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st: RE: Relative survival - strel
From
Nick Cox <[email protected]>
To
"'[email protected]'" <[email protected]>
Subject
st: RE: Relative survival - strel
Date
Thu, 6 Oct 2011 11:39:14 +0100
As -strel- is not found by -findit-, it is especially important to explain to those curious where it comes from.
Nick
[email protected]
Sam Leary
I am a bit of a novice at survival analysis, but am trying to
calculate relative survival using strel. My variables are
death_5y = 1 if died by 5 years after diagnosis, 0 if still alive at 5 years
age_diag = age at diagnosis (years)
age_death = age at death or 5 years, whichever came first (years)
I have downloaded a lifetable which has the following variables:
country calendar_year sex age rate
and I have only kept the data for the calendar year relating to the start
date of my audit. I have also sorted this file by age then sex.
So I have used the following commands to calculate the crude and relative
survival at 5 years after diagnosis:
stset age_death, failure(death_5y) origin(age_diag)
strel 0 5 using "ltab_s1",mergeby(sex)
My question is, as there are 257 deaths out of a total of 468, why is the
crude survival percentage 41.86 using strel, rather than (468-257)/468 =
45.1?
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