Publicaties
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Assessing Performance and Clinical Usefulness in Prediction Models With Survival Outcomes: Practical Guidance for Cox Proportional Hazards Models KU Leuven
Risk prediction models need thorough validation to assess their performance. Validation of models for survival outcomes poses challenges due to the censoring of observations and the varying time horizon at which predictions can be made. This article describes measures to evaluate predictions and the potential improvement in decision making from survival models based on Cox proportional hazards regression. As a motivating case study, the authors ...
Goodness-of-fit tests for the frailty distribution in proportional hazards models with shared frailty. Universiteit Hasselt KU Leuven
Frailty models account for the clustering present in event time data. A proportional hazards model with shared frailties expresses the hazard for each subject.Often a one-parameter gamma distribution is assumed for the frailties. In this paper, we construct formal goodness-of-fit tests to test for gamma frailties. We construct a new class of frailty models that extend the gamma frailty model by using certain polynomial expansions that are ...
Goodness-of-fit tests in proportional hazards models with random effects KU Leuven
This paper deals with testing the functional form of the covariate effects in a Cox proportional hazards model with random effects. We assume that the responses are clustered and incomplete due to right censoring. The estimation of the model under the null (parametric covariate effect) and the alternative (nonparametric effect) is performed using the full marginal likelihood. Under the alternative, the nonparametric covariate effects are ...
Accelerated failure time vs Cox proportional hazards mixture cure models: David vs Goliath? KU Leuven
Lagged duration dependence in mixed proportional hazard models Universiteit Gent
Predictors of time to relapse in amphetamine-type substance users in the matrix treatment program in Iran : a Cox proportional hazard model application Universiteit Gent Universiteit Antwerpen
An application of Harrell's C-index to PH frailty models Universiteit Hasselt KU Leuven
Frailty models are encountered in many medical applications, yet little research has been devoted to develop measures that quantify the predictive ability of these models. In this paper, we elaborate on the concept of the concordance probability to clustered data, resulting in an 'Overall Conditional C-index' or C-O,C-C and an 'Overall Marginal C-index' or C-O,C-M. Both Overall C-indices can be split up into a 'Between Conditional' or C-B,C-C ...
Non-Linear Survival Models and Their Applications Within Breast Cancer Prognosis (Niet-lineaire overlevingsmodellen en hun toepassingen in borstkankerprognose) KU Leuven
Everybody is confronted with the diagnosis of cancer during their life. If not personally, it might be a family member or a friend. The diagnosis of cancer creates a feeling of fear. Fear for the unknown, fear for the therapy, fear to die. Thanks to the knowledge of clinical doctors the patients can be informed on their disease and can be treated adequately. In order to decide on treatment options, estimation of risk of survival is crucial. ...