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Table 5 Calibration by risk group

From: External validation of a Cox prognostic model: principles and methods

Risk group t Kaplan-Meier Predicted
  (yr) Derivation Validation Validation
   N Ev. S ̂ (t) SE N Ev. S ̂ (t) SE S ¯ (t)
1. Good 2 247 90 0.90 0.02 124 28 0.88 0.03 0.88
  5    0.71 0.03    0.68 0.05 0.73
2. Fairly good 2 526 270 0.82 0.02 277 103 0.85 0.02 0.78
  5    0.56 0.02    0.59 0.03 0.54
3. Fairly poor 2 526 401 0.60 0.02 225 123 0.61 0.03 0.63
  5    0.31 0.02    0.37 0.04 0.32
4. Poor 2 247 204 0.44 0.03 60 45 0.53 0.07 0.47
  5    0.20 0.03    0.11 0.05 0.16
  1. Values shown are Kaplan-Meier estimates and standard errors of recurrence-free survival probabilties in the three groups at two times. Values labelled Predicted were predicted from the derivation dataset by applying the PI to the smooth baseline survival estimate at the individual level in the validation dataset, and averaging across each risk group. N and Ev. denote the number of patients and events in each group.