Survminer, survival package: What is the difference between the "survdiff" log-rank and "regular" log-rank tests?

Question

I am using the survminer survival package in R. To compute p values to compare survival curves, I am using the surf_pvalue function.

With this function, you can determine the log-rank p value in two different ways. One is called "survdiff", the other "1" or "LR". See this link for more info. The second says that it is a "regular log-rank test, sensitive to detect late differences", but what are the differences between the two. Does anyone know?

Thank you.

Purely stats knowledge questions belong on CrossValidated.com. Voting to migrate. — IRTFM, Aug 23 '19 at 00:05
Ah, yes, if there is a way I can do that, I will be pleased to do so. Thank you. — Sylvia Rodriguez, Aug 23 '19 at 00:17

score 2 · Accepted Answer · answered Sep 12 '19 at 23:37

The methods "survdiff", "log-rank", "LR", "1" all give the same results.

Here is a minimal & reproducible example

library(survival)
library(survminer)

fit <- surv_fit(Surv(time, status) ~ sex, data = colon)

methods <- c("survdiff", "log-rank", "LR", "1")
purrr::imap(setNames(methods, methods), ~surv_pvalue(fit, method = .x))
#$survdiff
#  variable      pval   method pval.txt
#1      sex 0.6107936 Log-rank p = 0.61
#
#$`log-rank`
#  variable      pval   method pval.txt
#1      sex 0.6107936 Log-rank p = 0.61
#
#$LR
#  variable      pval   method pval.txt
#1      sex 0.6107936 Log-rank p = 0.61
#
#$`1`
#  variable      pval   method pval.txt
#1      sex 0.6107936 Log-rank p = 0.61

If we take a look at the source code of survminer we see that

[...]
allowed.methods <- c("survdiff", "log-rank", "LR", "1",
                       "n", "Gehan-Breslow", "GB",
                       "sqrtN", "Tarone-Ware", "TW",
                       "S1", "Peto-Peto", "PP",
                       "S2", "modified Peto-Peto", "mPP",
                       "FH_p=1_q=1", "Fleming-Harrington(p=1, q=1)", "FH")

method.names <- c(rep("survdiff", 4),
                rep(c("n", "sqrtN", "S1", "S2", "FH_p=1_q=1"), each = 3))
[...]

All four methods are unified as method.names = "survdiff".

Survminer, survival package: What is the difference between the "survdiff" log-rank and "regular" log-rank tests?

1 Answers1