Docetaxel with prednisone or prednisolone for the treatment of ...

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Appendix 5
Step 4. Calculate HR
HR = exp[ln(HR)]
= exp(0.052094) = 1.053474
Step 5. Calculate the variance of ln(HR),
var[ln(HR)]:
var[ln(HR)] = 1/V
Var[ln(HR)] = 1/31.5 = 0.0317
Step 6. Calculate the 95% CI for HR:
95% CI = exp{ln(HR) ± 1.96 × √ –––––––––––
var[ln(HR)]}
95% CI = exp[0.052094 ± 1.96 × √ –––––––
0.0317]
95% CI = 0.747 to 1.494
Therefore, the HR for death in this example is
1.05 (95% CI: 0.747 to 1.494).