Methods and Applications of Statistics in Clinical Trials, Volume 2: Planning, Analysis, and Inferential Methods

Chapter 20

Kaplan—Meier Plot

Norbert Holländer

20.1 Introduction

The Kaplan–Meier plot or Kaplan–Meier curve is the standard method to describe and compare graphically the overall survival of groups of patients. This method is applied to survival time, which is defined as time from treatment start or date of randomization to death or last date of follow-up, and, more general, to any type of time-to-event data, such as time-to-disease progression, time-to-deterioration, or time-to-first toxicity. Sometimes, the time-to-event is also called failure time. Below, the term “survival time” is used as a synonym for any time-to-event.

In addition to its broad applicability, the Kaplan–Meier plot has further advantages: It displays without bias nearly all information concerning survival time obtained in the data set. Furthermore, with the Kaplan–Meier plot, the outcome of a trial can easily be explained to clinicians. Therefore, the Kaplan–Meier plot is omnipresent in the clinical trials literature. No trial investigating survival time should be published without showing the curve.

The Kaplan–Meier plot is the graphical presentation of the nonparametric Kaplan–Meier estimator (K–M estimator) of the survival curve. The K–M estimator generalizes the empirical distribution function of a sample in the presence of censoring. Its name is derived from the seminal paper of E. L. Kaplan and P. Meier entitled “Non-parametric estimation from incomplete observations” in the Journal of the American ...