KM plot from different public datasets

Question

[rob.costa1234]

I have 4 different data sets of same disease with No of days of survival and death. I want to correlate this data with gene expression of my study. Can I used 4 different data sets based on high and low expression of my genes and survival and death in each datsets and club them together for presentation and drive a hypothesis. Is there something particular I need to pay attention? The number of samples are very small in each data sets, Idea is pooling will provide better analysis.

Thanks

[Kevin Blighe]

Are the study designs matched?