survst: Function for survival starting values
In mesudell/joineRmeta: Joint Modelling for Meta-Analytic (Multi-Study) Data

Internal function to estimate the starting values for the EM algorithm for the survival sub-model

1	survst(survdat, surv.formula, survdat2, strat, study.name = NULL)

`survdat`	the survival data with factors and interaction terms expanded, ordered by increasing survival time
`surv.formula`	a formula object with the survival time, censoring indicator and the covariates to include in the survival sub-model. The response must be a survival object as returned by the `Surv` function.
`survdat2`	the survival data with original variables (factors and interaction terms not expanded), ordered by increasing survival time
`strat`	logical value: if `TRUE` then the survival sub-model is calculated with a baseline stratified by study. Otherwise baseline is unstratified
`study.name`	a character string denoting the name of the variable in the baseline dataset in `data` holding study membership, for example `study.name = 'study'`.

A list of the results from the initial survival fit is returned. This list contains the following elements:

beta2: a vector of the estimated coefficients for fixed effects included in the survival sub-model. If there are no fixed effects included in the survival sub-model then this returns NULL

haz: the estimate of the baseline hazard estimated from the separate survival model. If strat = TRUE then this is a list of length equal to the number of studies in the dataset, each element of which is a vector of length equal to the number of events in each study. If strat = FALSE then this is a vector of length equal to the number of events in the entire dataset.
rs: the number of events that have occured by the individual in question's survival time. If strat = TRUE then this is a list of length equal to the number of studies in the dataset, each element of which is a vector of length equal to the number of individuals in each study. If strat = FALSE then this is a vector of length equal to the number of individuals in the entire dataset.
sf: the survival times where at least one event was observed. If strat = TRUE then this is a list of length equal to the number of studies in the dataset, each element of which is a vector of length equal to the number of events in each study. If strat = FALSE then this is a vector of length equal to the number of events in the entire dataset.
nev: the number of events that occur at each unique event time. If strat = TRUE then this is a list of length equal to the number of studies in the dataset, each element of which is a vector of length equal to the number of events in each study. If strat = FALSE then this is a vector of length equal to the number of events in the entire dataset.
log.like.surv: the value of the log-likelihood from the separate survival analysis
modelfit: the initial survival model fit, fitted using the coxph function from the survival package.