Week 8 Problems—30 points
15 points each. Place answers within the Word document below.
1. A study is conducted to estimate survival in patients following kidney transplant. Key factors that adversely affect success of the transplant include advanced age and diabetes. This study involves 25 participants who are 65 years of age and older and all have diabetes. Following transplant, each participant is followed for up to 10 years. The following are times to death, in years, or the time to last contact (at which time the participant was known to be alive).
Deaths: 1.2, 2.5, 4.3, 5.6, 6.7, 7.3 and 8.1 years
Alive: 3.4, 4.1, 4.2, 5.7, 5.9, 6.3, 6.4, 6.5, 7.3, 8.2, 8.6, 8.9, 9.4, 9.5, 10, 10, 10, and 10 years
Use the life table approach to estimate the survival function. Use years intervals of
0–2; 2–4;
Complete the table below.
| Interval
in Years |
Number At Risk During Interval,
Nt |
Average Number At Risk During Interval,
Nt* =Nt-Ct /2 |
Number of Deaths During Interval,
Dt |
Lost to Follow-Up,
Ct |
Proportion Dying
qt = Dt/Nt* |
Proportion Surviving
pt = 1-qt
|
Survival Probability
St = pt*St-1 |
| 0–2 | |||||||
| 2–4 | |||||||
| 4–6 | |||||||
| 6–8 | |||||||
| 8–10 |
Use the Kaplan-Meier approach to estimate the survival function.
Complete the table below
| Time, Years | Number at Risk
Nt |
Number of Deaths
Dt |
Number Censored
Ct |
Survival Probability
St+1= St*((Nt-Dt)/Nt) |
| 0 | 25 | |||
| 1.2 | ||||
| 2.5 | ||||
| 3.4 | ||||
| 4.1 | ||||
| 4.2 | ||||
| 4.3 | ||||
| 5.6 | ||||
| 5.7 | ||||
| 5.9 | ||||
| 6.3 | ||||
| 6.4 | ||||
| 6.5 | ||||
| 6.7 | ||||
| 7.3 | ||||
| 8.1 | ||||
| 8.2 | ||||
| 8.6 | ||||
| 8.9 | ||||
| 9.4 | ||||
| 9.5 | ||||
| 10.0 |
