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Cost‐effectiveness analysis in colorectal cancer using a semi‐Markov model
Author(s) -
Castelli Christel,
Combescure Christophe,
Foucher Yohann,
Daures JeanPierre
Publication year - 2007
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.3112
Subject(s) - statistics , covariate , weibull distribution , markov chain , markov model , colorectal cancer , medicine , parametric statistics , hazard ratio , mathematics , logistic regression , computer science , econometrics , cancer , confidence interval
Cost and effectiveness are usually modeled according to one studied event or one health state with parametric or non‐parametric methods. In this paper, we propose an original method for assessing total costs while incorporating the dynamics of change in the health status of patients. A semi‐Markov model in which the distributions of sojourn times are explicitly defined is developed. The hazard function of sojourn times is modeled by Weibull distributions specific to each transition. A vector of covariates is incorporated into the hazard function of each transition. From a regression model for costs, a cumulative cost function is derived. An estimation of the mean cost per patient in each state defined in the semi‐Markov model could thus be made, and this enables us to identify the determinants of direct costs. The results of incremental net benefit (INB) are assessed using the bootstrap method. A cost‐effectiveness analysis is performed in order to compare two strategies of follow‐up in the colorectal cancer study. Two hundred and forty patients were enrolled in this study. Three health states are defined for patients with curative resection of colorectal cancer: alive without relapse, alive with relapse, and dead. The mean survival is 4.35 and 4.12 years, respectively, in the standard and moderate follow‐up groups. We show that mean cost differs significantly by follow‐up strategy and Dukes stage. Finally, the INB is assessed and this indicates that neither of the strategies compared was more cost‐effective than the other. Copyright © 2007 John Wiley & Sons, Ltd.