Search code examples
rsurvival-analysis

Not calculated median survival in Cox regression in R

mydat=structure(list(Biliary.Anast.Stricture = structure(c(1L, 1L, 
2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 
1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 
2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L), .Label = c("No", 
"Yes"), class = "factor"), TIME = c(98, 93, 11, 86, 69, 81, 50, 
34, 34, 46, 75, 77, 34, 54, 90, 90, 15, 90, 60, 13, 89, 83, 88, 
40, 0.2, 12, 7, 80, 65, 52, 81, 15, 66, 4, 82, 82, 67, 75, 82, 
68, 77, 79, 70, 76, 74, 71, 72, 13, 49, 59, 5, 44, 55, 71, 64, 
70, 62, 34, 72, 72, 26, 17, 59, 67, 50, 67, 14, 57, 33, 17, 62, 
59, 24, 55, 19, 4, 65, 67, 51, 62, 62, 26, 27, 64, 64, 30, 27, 
40, 49, 28, 60, 39, 4, 46, 17, 14, 59, 48, 52, 53, 37, 58, 42, 
56, 38, 46, 34, 52, 54, 53, 35, 16, 35, 3, 18, 51, 44, 33, 24, 
8, 39, 17, 13, 43, 46, 46, 46, 3, 17, 38, 25, 43, 17, 42, 26, 
41, 41, 14, 19, 29, 21, 28, 39, 21, 37, 28, 27, 38, 17, 32, 14, 
2, 35, 12, 35, 6, 22, 22, 22, 21, 13, 29, 22, 23, 7, 18, 27, 
22, 23, 19, 26, 25, 5, 12, 22, 14, 25, 24, 4, 16, 22, 18, 18, 
18, 16, 16, 16, 16, 16, 16, 15, 11, 14, 14, 13, 13, 13, 12, 11, 
12, 12, 11, 11, 11, 3, 10, 10), Censured.for.stricture. = structure(c(1L, 
1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 
2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
2L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 
1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L), .Label = c("censored", 
"COMPLETE"), class = "factor")), class = "data.frame", row.names = c(NA, 
-207L))

i do so

library("survival")
library("survminer")
> fit <- survfit(Surv(TIME, Censured.for.stricture.) ~ Biliary.Anast.Stricture,data=mydat)
> fit
Call: survfit(formula = Surv(TIME, Censured.for.stricture.) ~ Biliary.Anast.Stricture, 
    data = mydat)

and as you can see the median is not calculated like 0.95 CI

                              n events median 0.95LCL 0.95UCL
Biliary.Anast.Stricture=No  187      0     NA      NA      NA
Biliary.Anast.Stricture=Yes  20     20      5       4      11

How can i understand why median and CI are not calculated? I think my dataset has correct structure,but if i am wrong ,please suggest me what i should do!

Solution

  • You have no events (which means censored observations only) in No group.