Carry out log rank test

Compute log rank test statistic on an endpoint.

Usage

fitLogrank(formula, placebo, data, alternative, ..., tidy = TRUE)

Arguments

formula

An object of class formula that can be used with survival::coxph. Must consist arm and endpoint in data. No covariate is allowed. Stratification variables are supported and can be added using strata(...).

placebo

character. String of placebo in data$arm.

data

data frame. Usually it is a locked data.

alternative

a character string specifying the alternative hypothesis, must be one of "greater" or "less". No default value. "greater" means superiority of treatment over placebo is established by an hazard ratio greater than 1.

...

subset condition that is compatible with dplyr::filter. survival::coxph with ties = "exact" will be fitted on this subset only. This argument could be useful to create a subset of data for analysis when a trial consists of more than two arms. By default it is not specified, all data will be used to fit the model. More than one conditions can be specified in ..., e.g., fitLogrank(formula, data, arm %in% c('pbo', 'low dose'), pfs > 0.5), which is equivalent to fitLogrank(formula, data, arm %in% c('pbo', 'low dose') & pfs > 0.5).

tidy

logical. FALSE if more information are returned. Default TRUE.

Value

a data frame with three columns:

arm

name of the treatment arm.

placebo

name of the placebo arm.

p

one-sided p-value for log-rank test (treated vs placebo).

info

the number of events of the endpoint in the subset.

z

the z statistics of log hazard ratios.