Adjust Hazards Underlying a Survival Curve — adjust_survival

This function compares two survival curves representing a baseline group and a treatment group, and adjusts the hazard rate for the treatment group at and beyond a specified time point to match the hazard rate for the baseline group or to follow specified adjustment mode.

Usage

adjust_survival_curve(
  baseline_survival,
  treatment_survival,
  adjustment_mode = "baseline_after_time",
  adjustment_time = 1
)

Arguments

baseline_survival

A numeric vector of survival curve for the baseline group.

treatment_survival

A numeric vector of survival curve for the treatment group. `treatment_survival` is expected to have an equal length to `baseline_survival`.

adjustment_mode

A character string specifying the adjustment mode. Options are:

`"baseline_after_time"` (default): Adjust hazard rate to match baseline at and beyond the specified time point.
`"higher_HR_after_time"`: Use the higher hazard rate between treatment and baseline after the specified time point.
`"lower_HR_after_time"`: Use the lower hazard rate between treatment and baseline after the specified time point.

adjustment_time

A numeric value representing the time point at which to start adjusting the hazard rate for the treatment group. Default is `1`. `adjustment_time` expects each element in the `baseline_survival` and `treatment_survival` survival curves (vectors) to represent the proportion of survivors at a time point. The scale or units of the values passed to the `adjustment_time` argument are implicitly equivalent to those corresponding to the survival curves.

Value

A numeric vector of adjusted hazard rates for the treatment group.

Examples

if (FALSE) { # \dontrun{
# Generate simulated survival data for a baseline and a treatment group
set.seed(123)
days_in_years <- 1:(365*3)
baseline_survival <- 1 - pweibull(q = days_in_years, shape = 1.1, scale = 650)
treatment_survival <- 1 - pweibull(q = days_in_years, shape = 4, scale = 900)

# Compare the simulated survival data
plot(
  x = days_in_years/365,
  y = baseline_survival,
  ylim = c(0, 1),
  type = "l",
  col = "red",
  xlab = "Time in years",
  ylab = "Survival"
 )
lines(x = days_in_years/365, treatment_survival, col = "blue")

# Estimate and compare the hazard rates for both groups
baseline_hazard <- convert_survival_to_hazard(baseline_survival)
treatment_hazard <- convert_survival_to_hazard(treatment_survival)

plot(
  x = days_in_years/365,
  y = baseline_hazard,
  ylim = c(min(treatment_hazard), c(max(treatment_hazard))),
  type = "l",
  col = "red",
  xlab = "Time in years",
  ylab = "Hazard rate"
 )
lines(x = days_in_years/365, treatment_hazard, col = "blue")

# Adjust the hazard rate for the treatment group to match the hazard rate for
# the baseline group at and beyond time point 365
adjusted_survival <- NeuroblastomaPSM::adjust_survival_curve(
  baseline_survival = baseline_survival,
  treatment_survival = treatment_survival,
  adjustment_time = 365
)

plot(
  x = days_in_years/365,
  y = treatment_survival,
  type = "l",
  col = "red",
  xlab = "Time",
  ylab = "Survival"
)
lines(x = days_in_years/365, y = baseline_survival, col = "blue")
lines(x = days_in_years/365, y = adjusted_survival, col = "green")

# Adjust the hazard rate for the treatment group to the higher value compared
# to the baseline group after time point 365
adjusted_survival <- NeuroblastomaPSM::adjust_survival_curve(
  baseline_survival = baseline_survival,
  treatment_survival = treatment_survival,
  adjustment_mode = "higher_HR_after_time",
  adjustment_time = 365
)

plot(
  x = days_in_years/365,
  y = treatment_survival,
  type = "l",
  col = "red",
  xlab = "Time in years",
  ylab = "Survival"
)
lines(x = days_in_years/365, y = baseline_survival, col = "blue")
lines(x = days_in_years/365, y = adjusted_survival, col = "green")

# Adjust the hazard rate for the treatment group to the lower value compared
# to the baseline group after time point 365
adjusted_survival <- NeuroblastomaPSM::adjust_survival_curve(
  baseline_survival = baseline_survival,
  treatment_survival = treatment_survival,
  adjustment_mode = "lower_HR_after_time",
  adjustment_time = 365
)

plot(
  x = days_in_years/365,
  y = treatment_survival,
  type = "l",
  col = "red",
  xlab = "Time in years",
  ylab = "Survival"
)
lines(x = days_in_years/365, y = baseline_survival, col = "blue")
lines(x = days_in_years/365, y = adjusted_survival, col = "green")
} # }