getEventProbabilities: Get Event Probabilities

In rpact: Confirmatory Adaptive Clinical Trial Design and Analysis

Get Event Probabilities

Description

Returns the event probabilities for specified parameters at given time vector.

Usage

getEventProbabilities(
  time,
  ...,
  accrualTime = c(0, 12),
  accrualIntensity = 0.1,
  accrualIntensityType = c("auto", "absolute", "relative"),
  kappa = 1,
  piecewiseSurvivalTime = NA_real_,
  lambda2 = NA_real_,
  lambda1 = NA_real_,
  allocationRatioPlanned = 1,
  hazardRatio = NA_real_,
  dropoutRate1 = 0,
  dropoutRate2 = 0,
  dropoutTime = 12,
  maxNumberOfSubjects = NA_real_
)

Arguments

time	A numeric vector with time values.
...	Ensures that all arguments (starting from the "...") are to be named and that a warning will be displayed if unknown arguments are passed.
accrualTime	The assumed accrual time intervals for the study, default is c(0, 12) (for details see getAccrualTime()).
accrualIntensity	A numeric vector of accrual intensities, default is the relative intensity 0.1 (for details see getAccrualTime()).
accrualIntensityType	A character value specifying the accrual intensity input type. Must be one of "auto", "absolute", or "relative"; default is "auto", i.e., if all values are < 1 the type is "relative", otherwise it is "absolute".
kappa	A numeric value > 0. A kappa != 1 will be used for the specification of the shape of the Weibull distribution. Default is 1, i.e., the exponential survival distribution is used instead of the Weibull distribution. Note that the Weibull distribution cannot be used for the piecewise definition of the survival time distribution, i.e., only piecewiselambda (as a single value) and kappa can be specified. This function is equivalent to pweibull(t, shape = kappa, scale = 1 / lambda) of the stats package, i.e., the scale parameter is 1 / 'hazard rate'. For example, getPiecewiseExponentialDistribution(time = 130, piecewiseLambda = 0.01, kappa = 4.2) and pweibull(q = 130, shape = 4.2, scale = 1 / 0.01) provide the sample result.
piecewiseSurvivalTime	A vector that specifies the time intervals for the piecewise definition of the exponential survival time cumulative distribution function (for details see getPiecewiseSurvivalTime()).
lambda2	The assumed hazard rate in the reference group, there is no default. lambda2 can also be used to define piecewise exponentially distributed survival times (see details). Must be a positive numeric of length 1.
lambda1	The assumed hazard rate in the treatment group, there is no default. lambda1 can also be used to define piecewise exponentially distributed survival times (see details). Must be a positive numeric of length 1.
allocationRatioPlanned	The planned allocation ratio n1 / n2 for a two treatment groups design, default is 1. If allocationRatioPlanned = 0 is entered, the optimal allocation ratio yielding the smallest overall sample size is determined.
hazardRatio	The vector of hazard ratios under consideration. If the event or hazard rates in both treatment groups are defined, the hazard ratio needs not to be specified as it is calculated, there is no default. Must be a positive numeric of length 1.
dropoutRate1	The assumed drop-out rate in the treatment group, default is 0.
dropoutRate2	The assumed drop-out rate in the control group, default is 0.
dropoutTime	The assumed time for drop-out rates in the control and the treatment group, default is 12.
maxNumberOfSubjects	If maxNumberOfSubjects > 0 is specified, the end of accrual at specified accrualIntensity for the specified number of subjects is determined or accrualIntensity is calculated at fixed end of accrual.

Details

The function computes the overall event probabilities in a two treatment groups design. For details of the parameters see getSampleSizeSurvival().

Value

Returns a EventProbabilities object. The following generics (R generic functions) are available for this result object:

• names() to obtain the field names,

• print() to print the object,

• summary() to display a summary of the object,

• plot() to plot the object,

• as.data.frame() to coerce the object to a data.frame,

• as.matrix() to coerce the object to a matrix.

How to get help for generic functions

Click on the link of a generic in the list above to go directly to the help documentation of the rpact specific implementation of the generic. Note that you can use the R function methods to get all the methods of a generic and to identify the object specific name of it, e.g., use methods("plot") to get all the methods for the plot generic. There you can find, e.g., plot.AnalysisResults and obtain the specific help documentation linked above by typing ?plot.AnalysisResults.

Examples

## Not run: 
# Calculate event probabilities for staggered subjects' entry, piecewisely defined
# survival time and hazards, and plot it.
timeVector <- seq(0, 100, 1)
y <- getEventProbabilities(timeVector, accrualTime = c(0, 20, 60), 
    accrualIntensity = c(5, 20), 
    piecewiseSurvivalTime = c(0, 20, 80),
    lambda2 = c(0.02, 0.06, 0.1), 
    hazardRatio = 2
)
plot(timeVector, y$cumulativeEventProbabilities, type = 'l')

## End(Not run)

rpact documentation built on Sept. 27, 2024, 5:08 p.m.