design_nb: Clinical trials with negative binomial outcomes

In gscounts: Group Sequential Designs with Negative Binomial Outcomes

Description

Design a clinical trial with negative binomial outcomes

Usage

design_nb(
  rate1,
  rate2,
  dispersion,
  power,
  ratio_H0 = 1,
  sig_level,
  random_ratio = 1,
  t_recruit1 = NULL,
  t_recruit2 = NULL,
  study_period = NULL,
  accrual_period = NULL,
  followup_max = NULL,
  accrual_speed = 1
)

Arguments

rate1	numeric; assumed rate of treatment group 1 in the alternative
rate2	numeric; assumed rate of treatment group 2 in the alternative
dispersion	numeric; dispersion (shape) parameter of negative binomial distribution
power	numeric; target power
ratio_H0	numeric; positive number denoting the rate ratio rate_1/rate_2 under the null hypothesis, i.e. the non-inferiority or superiority margin
sig_level	numeric; Type I error / significance level
random_ratio	numeric; randomization ratio n1/n2
t_recruit1	numeric vector; recruit (i.e. study entry) times in group 1
t_recruit2	numeric vector; recruit (i.e. study entry) times in group 2
study_period	numeric; study duration
accrual_period	numeric; accrual period
followup_max	numeric; maximum exposure time of a patient
accrual_speed	numeric; determines accrual speed; values larger than 1 result in accrual slower than linear; values between 0 and 1 result in accrual faster than linear.

Value

A list containing the following components:

rate1	as input
rate2	as input
dispersion	as input
power	as input
ratio_H0	as input
ratio_H1	ratio rate1/rate2
sig_level	as input
random_ratio	as input
t_recruit1	as input
t_recruit2	as input
study_period	as input
followup_max	as input
max_info	maximum information

Examples

# Calculate sample size for given accrual period and study duration assuming uniformal accrual
out <- design_nb(rate1 = 0.0875, rate2 = 0.125, dispersion = 5, power = 0.8,
                 ratio_H0 = 1, sig_level = 0.025,
                 study_period = 4, accrual_period = 1, random_ratio = 2)
out

# Calculate sample size for a fixed exposure time of 0.5 years
out <- design_nb(rate1 = 4.2, rate2 = 8.4, dispersion = 3, power = 0.8,
                 ratio_H0 = 1, sig_level = 0.025,
                 followup_max = 0.5, random_ratio = 2)
out

# Calculate study period for given recruitment time
t_recruit1 <- seq(0, 1.25, length.out = 1200)
t_recruit2 <- seq(0, 1.25, length.out = 800)
out <- design_nb(rate1 = 0.0875, rate2 = 0.125, dispersion = 5, power = 0.8,
                 ratio_H0 = 1, sig_level = 0.025,
                 t_recruit1 = t_recruit1, t_recruit2 = t_recruit2)

gscounts documentation built on Nov. 2, 2021, 9:07 a.m.