add_riskdiff: Split function to configure risk difference column

In tern: Create Common TLGs Used in Clinical Trials

Split function to configure risk difference column

Description

Wrapper function for rtables::add_combo_levels() which configures settings for the risk difference column to be added to an rtables object. To add a risk difference column to a table, this function should be used as split_fun in calls to rtables::split_cols_by(), followed by setting argument riskdiff to TRUE in all following analyze function calls.

Usage

add_riskdiff(
  arm_x,
  arm_y,
  col_label = paste0("Risk Difference (%) (95% CI)", if (length(arm_y) > 1)
    paste0("\n", arm_x, " vs. ", arm_y)),
  pct = TRUE
)

Arguments

arm_x	(string) name of reference arm to use in risk difference calculations.
arm_y	(character) names of one or more arms to compare to reference arm in risk difference calculations. A new column will be added for each value of arm_y.
col_label	(character) labels to use when rendering the risk difference column within the table. If more than one comparison arm is specified in arm_y, default labels will specify which two arms are being compared (reference arm vs. comparison arm).
pct	(flag) whether output should be returned as percentages. Defaults to TRUE.

Value

A closure suitable for use as a split function (split_fun) within rtables::split_cols_by() when creating a table layout.

See Also

stat_propdiff_ci() for details on risk difference calculation.

Examples

adae <- tern_ex_adae
adae$AESEV <- factor(adae$AESEV)

lyt <- basic_table() %>%
  split_cols_by("ARMCD", split_fun = add_riskdiff(arm_x = "ARM A", arm_y = c("ARM B", "ARM C"))) %>%
  count_occurrences_by_grade(
    var = "AESEV",
    riskdiff = TRUE
  )

tbl <- build_table(lyt, df = adae)
tbl

tern documentation built on June 20, 2025, 9:08 a.m.