natrisk: Number of subjects at risk

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

Number of subjects at risk

Description

Obtains the number of subjects at risk at given analysis times for each treatment group.

Usage

natrisk(
  time = NA_real_,
  allocationRatioPlanned = 1,
  accrualTime = 0L,
  accrualIntensity = NA_real_,
  piecewiseSurvivalTime = 0L,
  lambda1 = NA_real_,
  lambda2 = NA_real_,
  gamma1 = 0L,
  gamma2 = 0L,
  accrualDuration = NA_real_,
  minFollowupTime = NA_real_,
  maxFollowupTime = NA_real_
)

Arguments

time	A vector of analysis times at which to calculate the number of patients at risk.
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.
minFollowupTime	Follow-up time for the last enrolled subject.
maxFollowupTime	Follow-up time for the first enrolled subject. For fixed followup, maxFollowupTime = minFollowupTime. For variable followup, maxFollowupTime = accrualDuration + minFollowupTime.

Value

A matrix of the number of patients at risk at the specified analysis times (row) for each treatment group (column).

Author(s)

Kaifeng Lu, [e-mail]

Examples

# Piecewise accrual, piecewise exponential survivals, and 5% dropout by
# the end of 1 year.

natrisk(time = c(9, 24), 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, minFollowupTime = 18,
        maxFollowupTime = 30)

lrstat documentation built on June 23, 2024, 5:06 p.m.