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Table 3 Stata specification for each model

From: Identification of risk factors for hospital admission using multiple-failure survival models: a toolkit for researchers

Model type Commands to convert dataset as formatted in Extract 2 to a format suitable for model fitting Description of commands to convert dataset Commands to fit models Description of commands to fit models
Time to first event Cox stset End, failure(Failure==1) id(ID) origin(time Clinic) enter(time Clinic) scale(365.25) time0(Start) origin(time Clinic) and enter(time Clinic) specify that the individual first becomes at risk after the clinic date stcox varlist varlist represents a list of predictor variables in the model
Andersen and Gill stset End, failure(Failure==1) id(ID) origin(time Clinic) enter(time Clinic) scale(365.25) time0(Start) exit(time.) scale(365.25) ensures that time is measured in years as opposed to days stcox varlist, efron robust efron specifies the use of the Efron method for analysing ties in the data
Prentice, Williams and Peterson Total Time stset End, failure(Failure==1) id(ID) origin(time Clinic) enter(time Clinic) scale(365.25) time0(Start) exit(time.) time0(Start) specifies that 'Start' is the beginning of the time interval spanned by each record stcox varlist, efron robust strata(Risk_set) robust specifies that robust variance estimation is used to account for within-subject correlation of failure times
exit(time.) ensures that an individual’s failures after the first are also recognised   strata(Risk_set) ensures that a stratified cox model is fitted with a different underlying risk for each ordered failure event
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BMC Medical Research Methodology

ISSN: 1471-2288

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