Incidence Density A cohort study (hypothetical) was conducted to look at surviva
ID: 3299549 • Letter: I
Question
Incidence Density
A cohort study (hypothetical) was conducted to look at survival after experiencing a myocardial infarction (heart attack). Ten participants were followed for 3 years, resulting in the following table:
Follow-up Time (Months)
Event
3
Death
5
Censored
8
Death
12
Death
17
Censored
19
Censored
27
Death
32
Censored
36
Followed until end of study period
36
Followed until end of study period
What is the cumulative survival probability at the end of the follow-up period? Censored is no data available, does not mean death)
(must show work)
Follow-up Time (Months)
Event
3
Death
5
Censored
8
Death
12
Death
17
Censored
19
Censored
27
Death
32
Censored
36
Followed until end of study period
36
Followed until end of study period
Explanation / Answer
Total number of deaths in 3 years = 4
Total participants = 10
So,
Total survived = 10 - 4 = 6
Hence,
Cumulative survival probability = 6/10 = 0.6