Date d introduction 30 09 2007 entreprise (nom, site internet
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Date d'introduction 30 09 2007 entreprise (nom, site internet

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30/09/2007 Date d'introduction Entreprise (Nom, site internet) IDDI, http://www.iddi.com Logo Nom, Prénom du contact, marc.buyse@iddi.com téléphone, adresse e-mail du linda.danielson@iddi.

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________________________________________________________________________
Formulaire de propositions de sujets de TFE- Action de formation BioW in
1
Date d'introduction
30/09/2007
Entreprise
(Nom, site internet)
IDDI,
http://www.iddi.com
Logo
Nom, Prénom du contact,
téléphone, adresse e-mail du
contact*
marc.buyse@iddi.com
linda.danielson@iddi.com
Lieu
Avenue Provinciale, 30
1340 Ottignies / Louvain-La-Neuve - Belgium
Département de l'entreprise
biostatistique
Niveau d'études concerné
1
universitaire
Type de stage
1
Mémoire
Thématique
Use of Cox regression model in randomized clinical trials
This project will consist of
1. extracting from the medical literature a large number of
papers (50 to 100) describing the results of randomized trials
in which the Cox model was used to adjust the treatment
comparison;
2. comparing the significance of the adjusted and the
unadjusted treatment comparisons, using a correlation
approach and concordance statistics;
3. exploring (through simulations) the impact of non
proportional hazards on the outcome of early breast cancer
trials, using either a Cox regression model, a stratified or an
unstratified logrank test;
4. writing a paper with the findings.
Background
Sir David Cox introduced his famed regression model in
1972. His initial exposition of the model remains the most
frequently cited scientific paper of all times. Although the
model may be extremely useful in epidemiology to account
simultaneously for many confounders, it does make the
assumption of proportional hazards, which may or may not
be valid. In the context of randomized trials, use of the Cox
model is unnecessary at best (a stratified logrank is
appropriate to account for a few truly important prognostic
factors) and miseleading at worst (because of strong non
proportionality of the hazards and/or multicollinearity of the
prognostic factors included in the model).
It would therefore be of interest to investigate use of the Cox
model in randomized clinical trials from two perspectives:
(a) is there empirical evidence that published results of past
trials are unaffected by use of the Cox model? and
(b) is there empirical evidence from current trials that strong
departures from proportional hazards and/or correlations
between the baseline covariates spuriously affect the
statistical significance of treatment comparisons?
Formations visées
Statistique, mathématique, biostatistique
Techniques abordées
Compétences visées
Compétences requises
A good knowledge of survival analysis is needed for the
project (logrank test, Cox regression model). The student
should additionally have a broad interest in clinical trial
methodology. Good proficiency in English is a must.
Référénces
REFERENCES
1. Cox DR, J R Stat Soc (B) 1972;34187.
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