st: comparing 25th percentile survival time between two race groups

[Haena Lee <hannahlee419@gmail.com>]

Hi Listers,
I have tried to produce the median survival time and its 95% CI with
renal transplant data. "Stci" command, however, did not produce any
median values. So I generated the graph of median survival time by
race (African American vs. White) and the graph showed it only reached
to the length of 25% in the course of follow-up, indicating both of
groups have died not even near 50% (median), but mostly near the
length of 25% tile in the course of follow-up.

1. Given this, I attempted to produce 25th percentile survival time.
However I am struggling with comparing the difference of 25th
percentile survival time between African American and White across 10
regions in US. The command that I used:
sort UNOS
by UNOS: stci , by(race_all) p(25)

I was trying to use "ranksum" but it doesn't have an option for
testing differences of other percentiles besides median. Which command
should I use?

2. In comparing the median to the 25 percentile, there are some
regions where the length to 25% tile is significantly longer than
median. In this case, what would you guys do? If you would choose to
use median survival time, then what else could I do in order not only
to produce the median survival time and 95% CI, but to test the
difference of median survival time between groups instead stci (since
it didn't produce in previous analysis)?

Thank you so much!
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