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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/9243

Title: Validation of prognostic indices using the frailty model
Authors: LEGRAND, Catherine
Ducrocq, V.
Issue Date: 2009
Publisher: SPRINGER
Citation: LIFETIME DATA ANALYSIS, 15(1). p. 59-78
Abstract: A major issue when proposing a new prognostic index is its generalisibility to daily clinical practice. Validation is therefore required. Most validation techniques assess whether "on average" the results obtained by the prognostic index in classifying patients in a new sample of patients are similar to the results obtained in the construction set. We introduce a new important aspect of the generalisibility of a prognostic index: the heterogeneity of the prognostic index risk group hazard ratios over different centers. If substantial variability between centers exists, the prognostic index may have no discriminatory capability in some of the centers. To model such heterogeneity, we use a frailty model including a random center effect and a random prognostic index by center interaction. Statistical inference is based on a Bayesian approach using a Laplacian approximation for the marginal posterior distribution of the variances of the random effects. We investigate different ways to summarize the information available from this marginal posterior distribution. Our approach is applied to a real bladder cancer database for which we demonstrate how to investigate and interpret heterogeneity in prognostic index effect over centers.
Notes: [Legrand, C.; Sylvester, R.] European Org Res Treatment Canc, B-1200 Brussels, Belgium. [Legrand, C.] Univ Catholique Louvain, B-1348 Louvain La Neuve, Belgium. [Duchateau, L.] Univ Ghent, Fac Vet Med, Dept Physiol & Biometr, B-9820 Merelbeke, Belgium. [Janssen, P.] Hasselt Univ, Ctr Stat, B-3590 Diepenbeek, Belgium. [Ducrocq, V.] INRA, Genet Quantitat & Appl Stn, F-78352 Jouy En Josas, France.
URI: http://hdl.handle.net/1942/9243
DOI: 10.1007/s10985-008-9092-2
ISI #: 000262483200004
ISSN: 1380-7870
Category: A1
Type: Journal Contribution
Validation: ecoom, 2010
Appears in Collections: Research publications

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