Abstract
The partial likelihood theory for survival data, introduced in Chap. 5, allows one to model survival times while accommodating covariate information. An important caveat to this theory is that the values of the covariates must be determined at time t = 0, when the patient enters the study, and remain constant thereafter. This issue arises with survival data because such data evolve over time, and it would be improper to use the value a covariate to model survival information that is observed before the covariate’s value is known. To accommodate covariates that may change their value over time (“time dependent covariates”) , special measures are necessary to obtain valid parameter estimates. An intervention that occurs after the start of the trial, or a covariate (such as air pollution exposure) that changes values over the course of the study are two examples of time dependent variables.
The original version of this chapter was revised. An erratum to this chapter can be found at DOI 10.1007/978-3-319-31245-3_13
An erratum to this chapter can be found at http://dx.doi.org/10.1007/978-3-319-31245-3_13
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Clark, T.G., Bradburn, M.J., Love, S.B., Altman, D.G.: Survival analysis part I: Basic concepts and first analyses. Br. J. Cancer 89(2), 232–238 (2003)
Gail, M.H.: Does cardiac transplantation prolong life? A reassessment. Ann. Intern. Med. 76(5), 815–817 (1972)
Therneau, T., Crowson, C.: Using time dependent covariates and time dependent coefficients in the cox model. Vignette for R survival package, http://cran.r-project.org/web/packages/survival, July 2015
Therneau, T.M., Grambsch, P.M.: Modeling Survival Data: Extending the Cox Model. Springer, New York (2000)
Author information
Authors and Affiliations
Rights and permissions
Copyright information
© 2016 Springer International Publishing Switzerland
About this chapter
Cite this chapter
Moore, D.F. (2016). Time Dependent Covariates. In: Applied Survival Analysis Using R. Use R!. Springer, Cham. https://doi.org/10.1007/978-3-319-31245-3_8
Download citation
DOI: https://doi.org/10.1007/978-3-319-31245-3_8
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-31243-9
Online ISBN: 978-3-319-31245-3
eBook Packages: Mathematics and StatisticsMathematics and Statistics (R0)