survm_samplesize {survmixer}

Sample size calculation for mixture survival distributions

Description

The function 'survm_samplesize' calculates the sample size according to the distributional parameters of the responders and non-responders.

Usage

survm_samplesize(
  ascale0_r,
  ascale0_nr,
  ascale1_r,
  ascale1_nr,
  delta_p,
  p0,
  m0_r,
  m0_nr,
  diffm_r,
  diffm_nr,
  S0_r,
  S0_nr,
  diffS_r,
  diffS_nr,
  Delta_r,
  Delta_nr,
  ascale_cens,
  tau,
  bshape0 = 1,
  bshape1 = 1,
  all_ratio = 0.5,
  alpha = 0.025,
  beta = 0.2,
  set_param = 0
)

Arguments

ascale0_r

scale parameter for the Weibull distribution in the control group for responders

ascale0_nr

scale parameter for the Weibull distribution in the control group for non-responders

ascale1_r

scale parameter for the Weibull distribution in the intervention group for responders

ascale1_nr

scale parameter for the Weibull distribution in the intervention group for non-responders

delta_p

effect size for the response rate

p0

event rate for the response

m0_r

survival mean for responders in the control group

m0_nr

survival mean for non-responders in the control group

diffm_r

difference in survival means between groups for responders

diffm_nr

difference in survival means between groups for responders

S0_r

tau-year survival rates for responders in the control group

S0_nr

tau-year survival rates for non-responders in the control group

diffS_r

difference in tau-year survival rates for responders

diffS_nr

difference in tau-year survival rates for non-responders

Delta_r

restricted mean survival times (RMST) difference between intervention and control groups for responders

Delta_nr

RMST difference between intervention and control groups for non-responders

ascale_cens

distributional parameter for the exponential distribution for the censoring

tau

follow-up

bshape0

shape parameter for the Weibull distribution in the control group

bshape1

shape parameter for the Weibull distribution in the intervention group

all_ratio

allocation ratio. The ratio of numbers of participants allocated in the control group. By default is assumed 1:1 (i.e., all_ratio=0.5)

alpha

type I error

beta

type II error

set_param

Set of parameters to be used for the responders/non-responders survival functions If the set of parameters is =1, then the sample size is computed using the survival means (m0_r,m0_nr,diffm _r,diffm_nr); if set_param=2, it is computed using the tau-year survival rates (S0_r,S0_nr,diffS_r,diffS_nr); if set_param=2, it is computed using the RMSTs and survival rates (Delta_r,Delta_nr,S0_r,S0_nr). If set_param=0, the computation is based on the distributional parameters (ascale0_r, ascale0_nr, ascale1_r, ascale1_nr).

Value

This function returns the total sample size needed and the expected effect size for overall survival (RMST difference between groups).

Author(s)

Marta Bofill Roig.

References

Design of phase III trials with long-term survival outcomes based on short-term binary results. Marta Bofill Roig, Yu Shen, Guadalupe Gomez Melis. arXiv:2008.12887