8.14 Comparing survival probabilities

  • It is frequently of great interest whether groups of patients have the same survival probabilities.

  • In this graph, the survival curve for men and women are compared.

# plot survival curve for men and women
sfit <- survfit(Surv(time, status) ~  sex, data=lung)
ggsurvplot(sfit, 
           conf.int=TRUE, 
           pval=TRUE,
           legend.labs=c("Male", "Female"), 
           legend.title="Sex",  
           palette=c("cornflowerblue", "indianred3"), 
           title="Kaplan-Meier Curve for lung cancer survival",
           xlab = "Time (days)")

  • A couple ggsurvplot options: (1) conf.int provides confidence intervals, (2) pval provides a log-rank test comparing the survival curves.

  • The p-value (0.0013) provides strong evidence that men and women have different survival probabilities following treatment.