Environmental Epidemiology

Karen Leffondré received a PhD in Biostatistics in 1999 from the University of Paris-Sud 11 and INSERM U472 (France). She then did a post-doc at McGill University (Division of Clinical Epidemiology), and since 2003, she has been an Assistant Professor at theUniversity of Montreal (Department of Social and Preventive Medicine). She is also a Researcher at the Research Center of the CHUM (Population Health Axis).

Research

Her research interests are the development and application of new statistical methods for the analysis of epidemiological data. In particular, she is interested in the modelling of time-varying exposures such as smoking history. Her research projects are based on simulation studies, as well as on the analysis of real epidemiological data. She currently focuses on the assessment of time-varying exposures in case-control studies (with applications to lung cancer).

Selected Publications

1. Leffondré K, Lellouch J, Com-Nougué C, Moreau T. Optimality of non-parametric tests for association between survival time and continuous covariate. Communications in Statistics - Theory and Methods, 2001; 30(5):913-929.
2. MacDougall LA, Gyorkos TW, Leffondré K, Abrahamowicz M, Tessier D, Ward BJ, MacLean JD. Increasing referral of at-risk travellers to travel health clinics: Evaluation of a health promotion intervention targeted to travel agents. Journal of Travel Medicine, 2001; 8(5):232-242.
3. Leffondré K, Abrahamowicz M, Siemiatycki J, Rachet B. Modeling smoking history: A comparison of different approaches. American Journal of Epidemiology, 2002; 156(9):813-823.
4. Leffondré K, Abrahamowicz M, Siemiatycki J, Rachet B. The authors reply Re: "Modeling smoking history: A comparison of different approaches". American Journal of Epidemiology 2003; 158(4):393-394.
5. Abrahamowicz M, Schopflocher T, Leffondré K, du Berger R, Krewski D. Flexible modeling of the exposure-response relationship between long-term exposure to average levels of particulate air pollution and mortality in the American Cancer Society study. Journal of Toxicology and Environmental Health Part A, 2003; 66(16-19):1625-1654
6. Leffondré K, Abrahamowicz M, Siemiatycki J. Evaluation of Cox's model and logistic regression for matched case-control data with time-dependent covariates: A simulation study. Statistics in Medicine, 2003; 22(24):3781-3794.
7. Sewitch MJ, Leffondré K, Dobkin PL. Clustering patients according to health perceptions: Relationships to psychosocial characteristics and medication nonadherence. Journal of Psychosomatic Research, 2004; 56(3):323-332.
8. Abrahamowicz M, du Berger R, Krewski D, Burnett R, Bartlett G, Tamblyn, R, Leffondré K. Bias due to aggregation of covariates in the Cox regression model. American Journal of Epidemiology, 2004; 160(7):696-706.
9. Leffondré K, Abrahamowicz M, Regeasse A, Hawker GA, Badley EM, McCusker J, Belzile E. Statistical measures were proposed for identifying longitudinal patterns of change in quantitative health indicators. Journal of Clinical Epidemiology, 2004; 57(10):1049-1062.
10. Rachet B, Siemiatycki J, Abrahamowicz M, Leffondré K. A flexible modelling approach estimated the respective effects of different elements of smoking behaviour on lung cancer risk. Journal of Clinical Epidemiology, 2004; 57(10):1076-1085.
11. Vassiliou MC, Feldman LS, AndrewCG, Bergman S, Leffondré K, Stanbridge D, FriedGM. A global assessment tool for evaluation of intraoperative laparoscopic skills. American Journal of Surgery, 2005; 190(1):107-113.
12. Fortes C, Mastroeni S, Leffondré K, Sampogna F, Melchi CF, Mazzoti E, Pasquini P, Abeni D, for the IDI Multipurpose Psoriasis research on Vital Experiences (IMPROVE) Study Group. Relationship between smoking and the clinical severity of psoriasis. Archives of Dermatology, 2005; 141(12):1580-1584.
13. Mahmud M, Abrahamowicz M, Leffondré K, Chaubey YP. Selecting the optimal transformation of a continuous covariate in Cox's regression: Implications for hypothesis testing. Communications in Statistics - Simulation and Computation, 2006; 35(1) : 27-45.
14. Vassiliou MC, Ghitulescu GA, Feldman LS, Stanbridge D, Leffondré K, Sigman HH, Fried GM. The MISTELS program to measure technical skill in laparoscopic surgery: Evidence for reliability. Surgical Endoscopy and Other Interventional Techniques, 2006; 20(5) : 744-747.
15. Leffondré K, Abrahamowicz M, Siemiatycki J, Xiao Y. Modeling smoking history using a comprehensive smoking index : Application to lung cancer. Statistics in Medicine, 2006; 25(24) : 4132-4146.
16. Feldman DE, Bernatsky S, Haggerty J, Leffondré K, Tousignant P, Roy Y, Xiao Y, Zummer M, Abrahamowicz M. Delay in consultation with specialists for persons with suspected new-onset rheumatoid arthritis: a population-based study. Arthritis & Rheumatism, 2007; 57(8).