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Open Access Research article

Competing risk models to estimate the excess mortality and the first recurrent-event hazards

Aurélien Belot12345*, Laurent Remontet1234, Guy Launoy6, Valérie Jooste7 and Roch Giorgi8

Author Affiliations

1 Hospices Civils de Lyon, Service de Biostatistique, Lyon, France

2 Université de Lyon, Lyon, France

3 Université Lyon 1, Villeurbanne, France

4 CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Equipe Biostatistique-Santé, Villeurbanne, France

5 Institut de Veille Sanitaire, Département des Maladies Chroniques et des Traumatismes, Saint-Maurice, France

6 INSERM ERI3 « Cancers & Populations », Caen, France

7 Registre Bourguignon des Cancers Digestifs, Inserm U866, CHU Dijon, Dijon, France

8 Laboratoire d'Enseignement et de Recherche sur le Traitement de l'Information Médicale, EA 3283, Aix-Marseille Université, Faculté de Médecine, Marseille, France

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BMC Medical Research Methodology 2011, 11:78  doi:10.1186/1471-2288-11-78

Published: 25 May 2011

Abstract

Background

In medical research, one common competing risks situation is the study of different types of events, such as disease recurrence and death. We focused on that situation but considered death under two aspects: "expected death" and "excess death", the latter could be directly or indirectly associated with the disease.

Methods

The excess hazard method allows estimating an excess mortality hazard using the population (expected) mortality hazard. We propose models combining the competing risks approach and the excess hazard method. These models are based on a joint modelling of each event-specific hazard, including the event-free excess death hazard. The proposed models are parsimonious, allow time-dependent hazard ratios, and facilitate comparisons between event-specific hazards and between covariate effects on different events. In a simulation study, we assessed the performance of the estimators and showed their good properties with different drop-out censoring rates and different sample sizes.

Results

We analyzed a population-based dataset on French colon cancer patients who have undergone curative surgery. Considering three competing events (local recurrence, distant metastasis, and death), we showed that the recurrence-free excess mortality hazard reached zero six months after treatment. Covariates sex, age, and cancer stage had the same effects on local recurrence and distant metastasis but a different effect on excess mortality.

Conclusions

The proposed models consider the excess mortality within the framework of competing risks. Moreover, the joint estimation of the parameters allow (i) direct comparisons between covariate effects, and (ii) fitting models with common parameters to obtain more parsimonious models and more efficient parameter estimators.

Keywords:
Excess hazard; Competing risks; Time-dependent hazard ratio; Regression splines; Cancer; Population-based study