Introduction to Survival Analysis

Abstract

What is Survival Analysis?

In many clinical situations, we are interested not only in studying whether an event occurs, but also in deter-mining at what point it take place during the follow-up.

Survival analysis is a set of statistical procedures for data analysis in which the outcome variable is the time until an event occurs.

What Is It for?

The first applications of this analysis studied the time from the start of treatment to death, hence the name “survival”. Subsequently, it was extended to other situations of clinical interest (time to readmission, treatment abandonment, return to work after surgery, etc.), so that a more appropriate name is time-to-event analysis.

The objectives of survival analysis are: a) to estimate and interpret survival, b) to compare survival between different groups, and c) to evaluate the relationship of different explanatory variables with survival.¹