rmpower1s: Power for One-Sample Restricted Mean Survival Time

In lrstat: Power and Sample Size Calculation for Non-Proportional Hazards and Beyond

Power for One-Sample Restricted Mean Survival Time

Description

Estimates the power, stopping probabilities, and expected sample size in a one-group survival design.

Usage

rmpower1s(
  kMax = 1L,
  informationRates = NA_real_,
  efficacyStopping = NA_integer_,
  futilityStopping = NA_integer_,
  criticalValues = NA_real_,
  alpha = 0.025,
  typeAlphaSpending = "sfOF",
  parameterAlphaSpending = NA_real_,
  userAlphaSpending = NA_real_,
  futilityBounds = NA_real_,
  typeBetaSpending = "none",
  parameterBetaSpending = NA_real_,
  milestone = NA_real_,
  rmstH0 = NA_real_,
  accrualTime = 0L,
  accrualIntensity = NA_real_,
  piecewiseSurvivalTime = 0L,
  stratumFraction = 1L,
  lambda = NA_real_,
  gamma = 0L,
  accrualDuration = NA_real_,
  followupTime = NA_real_,
  fixedFollowup = 0L,
  spendingTime = NA_real_,
  studyDuration = NA_real_
)

Arguments

kMax	The maximum number of stages.
informationRates	The information rates. Defaults to (1:kMax) / kMax if left unspecified.
efficacyStopping	Indicators of whether efficacy stopping is allowed at each stage. Defaults to true if left unspecified.
futilityStopping	Indicators of whether futility stopping is allowed at each stage. Defaults to true if left unspecified.
criticalValues	Upper boundaries on the z-test statistic scale for stopping for efficacy.
alpha	The significance level. Defaults to 0.025.
typeAlphaSpending	The type of alpha spending. One of the following: "OF" for O'Brien-Fleming boundaries, "P" for Pocock boundaries, "WT" for Wang & Tsiatis boundaries, "sfOF" for O'Brien-Fleming type spending function, "sfP" for Pocock type spending function, "sfKD" for Kim & DeMets spending function, "sfHSD" for Hwang, Shi & DeCani spending function, "user" for user defined spending, and "none" for no early efficacy stopping. Defaults to "sfOF".
parameterAlphaSpending	The parameter value for the alpha spending. Corresponds to Delta for "WT", rho for "sfKD", and gamma for "sfHSD".
userAlphaSpending	The user defined alpha spending. Cumulative alpha spent up to each stage.
futilityBounds	Lower boundaries on the z-test statistic scale for stopping for futility at stages 1, ..., kMax-1. Defaults to rep(-6, kMax-1) if left unspecified. The futility bounds are non-binding for the calculation of critical values.
typeBetaSpending	The type of beta spending. One of the following: "sfOF" for O'Brien-Fleming type spending function, "sfP" for Pocock type spending function, "sfKD" for Kim & DeMets spending function, "sfHSD" for Hwang, Shi & DeCani spending function, and "none" for no early futility stopping. Defaults to "none".
parameterBetaSpending	The parameter value for the beta spending. Corresponds to rho for "sfKD", and gamma for "sfHSD".
milestone	The milestone time at which to calculate the restricted mean survival time.
rmstH0	The restricted mean survival time under the null hypothesis.
accrualTime	A vector that specifies the starting time of piecewise Poisson enrollment time intervals. Must start with 0, e.g., c(0, 3) breaks the time axis into 2 accrual intervals: [0, 3) and [3, Inf).
accrualIntensity	A vector of accrual intensities. One for each accrual time interval.
piecewiseSurvivalTime	A vector that specifies the starting time of piecewise exponential survival time intervals. Must start with 0, e.g., c(0, 6) breaks the time axis into 2 event intervals: [0, 6) and [6, Inf). Defaults to 0 for exponential distribution.
stratumFraction	A vector of stratum fractions that sum to 1. Defaults to 1 for no stratification.
lambda	A vector of hazard rates for the event in each analysis time interval by stratum under the alternative hypothesis.
gamma	The hazard rate for exponential dropout or a vector of hazard rates for piecewise exponential dropout. Defaults to 0 for no dropout.
accrualDuration	Duration of the enrollment period.
followupTime	Follow-up time for the last enrolled subject.
fixedFollowup	Whether a fixed follow-up design is used. Defaults to 0 for variable follow-up.
spendingTime	A vector of length kMax for the error spending time at each analysis. Defaults to missing, in which case, it is the same as informationRates.
studyDuration	Study duration for fixed follow-up design. Defaults to missing, which is to be replaced with the sum of accrualDuration and followupTime. If provided, the value is allowed to be less than the sum of accrualDuration and followupTime.

Value

An S3 class rmpower1s object with 3 components:

• overallResults: A data frame containing the following variables:

  • overallReject: The overall rejection probability.

  • alpha: The overall significance level.

  • drift: The drift parameter, equal to (rmst - rmstH0)*sqrt(information).

  • inflationFactor: The inflation factor (relative to the fixed design).

  • numbeOfSubjects: The total number of subjects.

  • studyDuration: The total study duration.

  • information: The maximum information.

  • expectedNumberOfSubjects: The expected number of subjects.

  • expectedStudyDuration: The expected study duration.

  • expectedInformation: The expected information.

  • accrualDuration: The accrual duration.

  • followupTime: The follow-up duration.

  • fixedFollowup: Whether a fixed follow-up design is used.

  • kMax: The number of stages.

  • milestone: The milestone time relative to randomization.

  • rmstH0: The restricted mean survival time under the null hypothesis.

  • rmst: The restricted mean survival time under the alternative hypothesis.

• byStageResults: A data frame containing the following variables:

  • informationRates: The information rates.

  • efficacyBounds: The efficacy boundaries on the Z-scale.

  • futilityBounds: The futility boundaries on the Z-scale.

  • rejectPerStage: The probability for efficacy stopping.

  • futilityPerStage: The probability for futility stopping.

  • cumulativeRejection: The cumulative probability for efficacy stopping.

  • cumulativeFutility: The cumulative probability for futility stopping.

  • cumulativeAlphaSpent: The cumulative alpha spent.

  • numberOfSubjects: The number of subjects.

  • analysisTime: The average time since trial start.

  • efficacyRmst: The efficacy boundaries on the restricted mean survival time.

  • futilityRmst: The futility boundaries on the restricted mean survival time.

  • efficacyP: The efficacy boundaries on the p-value scale.

  • futilityP: The futility boundaries on the p-value scale.

  • information: The cumulative information.

  • efficacyStopping: Whether to allow efficacy stopping.

  • futilityStopping: Whether to allow futility stopping.

• settings: A list containing the following input parameters: typeAlphaSpending, parameterAlphaSpending, userAlphaSpending, typeBetaSpending, parameterBetaSpending, accrualTime, accuralIntensity, piecewiseSurvivalTime, stratumFraction, lambda, gamma, and spendingTime.

Author(s)

Kaifeng Lu, [e-mail]

See Also

rmstat

Examples

rmpower1s(kMax = 2, informationRates = c(0.8, 1),
          alpha = 0.025, typeAlphaSpending = "sfOF",
          milestone = 18, rmstH0 = 10,
          accrualTime = seq(0, 8),
          accrualIntensity = 26/9*seq(1, 9),
          piecewiseSurvivalTime = c(0, 6),
          stratumFraction = c(0.2, 0.8),
          lambda = c(0.0533, 0.0309, 1.5*0.0533, 1.5*0.0309),
          gamma = -log(1-0.05)/12, accrualDuration = 22,
          followupTime = 18, fixedFollowup = FALSE)

lrstat documentation built on Oct. 18, 2024, 9:06 a.m.