Biomaterial Database

Time-dependent effects of fixed covariates in Cox regression. 1995

P J Verweij, and H C van Houwelingen

Department of Medical Statistics, Leiden University, The Netherlands.

A nonparametric modification is proposed for Cox's proportional hazards model (Cox, 1972, Journal of the Royal Statistical Society, Series B 34, 187-220), where the covariates are fixed, but their effects are allowed to vary in time. Parameters are introduced for the covariate effects at the (uncensored) survival times. Estimates are obtained by maximizing the penalized partial log-likelihood that arises if a penalty function of the first order differences of consecutive parameters is subtracted from the partial log-likelihood. The choice of the smoothing parameter, which determines the weight of the penalty, is based on Akaike's Information Criterion. The methods are illustrated in a set of ovarian cancer data and in a set of kidney transplantation data.

UI	MeSH Term	Description	Entries
D009367	Neoplasm Staging	Methods which attempt to express in replicable terms the extent of the neoplasm in the patient.	Cancer Staging,Staging, Neoplasm,Tumor Staging,TNM Classification,TNM Staging,TNM Staging System,Classification, TNM,Classifications, TNM,Staging System, TNM,Staging Systems, TNM,Staging, Cancer,Staging, TNM,Staging, Tumor,System, TNM Staging,Systems, TNM Staging,TNM Classifications,TNM Staging Systems
D010051	Ovarian Neoplasms	Tumors or cancer of the OVARY. These neoplasms can be benign or malignant. They are classified according to the tissue of origin, such as the surface EPITHELIUM, the stromal endocrine cells, and the totipotent GERM CELLS.	Cancer of Ovary,Ovarian Cancer,Cancer of the Ovary,Neoplasms, Ovarian,Ovary Cancer,Ovary Neoplasms,Cancer, Ovarian,Cancer, Ovary,Cancers, Ovarian,Cancers, Ovary,Neoplasm, Ovarian,Neoplasm, Ovary,Neoplasms, Ovary,Ovarian Cancers,Ovarian Neoplasm,Ovary Cancers,Ovary Neoplasm
D005260	Female		Females
D006684	HLA-DR Antigens	A subclass of HLA-D antigens that consist of alpha and beta chains. The inheritance of HLA-DR antigens differs from that of the HLA-DQ ANTIGENS and HLA-DP ANTIGENS.	HLA-DR,Antigens, HLA-DR,HLA DR Antigens
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000970	Antineoplastic Agents	Substances that inhibit or prevent the proliferation of NEOPLASMS.	Anticancer Agent,Antineoplastic,Antineoplastic Agent,Antineoplastic Drug,Antitumor Agent,Antitumor Drug,Cancer Chemotherapy Agent,Cancer Chemotherapy Drug,Anticancer Agents,Antineoplastic Drugs,Antineoplastics,Antitumor Agents,Antitumor Drugs,Cancer Chemotherapy Agents,Cancer Chemotherapy Drugs,Chemotherapeutic Anticancer Agents,Chemotherapeutic Anticancer Drug,Agent, Anticancer,Agent, Antineoplastic,Agent, Antitumor,Agent, Cancer Chemotherapy,Agents, Anticancer,Agents, Antineoplastic,Agents, Antitumor,Agents, Cancer Chemotherapy,Agents, Chemotherapeutic Anticancer,Chemotherapy Agent, Cancer,Chemotherapy Agents, Cancer,Chemotherapy Drug, Cancer,Chemotherapy Drugs, Cancer,Drug, Antineoplastic,Drug, Antitumor,Drug, Cancer Chemotherapy,Drug, Chemotherapeutic Anticancer,Drugs, Antineoplastic,Drugs, Antitumor,Drugs, Cancer Chemotherapy
D001699	Biometry	The use of statistical and mathematical methods to analyze biological observations and phenomena.	Biometric Analysis,Biometrics,Analyses, Biometric,Analysis, Biometric,Biometric Analyses
D016013	Likelihood Functions	Functions constructed from a statistical model and a set of observed data which give the probability of that data for various values of the unknown model parameters. Those parameter values that maximize the probability are the maximum likelihood estimates of the parameters.	Likelihood Ratio Test,Maximum Likelihood Estimates,Estimate, Maximum Likelihood,Estimates, Maximum Likelihood,Function, Likelihood,Functions, Likelihood,Likelihood Function,Maximum Likelihood Estimate,Test, Likelihood Ratio
D016016	Proportional Hazards Models	Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study population is multiplicative and does not change over time.	Cox Model,Cox Proportional Hazards Model,Hazard Model,Hazards Model,Hazards Models,Models, Proportional Hazards,Proportional Hazard Model,Proportional Hazards Model,Cox Models,Cox Proportional Hazards Models,Hazard Models,Proportional Hazard Models,Hazard Model, Proportional,Hazard Models, Proportional,Hazards Model, Proportional,Hazards Models, Proportional,Model, Cox,Model, Hazard,Model, Hazards,Model, Proportional Hazard,Model, Proportional Hazards,Models, Cox,Models, Hazard,Models, Hazards,Models, Proportional Hazard
D016019	Survival Analysis	A class of statistical procedures for estimating the survival function (function of time, starting with a population 100% well at a given time and providing the percentage of the population still well at later times). The survival analysis is then used for making inferences about the effects of treatments, prognostic factors, exposures, and other covariates on the function.	Analysis, Survival,Analyses, Survival,Survival Analyses