# How to interpret hazard ratio for continuous variable

#### pgseye

##### New Member
Hi,

I'm looking at survival curves for some data and wanting to see the effect of covariates in a Cox proportion hazards model, but am new to this and am not quite sure how to interpret some of the results.

I'm using R:

coxph(formula = Surv(Time.Months, status == 1) ~ Age.Months + var1 + var2)

n= 147

coef exp(coef) se(coef) z Pr(>|z|)
Age.Months -0.30079 0.74024 0.08248 -3.647 0.000265 ***
var1 0.99244 2.69780 0.46641 2.128 0.033354 *
var2 0.74730 2.11129 0.62832 1.189 0.234301
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

I'm interested primarily in the Age.Months variable which tells me at what age each individual had surgery (Time.Months is the time to secondary disease development following this surgery). var1 and var2 are binary variables.

How does one interpret the hazard ratio (0.74 in this case) for a continuous variable in this test?

Is saying something to the effect of "For each additional month waiting before undergoing surgery, there's approx a 26% reduction in the risk of developing secondary disease" a reasonable interpretation?

Thanks if anyone can help.

Paul