covrmst {lrstat}

Covariance between restricted mean survival times

Description

Obtains the covariance between restricted mean survival times at two different time points.

Usage

covrmst(
  t2 = NA_real_,
  tau1 = NA_real_,
  tau2 = NA_real_,
  allocationRatioPlanned = 1,
  accrualTime = 0L,
  accrualIntensity = NA_real_,
  piecewiseSurvivalTime = 0L,
  lambda1 = NA_real_,
  lambda2 = NA_real_,
  gamma1 = 0L,
  gamma2 = 0L,
  accrualDuration = NA_real_,
  maxFollowupTime = NA_real_
)

Arguments

t2

The calendar time for analysis 2.

tau1

The milestone time for analysis 1.

tau2

The milestone time for analysis 2.

allocationRatioPlanned

Allocation ratio for the active treatment versus control. Defaults to 1 for equal randomization.

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.

lambda1

A vector of hazard rates for the event for the active treatment group. One for each analysis time interval.

lambda2

A vector of hazard rates for the event for the control group. One for each analysis time interval.

gamma1

The hazard rate for exponential dropout, or a vector of hazard rates for piecewise exponential dropout for the active treatment group.

gamma2

The hazard rate for exponential dropout, or a vector of hazard rates for piecewise exponential dropout for the control group.

accrualDuration

Duration of the enrollment period.

maxFollowupTime

Follow-up time for the first enrolled subject. For fixed followup, maxFollowupTime = minFollowupTime. For variable followup, maxFollowupTime = accrualDuration + minFollowupTime.

Value

The covariance between the restricted mean survival times for each treatment group.

Author(s)

Kaifeng Lu, [e-mail]

Examples

covrmst(t2 = 25, tau1 = 16, tau2 = 18, allocationRatioPlanned = 1,
        accrualTime = c(0, 3), accrualIntensity = c(10, 20),
        piecewiseSurvivalTime = c(0, 6),
        lambda1 = c(0.0533, 0.0309), lambda2 = c(0.0533, 0.0533),
        gamma1 = -log(1-0.05)/12, gamma2 = -log(1-0.05)/12,
        accrualDuration = 12, maxFollowupTime = 30)