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Freireich 6-MP leukaemia remission times: Kaplan-Meier survival with Greenwood standard errors

ToolWeibull Life Analysis
SourceFreireich, E. J., Gehan, E., Frei, E., et al. (1963). "The Effect of 6-Mercaptopurine on the Duration of Steroid-Induced Remissions in Acute Leukemia." Blood, Vol. 21, No. 6, pp. 699–716; as tabulated in Cox, D. R., and Oakes, D. (1984). Analysis of Survival Data. Chapman and Hall, London. Table 1.1.
LevelGraduate

Problem

Twenty-one leukaemia patients treated with 6-mercaptopurine were followed for the length of remission in weeks; nine relapsed and twelve were still in remission at the end of the study. Estimate the survival (remission) function by the Kaplan-Meier product limit at each relapse time and its Greenwood standard error.

Inputs to Enter

  • Relapses (failures): 6 F 3; 7 F; 10 F; 13 F; 16 F; 22 F; 23 F
  • Still in remission (suspensions): 6 S; 9 S; 10 S; 11 S; 17 S; 19 S; 20 S; 25 S; 32 S 2; 34 S; 35 S
  • Time unit weeks; the Kaplan-Meier table and curve appear with any primary method
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Answers

  • At risk 21 at t = 6 and 17 at t = 7
  • Ŝ(6) = 0.857, Ŝ(7) = 0.807, Ŝ(10) = 0.753, Ŝ(13) = 0.690, Ŝ(16) = 0.627, Ŝ(22) = 0.538, Ŝ(23) = 0.448
  • Greenwood SE at t = 6: 0.857 √(3/(21 · 18)) = 0.0764; at t = 23: 0.1346 (R survfit)

Notes

Paste the 18 lines (counts as trailing integers). The data are the R MASS package's gehan set, 6-MP group (References/Weibull/Data/). Survival values reproduced to 5e-4 (test_weibull.php).

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