Proportional hazards model

Abstract

This paper describes the proportional hazards mode. It was introduced as a statistical model for evaluation of censored cases which include cases lost to follow-up or those in which the event is not experienced before the study ends. Due to its easy applicability, it has become a common method for evaluating prognostic factors and the effects of treatment modes in many clinical studies. The proportional hazards model shows the contribution of prognostic factors adjusted for other factors by means of comparing the hazard ratio, not by a direct comparison of survival rates. In the first part of this paper, we introduce the concepts of the censored case, hazard and hazard ratio, which are the prognostic indicators of survival analysis, and later explain the proportional hazards model with an actual example.