Tobias wrote:
I have the following problem: I want to plot patients'
survival from 0 to 5 (sts graph). I have only 5 patients
with follow-up of more than 5 years, so I want to restrict
the Kaplan-Meier curve to 5 years.
When I use the tmax(5) function, the curve ends at
approximately 4.5 years. This is the timepoint, when the
last patient with follow-up of less than 5 years was censored.
Is there a way to plot the curve exactly to 5 years?
Otherwise, it appears that the follow-up ends at 4.5 years.
----------------------------------------------------------------
I believe you hit an inconsistent Stata behavior. The following
gives a curve that ends at time 20:
clear
sysuse cancer
stset studytime , failure(died=1)
sts graph , tmax(20)
So does the following:
clear
sysuse cancer
drop if died==1 & studytime>19
stset studytime , failure(died=1)
sts graph , tmax(20)
But this one ends at time 19:
clear
sysuse cancer
drop if died==0 & studytime>19
stset studytime , failure(died=1)
sts graph , tmax(20)
So, apparently the time of the last censoring is considered
the end of information, even if events do occur later than that.
Until this inconsistency has been corrected: You might use
sts generate
to create coordinates for the graph. Hint: Points should
be connected "stairstep" with
... , connect(J)
See [G] connectstyle or -help connectstyle-
Hope this helps
Svend
________________________________________________________
Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6
DK-8000 Aarhus C, Denmark
Phone, work: +45 8942 6090
Phone, home: +45 8693 7796
Fax: +45 8613 1580
E-mail: [email protected]
_________________________________________________________
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