kmdiff: Estimate of Milestone Survival Difference

In trtswitch: Treatment Switching

Estimate of Milestone Survival Difference

Description

Obtains the estimate of milestone survival difference between two treatment groups.

Usage

kmdiff(
  data,
  stratum = "",
  treat = "treat",
  time = "time",
  time2 = "",
  event = "event",
  weight = "",
  milestone = 0,
  survDiffH0 = 0,
  conflev = 0.95
)

Arguments

data	The input data frame that contains the following variables: stratum: The stratum. treat: The treatment. time: The follow-up time for right censored data, or the left end of each interval for counting process data. time2: The right end of each interval for counting process data. Intervals are assumed to be open on the left and closed on the right, and event indicates whether an event occurred at the right end of each interval. event: The event indicator, 1=event, 0=no event. weight: The weight for each observation.
stratum	The name of the stratum variable in the input data.
treat	The name of the treatment variable in the input data.
time	The name of the time variable or the left end of each interval for counting process data in the input data.
time2	The name of the right end of each interval for counting process data in the input data.
event	The name of the event variable in the input data.
weight	The name of the weight variable in the input data.
milestone	The milestone time at which to calculate the survival probability.
survDiffH0	The difference in milestone survival probabilities under the null hypothesis. Defaults to 0 for superiority test.
conflev	The level of the two-sided confidence interval for the difference in milestone survival probabilities. Defaults to 0.95.

Value

A data frame with the following variables:

• milestone: The milestone time relative to randomization.

• survDiffH0: The difference in milestone survival probabilities under the null hypothesis.

• surv1: The estimated milestone survival probability for the treatment group.

• surv2: The estimated milestone survival probability for the control group.

• survDiff: The estimated difference in milestone survival probabilities.

• vsurv1: The variance for surv1.

• vsurv2: The variance for surv2.

• sesurvDiff: The standard error for survDiff.

• survDiffZ: The Z-statistic value.

• survDiffPValue: The two-sided p-value.

• lower: The lower bound of confidence interval.

• upper: The upper bound of confidence interval.

• conflev: The level of confidence interval.

Author(s)

Kaifeng Lu, [e-mail]

Examples

kmdiff(data = rawdata[rawdata$iterationNumber == 1, ],
       stratum = "stratum", treat = "treatmentGroup",
       time = "timeUnderObservation", event = "event",
       milestone = 12)
             

trtswitch documentation built on Jan. 10, 2026, 5:08 p.m.