I have data of 5794 subjects which were followed for 22 years, for a total of 18729 events (e.g., stroke, myocardial infarction, coronary heart disease death, etc). Additionally some of those subjects had ultrasound examinations at 5 and 11 years.
Let's say I want to study fatal strokes and limit the study to 5 years so that I can use ultrasound data at 5 years. Only 61 patients experienced fatal stroke. How should I treat all the other 5794 - 61 = 5733 subjects that didn't die from stroke or had other unrelated events ? Should I censor them or discard them ? How about the events ? I was thinking of filtering the 18729 events to take only whose with time_to_event <= 365.25 * 5 (or 11) but it seems kind of odd.
For example, subject XYZ might have had two non-fatal events and one fatal event (which is not stroke) before the fifth year. Another subject might have had only non-fatal events and still be alive at the fifth year, but again, no stroke.
I'm kind of lost since this isn't my area of expertise. Thank you for the help.
Edit:
There are two columns that are used to indicate time of censoring (CENSTIME
) and time to event (TTOEVENT
) from study entry (this is time = 0
). Additionally, there is another column, FATAL
that indicates whether an event is fatal (i.e., led to a death). If FATAL == 1
, CENSTIME
is equal to TTOEVENT
and is time of death; for each subject, in all events with FATAL == 0
, TTTOEVENT
indicates time to event and CENSTIME
indicates time of censoring. Finally, if a subject did not experience any event during the study, TTOEVENT
is NaN and CENSTIME
indicates time of censoring.
There is also a column that indicates event type EVTYPE
and has 12 different values:
- 0 - "No event"
- 1 - "MI"
- 2 - "Angina",
- 3 - "Stroke",
- 4 - "CHF",
- 5 - "Claudication",
- 6 - TIA",
- 7 - Angioplasty",
- 8 - Coronary Artery Bypass Surgery",
- 9 - Other Deaths (non-CHD)",
- 10 - ECG MI (silent)",
- 11 - other CHD Deaths"
Of these, 1, 3, 9 and 11 are potentially fatal (can lead to death).
time = 0
defined in your study? Is it the date of a diagnosis of some kind, or the date that an individual joined the study (perhaps at random), or just some calendar date that is common to all? Please provide that information by editing the question, as comments are easy to overlook and can be deleted. $\endgroup$