Timevar for survival analysis

[Carlotta Jarach]

Dear All,

This might be a silly question, but it is driving me crazy.

I am managing data which were not recorded for survival analysis and I am trying to put them in a proper format.

For the purpose of my question, here my data (I have more variables, but they behave as Var1 and Var2, namely varying during time):

ID	Visit	Date	DOsp1	DOsp2	Sex	Var1	Var2
1	0	1mar2002			M	0	.
1	1	3jun2005			M	.	.
1	2	4feb2007			M	.	.
2	0	9feb2002	21dec2000	22jun2001	F	1	18.9
2	1	7sep2002			F	2	9999
3	0	25mar2003			M	0	20
3	1	13oct2004			M	2	9999
4	0	4oct2002			F	1	23.5
4	1	03may2004	4jan2003	24jun2003	F	.	.
4	2	13jan2006			F	.	.
4	3	25aug2007			F	2	9999

ID is my person identifier, who can be visited several times (Visit, 0 is the baseline) in different dates (Date is when the visit took place). Each person, during the visit, could say up to 9 dates (I do have DOsp1-DOsp9, but for the sake of this question I just put the first two) regarding if and when they were hospitalized between the visits.

I will use snapspan in order to convert my data to time-span data, but before I guess I need to slightly change my time variable (and the dataset overall).

I want to have a timevar like Time (see table below) in order to run snapspan ID Time.

ID	Visit	Date	DOsp1	DOsp2	Sex	Var1	Var2	Time
1	0	1mar2002			M	0	.	1mar2002
1	1	3jun2005			M	.	.	3jun2005
1	2	4feb2007			M	.	.	4feb2007
2	.	.	.	.	.	.	.	21dec2000
2	.	.	.	.	.	.	.	22jun2001
2	0	9feb2002	21dec2000	22jun2001	F	1	18.9	9feb2002
2	1	7sep2002			F	2	9999	7sep2002
3	0	25mar2003			M	0	20	25mar2003
3	1	13oct2004			M	2	9999	13oct2004
4	0	4oct2002			F	1	23.5	4oct2002
4	.	.	.	.	.	.	.	4jan2003
4	.	.	.	.	.	.	.	24jun2003
4	1	03may2004	4jan2003	24jun2003	F	.	.	03may2004
4	2	13jan2006			F	.	.	13jan2006
4	3	25aug2007			F	2	9999	25aug2007

This is the final dataset I want to obtain:

ID	Datestarts	Dateends	Sex	Var1	Var2	Event	Event_recode
1	.	1mar2002	M	0	.	Visit 0	0
1	1mar2002	3jun2005	M	.	.	Visit 1	0
1	3jun2005	4feb2007	M	.	.	Visit 2	0
2	.	9feb2002	F	1	18.9	Visit 0	0
2	9feb2002	7sep2002	F	2	9999	Visit 1	2
3	.	25mar2003	M	0	20	Visit 0	0
3	25mar2003	13oct2004	M	2	9999	Visit 1	2
4	.	4oct2002	F	1	23.5	Visit 0	0
4	4oct2002	4jan2003	F	.	.	Osp 1	1
4	4jan2003	24jun2003	F	.	.	Osp 2	1
4	24jun2003	03may2004	F	.	.	Visit 1	0
4	03may2004	13jan2006	F	.	.	Visit 2	0
4	13jan2006	25aug2007	F	2	9999	Visit 3	2

As you might notice, if any date recorded in DOsp1-DOsp9 happened before Visit 0, it will not be taken into account. Then Event_recode will be build in order to have the failure var for my stset (Event_recode will be 0 if the row is regarding a visit, 1 if it is regarding an hospitalization, 2 if the person dies, namely if Var1==2, and then 3 if it is censored).

All of that, in order to run the following code:

stset Dataends, id(ID) time0( Datastarts ) origin(time Datastarts ) failure(Event_recode==1 2 ).

Thank you to anyone who can help me, feel free to ask me clarifications.
Best