getAccrualTime {rpact} | R Documentation |
Returns an AccrualTime
object that contains the accrual time and the accrual intensity.
getAccrualTime( accrualTime = NA_real_, ..., accrualIntensity = NA_real_, maxNumberOfSubjects = NA_real_ )
accrualTime |
The assumed accrual time for the study, default is |
... |
Ensures that all arguments (starting from the "...") are to be named and that a warning will be displayed if unknown arguments are passed. |
accrualIntensity |
A value or vector of accrual intensities, default is the relative
intensity |
maxNumberOfSubjects |
The maximum number of subjects. |
Returns an AccrualTime
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
,
accrualTime
is the time period of subjects' accrual in a study.
It can be a value that defines the end of accrual or a vector.
In this case, accrualTime
can be used to define a non-constant accrual over time.
For this, accrualTime
is a vector that defines the accrual intervals.
The first element of accrualTime
must be equal to 0
and, additionally,
accrualIntensity
needs to be specified.
accrualIntensity
itself is a value or a vector (depending on the
length of accrualtime
) that defines the intensity how subjects
enter the trial in the intervals defined through accrualTime
.
accrualTime
can also be a list that combines the definition of the accrual time and
accrual intensity (see below and examples for details).
If the length of accrualTime
and the length of accrualIntensity
are the same
(i.e., the end of accrual is undefined), maxNumberOfSubjects > 0
needs to be specified
and the end of accrual is calculated.
In that case, accrualIntensity
is the number of subjects per time unit, i.e., the absolute accrual intensity.
If the length of accrualTime
equals the length of accrualIntensity - 1
(i.e., the end of accrual is defined), maxNumberOfSubjects
is calculated if the absolute accrual intensity is given.
If all elements in accrualIntensity
are smaller than 1, accrualIntensity
defines
the *relative* intensity how subjects enter the trial.
For example, accrualIntensity = c(0.1, 0.2)
specifies that in the second accrual interval
the intensity is doubled as compared to the first accrual interval. The actual (absolute) accrual intensity
is calculated for the calculated or given maxNumberOfSubjects
.
Note that the default is accrualIntensity = 0.1
meaning that the *absolute* accrual intensity
will be calculated.
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
.
getNumberOfSubjects
for calculating the number of subjects at given time points.
# Assume that in a trial the accrual after the first 6 months is doubled # and the total accrual time is 30 months. # Further assume that a total of 1000 subjects are entered in the trial. # The number of subjects to be accrued in the first 6 months and afterwards # is achieved through getAccrualTime(accrualTime = c(0, 6, 30), accrualIntensity = c(0.1, 0.2), maxNumberOfSubjects = 1000) # The same result is obtained via the list based definition getAccrualTime(list( "0 - <6" = 0.1, "6 - <=30" = 0.2), maxNumberOfSubjects = 1000) # Calculate the end of accrual at given absolute intensity: getAccrualTime(accrualTime = c(0, 6), accrualIntensity = c(18, 36), maxNumberOfSubjects = 1000) # Via the list based definition this is getAccrualTime(list( "0 - <6" = 18, ">=6" = 36), maxNumberOfSubjects = 1000) # You can use an accrual time object in getSampleSizeSurvival() or # getPowerSurvival(). # For example, if the maximum number of subjects and the follow up # time needs to be calculated for a given effect size: accrualTime = getAccrualTime(accrualTime = c(0, 6, 30), accrualIntensity = c(0.1, 0.2)) getSampleSizeSurvival(accrualTime = accrualTime, pi1 = 0.4, pi2 = 0.2) # Or if the power and follow up time needs to be calculated for given # number of events and subjects: accrualTime = getAccrualTime(accrualTime = c(0, 6, 30), accrualIntensity = c(0.1, 0.2), maxNumberOfSubjects = 110) getPowerSurvival(accrualTime = accrualTime, pi1 = 0.4, pi2 = 0.2, maxNumberOfEvents = 46) # How to show accrual time details # You can use a sample size or power object as argument for the function # getAccrualTime(): sampleSize <- getSampleSizeSurvival(accrualTime = c(0, 6), accrualIntensity = c(22, 53), lambda2 = 0.05, hazardRatio = 0.8, followUpTime = 6) sampleSize accrualTime <- getAccrualTime(sampleSize) accrualTime