Is Kaplan-Meier Log-rank p-value valid even if one group has zero events


New Member
Hi all,

So first off, I am a novice so I apologize if this is a beginner question.

I am doing a research project where I am looking at immune sensitization prior to heart transplants and seeing if it has any bearing on outcomes after transplant. Patients fall into either a "Hi" or a "Lo" category based on an antibody panel.

One of the metrics I am looking at is mortality and I ran a Kaplan-Meier analysis and got a log-rank p-value of 0.024. Now, I only have events in the "Hi" category (5 deaths out of 17) and I have no events in the "Lo" category.

My question is: is the KM and the p-value I obtained still valid given the absence of events in the "Lo" group?

As a follow up question, in my patient population, I noticed a statistically significant difference in gender between the two groups. Can I run a survival analysis to see if there is a difference in mortality while accounting for gender?

Thanks so much in advance.