Question 6 [10 marks) Consider a small hypothetical prospective cohort study of 50 subjects designed to study time to death. The maximum duration of follow-up was 15 years. A total of 12 subjects died during the study and an additional 12 subjects were loss to follow-up during the study. The remaining 26 subjects were alive after 15 years. Below are the death and loss times in years. Years of death 66 888 9 12 13 14 Years of loss to follow-up 33 44 5 6 7 88 9 11 13 (a) Fill in the missing values in the clinical life table below. Assume that censoring occurs uni- formly within each interval. You may use the space below and the reverse of this page for calculations but please put your answers in the table below. Carry out your calculations to 4 decimal places. [6 marks) 1 2 4 Alive at Start of Interval Died During Interval Withdrew During Interval uz Adjusted Number at Risk During Interval Cumulative Proportion Proportion Proportion who Died who Survived During Survived to End of Interval Interval Interval of ps Interval (1,1+n P+1 (0,5 (5,10 (10, 15] (b) In the context of this study, what is the interpretation of the final number in the P2+1 column? [1 mark] (c) Suppose instead of using a clinical life table you decide to use the Kaplan-Meier method of survival analysis. Complete the Kaplan-Meier table for the first three years of follow-up below. Carry out your calculations to 4 decimal places. [3 marks] ta d Wz 93 Pz P+1 Question 6 [10 marks) Consider a small hypothetical prospective cohort study of 50 subjects designed to study time to death. The maximum duration of follow-up was 15 years. A total of 12 subjects died during the study and an additional 12 subjects were loss to follow-up during the study. The remaining 26 subjects were alive after 15 years. Below are the death and loss times in years. Years of death 66 888 9 12 13 14 Years of loss to follow-up 33 44 5 6 7 88 9 11 13 (a) Fill in the missing values in the clinical life table below. Assume that censoring occurs uni- formly within each interval. You may use the space below and the reverse of this page for calculations but please put your answers in the table below. Carry out your calculations to 4 decimal places. [6 marks) 1 2 4 Alive at Start of Interval Died During Interval Withdrew During Interval uz Adjusted Number at Risk During Interval Cumulative Proportion Proportion Proportion who Died who Survived During Survived to End of Interval Interval Interval of ps Interval (1,1+n P+1 (0,5 (5,10 (10, 15] (b) In the context of this study, what is the interpretation of the final number in the P2+1 column? [1 mark] (c) Suppose instead of using a clinical life table you decide to use the Kaplan-Meier method of survival analysis. Complete the Kaplan-Meier table for the first three years of follow-up below. Carry out your calculations to 4 decimal places. [3 marks] ta d Wz 93 Pz P+1
