gs.boundaries.fut: Computes group sequential boundaries with futility stopping

In SurrogateSeq: Group Sequential Testing of a Treatment Effect Using a Surrogate Marker

Computes group sequential boundaries with futility stopping

Description

Computes group sequential (and naive) boundaries for the nonparametric test for a treatment effect on the primary outcome using surrogate marker information. The boundaries and test statistic borrow information from a prior study (Study A) about the relationship between the surrogate and the primary outcome to test for a treatment effect in the current study (Study B). The group sequential boundaries allow for futility stopping (bounds given).

Usage

gs.boundaries.fut(szerop, sonep, yzerop, nzero, none, n.stg, B.norm = 1e+06, 
alpha = 0.05, pp = 0.4, inf.fraction = (1:n.stg)/n.stg, j.star=1, 
alpha0=(j.star/n.stg)*alpha, 
plot = FALSE)

Arguments

szerop	surrogate marker in the control group in Study A
sonep	surrogate marker in the treated group in Study A
yzerop	primary outcome in the control group in Study A
nzero	sample size of control group in Study B
none	sample size of treated group in Study B
n.stg	maximum number of analyses
B.norm	number of multivariate normal vectors to use in simulation for boundaries; default is 1e+06
alpha	desired rejection probability of the test; default is 0.05
pp	power parameter for Wang-Tsiatis boundaries; default is 0.4
inf.fraction	information fraction vector of the same length as n.stg which reflects the fraction of information at each analysis, should be positive, non-decreasing, and the last entry should be 1; default is (1:n.stg)/n.stg, user may want to specify a different vector for unequal time points
j.star	earliest stage at which futility stopping is allowed. Should be <= n.stg-1 (there is already "futility stopping" at the n.stg-th stage anyway). Default is 1.
alpha0	the part of alpha that c1 is chosen to spend in first j.star stages; default is (j.star/n.stg)*alpha
plot	TRUE or FALSE if a plot of the boundaries is desired; default is FALSE

Value

Returns a list of boundaries:

Naive	Naive boundaries
Bonf	Bonferroni boundaries
Pocock.futility	Pocock futility boundaries
Pocock.nullrejection	Pocock null rejection boundaries
OBrien_Fleming.futility	O'Brien-Fleming futility boundaries
OBrien_Fleming.nullrejection	O'Brien-Fleming null rejection boundaries
Wang_Tsiatis.futility	Wang-Tsiatis futility boundaries
Wang_Tsiatis.nullrejection	Wang-Tsiatis null rejection boundaries

Author(s)

Layla Parast and Jay Bartroff

References

Parast and Bartroff (2024). Group sequential testing of a treatment effect using a surrogate marker. Biometrics, 80(4), ujae108.

Examples

data(example.data)
data(StudyA.aids)
data(StudyB.aids)
s0.studya = StudyA.aids$s0
s1.studya = StudyA.aids$s1


bound = gs.boundaries.fut(szerop = s0.studya, sonep = s1.studya, yzerop=StudyA.aids$y0, 
nzero = nrow(StudyB.aids$s0),none = nrow(StudyB.aids$s1), n.stg=4, B.norm=1e6, 
alpha=0.05)

bound

SurrogateSeq documentation built on April 4, 2025, 12:27 a.m.