Examining the tests behind survival curves - Lex Jansen

Examining the tests behind survival curves

Presented by Hans-Dieter Spies at PhUSE, London 2014

? 2014 inVentiv Health. All rights reserved.

Survival Curves: Agenda

? Introduction ? Kaplan-Meier Method

> Kaplan-Meier Estimator > Example

? Log-Rank Test

> Log-Rank Statistic > Example

? Some Further Aspects ? Conclusion

2 ? 2014 inVentiv Health. All rights reserved.

Survival Curves: Introduction

Example: 2 Groups, each group has 5 subjects

Time to event group A group B

3

15

6 *

22

10

28

15

36

32 *

40

An * (asteriks) behind a number shows the time how long a subject without an event is under observation. These subjects are called censored.

3 ? 2014 inVentiv Health. All rights reserved.

Survival Curves: SAS Procedure PROC LIFETEST

The main theme of the PhUSE will focus on 'Data Transparency`. Here we will have a look what is behind PROC LIFETEST. And especially how to calculate the Log-rank test.

4 ? 2014 inVentiv Health. All rights reserved.

Survival Curves: Kaplan-Meier Estimator

PROC LIFETEST uses the Kaplan?Meier Estimator.

The Kaplan?0HLHU(VWLPDWRUW>6@LVGHILQHGDVDSURGXFW

W

ni - di ----------------

t(i) WQi

where

di = number of events, for which the event occurs at t(i) ni = number of events under risk at t(i)

5 ? 2014 inVentiv Health. All rights reserved.

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