensity Weighting for Longitudinal Data Subject to Irregular Follow-Up: Suggestions for the Design and Analysis of Clinic-Based Cohort Studies. Epidemiologic Methods 2020 9 (1)
Lokku A*, Lim LS, Birken CS, Pullenayegum EM. Summarizing the extent of visit irregularity in longitudinal data. BMC Medical Research Methodology 2020 20, 1-9
Liu K*, Saarela O, Feldman BM, Pullenayegum E. Estimation of causal effects with repeatedly measured outcomes in a Bayesian framework. Statistical Methods in Medical Research (in press)
Farzanfar D*, Abumuamar A, Kim J, Sirotich E, Wang Y, Pullenayegum EM. Longitudinal studies that use data collected as part of usual care risk reporting biased results: a systematic review. BMC Medical Research Methodology. 2017 Sep 6;17(1):133. doi: 10.1186/s12874-017-0418-1. PubMed PMID: 28877680.
Pullenayegum EM, Lim LS. Longitudinal data subject to irregular observation: A review of methods with a focus on visit processes, assumptions, and study design. Stat Methods Med Res. 2016 Dec;25(6):2992-3014.
Pullenayegum EM. Multiple outputation for the analysis of longitudinal data subject to irregular observation. Stat Med. 2015 Dec 13. doi: 10.1002/sim.6829. [Epub ahead of print] PubMed PMID: 26661690.
Pullenayegum EM, Feldman BM. Doubly robust estimation, optimally truncated inverse-intensity weighting and increment-based methods for the analysis of irregularly observed longitudinal data. Statistics in Medicine. 2013 Mar 15; 32(6):1054-72. doi:10.1002/sim.5640.
Waudby-Smith I, Pickard AS, Xie F, Pullenayegum EM. Using Both Time Tradeoff and Discrete Choice Experiments in Valuing the EQ-5D: Impact of Model Misspecification on Value Sets. Medical Decision Making (in press)
Shams S*, Pullenayegum E. Design and sample size considerations for valuation studies of multi‐attribute utility instruments. Statistics in Medicine (in press)
Chan KKW, Pullenayegum EM. The Theoretical Relationship between Sample Size and Expected Predictive Precision for EQ-5D Valuation Studies: A Mathematical Exploration and Simulation Study. Medical Decision Making 2020 40 (3), 339-347
Pullenayegum EM, Pickard AS, Xie F. Latent Class Models Reveal Poor Agreement between Discrete Choice and Time Trade-off Preferences. Medical Decision Making 2019 39 (4), 421-436
Shams S*, Pullenayegum EM. Reducing Uncertainty in EQ-5D Value Sets: The Role of Spatial Correlation. Medical Decision Making. 2019 Feb; 39(2):91-99. doi: 10.1177/0272989X18821368. Epub 2019 Jan 24. PubMed PMID: 30678526
Chan KKW*, Xie F, Willan AR, Pullenayegum EM. Conducting EQ-5D Valuation Studies in Resource-Constrained Countries: The Potential Use of Shrinkage Estimators to Reduce Sample Size. Medical Decision Making. 2017 Aug 1:272989X17725748.doi: 10.1177/0272989X17725748. [Epub ahead of print] PubMed PMID: 28823185
Pullenayegum EM, Sunderland K*, Johnson JA, Xie F. Handling regional variation in health state preferences within a country: a methodological framework. Medical Decision Making. 2017 Apr;37(3):252-261. doi: 10.1177/0272989X16651885.
Chan KKW*, Xie F, Willan AR, Pullenayegum EM. Underestimation of Variance of Predicted Health Utilities Derived from Multi-Attribute Utility Instruments: The Use of Multiple Imputation as a Potential Solution. Medical Decision Making. 2017 Apr;37(3):262-272. doi: 10.1177/0272989X16650181. Epub 2016 Jul 10
Pullenayegum EM, Chan KKW*, Xie F. Quantifying Parameter Uncertainty in EQ-5D-3L Value Sets and Its Impact on Studies That Use the EQ-5D-3L to Measure Health Utility: A Bayesian Approach. Med Decis Making. 2016 Feb;36(2):223-33. doi: 10.1177/0272989X15591966. Epub 2015 Jul 2. PubMed PMID: 26139449.
Chan KKW*, Gupta M, Willan A, Pullenayegum EM. Underestimation of Uncertainties in Health Utilities derived from Mapping Algorithms involving Health Related Quality of Life Measures: Statistical Explanations and Potential Remedies. Medical Decision Making. 2014 Oct; 34(7):863-72. doi: 10.1177/0272989X13517750. Epub 2014 Jan 9. PubMed PMID: 24407513.
Pullenayegum EM, Platt RW, Barwick M, Feldman BM, Offringa M, Thabane L. Knowledge translation in biostatistics: a survey of current practices, preferences, and barriers to the dissemination and uptake of new statistical methods. Stat Med. 2016 Mar 15;35(6):805-18. doi: 10.1002/sim.6633. Epub 2015 Aug 25. PubMed PMID: 26307183.
R package IrregLong for analysing longitudinal data subject to irregular observation