topic Re: How to interpret these results !! Hazard Ratio in ODS and Base Reporting

How to interpret these results !! Hazard Ratio

AminSaad — Fri, 24 Apr 2015 05:20:24 GMT

Parameter DF Parameter Standard Chi-Square Pr > ChiSq Hazard

Ratio Estimate Error

RF_CATEGORY 1 1 0.39888 0.54005 0.5455 0.4602 1.490 RF_CATEGORY 1

RF_CATEGORY 2 1 0.99090 0.52381 3.5785 0.0585 2.694 RF_CATEGORY 2

RF_CATEGORY 3 1 1.32557 0.55011 5.8063 0.0160 3.764 RF_CATEGORY 3

Effect DF Wald Chi-Square Pr > ChiSq

RF_CATEGORY 3 12.8814 0.0049

Hi everyone,

My background in statistic is not very solid. I have received this report and I'm not sure how to figure out whether the HR is significant or not? Could anyone explain. thanks.

Re: How to interpret these results !! Hazard Ratio

Ksharp — Fri, 24 Apr 2015 15:00:44 GMT

If I was right check Pr > ChiSq

if alpha=0.05 , then only the last one is significant .

Re: How to interpret these results !! Hazard Ratio

AminSaad — Fri, 24 Apr 2015 20:00:36 GMT

Ok I know this part about the 0.05, anything lower is statistically significant. What got me confused is the second table with the wald chi square ?? 0.0049 it reports this for only DF = 3,,, in other tables where the HR was significant for all there categories. I only got one p value for the wald chi-square? what does it signify?

Re: How to interpret these results !! Hazard Ratio

JacobSimonsen — Fri, 24 Apr 2015 20:07:18 GMT

The p-value of 0.0049 test the hypothesis that all three parameters are zero.

DF=3 because there are three less in a model where all the four Groups are equal (four Groups because there is also the reference Group).

Re: How to interpret these results !! Hazard Ratio

AminSaad — Fri, 24 Apr 2015 20:21:03 GMT

for the same variables I got the KM cureves. and there I have four curves with the reference and then I got this table? does that mean that the 3 curves are statistically different from the reference curve? and why do we have more that one test ?

test

chi square

pr>chisquare

Log-Rank

13.7304

0.0033

Wilcoxon

13.7798

0.0032

-2Log(LR)

13.8084

0.0032

Re: How to interpret these results !! Hazard Ratio

JacobSimonsen — Fri, 24 Apr 2015 20:48:30 GMT

When the wald test (or log-rank or -log(LR)) are significant it can be due to only one big contrast between two Groups, and not neccesaryly that all four Groups differ from each other. It is correct as you say that four Groups can not be assumed to be equal.

Proc phreg produce Wald, LogRank and -2Log(LR), they are asymptotic equivalent. You can write "type3(wald)" as option in the modelstatement if you only want the wald test.