Question: What should be reported as Hazard Ratio in Kaplan Meier curve?
1
gravatar for Raheleh
4 months ago by
Raheleh150
Raheleh150 wrote:

Hello all, I did survival analysis for my data and used log rank to test if there is significant difference between the high-risk and low-risk group. This my script and image:

k <- ggsurvplot(survfit(recsurv~T1_signature, data = MSKCC),
           data = MSKCC,
           risk.table = TRUE,
           pval = TRUE,
           conf.int = TRUE,
           ggtheme = theme_minimal(),
           risk.table.y.text.col = TRUE,
           risk.table.y.text = FALSE)

enter image description here

I want to add the HR in the graph as well. I did cox proportional hazards in R. This is the script:

hr <- coxph(recsurv~T1_signature, data = MSKCC)
summary(hr)

and this is the result:

Call:
coxph(formula = recsurv ~ T1_signature, data = MSKCC)

  n= 159, number of events= 6 

                    coef exp(coef) se(coef)      z Pr(>|z|)    
T1_signatureLow -2.89660   0.05521  0.87006 -3.329 0.000871 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

                exp(coef) exp(-coef) lower .95 upper .95
T1_signatureLow   0.05521      18.11   0.01003    0.3038

Concordance= 0.794  (se = 0.09 )
Likelihood ratio test= 11.17  on 1 df,   p=8e-04
Wald test            = 11.08  on 1 df,   p=9e-04
Score (logrank) test = 21.08  on 1 df,   p=4e-06

As far as I found out, for HR I need to subtract the amount of exp(coef) from 1 (1 – 0.05). In this case HR will be 0.95.

It means that the hazar ratio in my low-risk group decreased by 95%. Am I right? I want to use annotate to add HR in my plot. I am not sure should I report it as 0.05 0r 0.95?

I really appreciate any help!

ADD COMMENTlink modified 4 months ago by discombobulated10 • written 4 months ago by Raheleh150
0
gravatar for discombobulated
4 months ago by
discombobulated10 wrote:

Hi. Yes you are correct but you need to be careful in how you explain it. Your hazard ratio is 0.05 (ie 0.05:1) but you reduce your hazard by a factor of 95% (ie your hazard ratio as such hasn't decreased). It is only a nuance but it changes the meaning. I suggest reporting the hazard ratio (HR = 0.05 (95% C.I 0.01, 0.30)) in the graph and expand on this reporting a hazard reduction of 95% in text. also check your rounding :)

ADD COMMENTlink written 4 months ago by discombobulated10
0
gravatar for huynguyen96.dnu
4 months ago by
Vietnam
huynguyen96.dnu20 wrote:

Sorry, but I have a question on the interpretation of HR value. According to your above result, High is Reference and HR of Low is 0.06. So I will explain that Low is significantly associated with better outcome than High? Am I right?

ADD COMMENTlink written 4 months ago by huynguyen96.dnu20
0
gravatar for discombobulated
4 months ago by
discombobulated10 wrote:

looking at your output, low has been coded as 1 (your outcome) and high as 0 (the reference). So you are correct that the hazard ratio is reported for Low - i.e HR of Low is 0.06. As the HR is less than 1, Low has a hazard reduction. While it is often reported as risk, technically this is not correct. There are several papers on interpretation of survival analysis which may help you formulate the interpretation of your results. Have a look at these papers written for clinicians: https://journals.lww.com/anesthesia-analgesia/Fulltext/2018/09000/Survival_Analysis_and_Interpretation_of.32.aspx https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5388384/

ADD COMMENTlink written 4 months ago by discombobulated10
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