filter_ard_hierarchical: Filter Stacked Hierarchical ARDs

In cards: Analysis Results Data

Filter Stacked Hierarchical ARDs

Description

This function is used to filter stacked hierarchical ARDs.

For the purposes of this function, we define a "variable group" as a combination of ARD rows grouped by the combination of all their variable levels, but excluding any by variables.

Usage

filter_ard_hierarchical(
  x,
  filter,
  var = NULL,
  keep_empty = FALSE,
  quiet = FALSE
)

Arguments

x	(card) a stacked hierarchical ARD of class 'card' created using ard_stack_hierarchical() or ard_stack_hierarchical_count().
filter	(expression) an expression that is used to filter variable groups of the hierarchical ARD. See the Details section below.
var	(tidy-select) hierarchy variable from x to perform filtering on. If NULL, the last hierarchy variable from x (dplyr::last(attributes(x)$args$variables)) will be used.
keep_empty	(scalar logical) Logical argument indicating whether to retain summary rows corresponding to hierarchy sections that have had all rows filtered out. Default is FALSE.
quiet	(logical) logical indicating whether to suppress any messaging. Default is FALSE.

Details

The filter argument can be used to filter out variable groups of a hierarchical ARD which do not meet the requirements provided as an expression. Variable groups can be filtered on the values of any of the possible statistics (n, p, and N) provided they are included at least once in the ARD, as well as the values of any by variables.

Additionally, filters can be applied on individual levels of the by variable via the n_XX, N_XX, and p_XX statistics, where each XX represents the index of the by variable level to select the statistic from. For example, filter = n_1 > 5 will check whether n values for the first level of by are greater than 5 in each row group.

Overall statistics for each row group can be used in filters via the n_overall, N_overall, and p_overall statistics. If the ARD is created with parameter overall=TRUE, then these overall statistics will be extracted directly from the ARD, otherwise the statistics will be derived where possible. If overall=FALSE, then n_overall can only be derived if the n statistic is present in the ARD for the filter variable, N_overall if the N statistic is present for the filter variable, and p_overall if both the n and N statistics are present for the filter variable.

By default, filters will be applied at the level of the innermost hierarchy variable, i.e. the last variable supplied to variables. If filters should instead be applied at the level of one of the outer hierarchy variables, the var parameter can be used to select a different variable to filter on. When var is set to a different (outer) variable and a level of the variable does not meet the filtering criteria then the section corresponding to that variable level and all sub-sections within that section will be removed.

To illustrate how the function works, consider the typical example below where the AE summaries are provided by treatment group.

ADAE |>
  dplyr::filter(AESOC == "GASTROINTESTINAL DISORDERS",
                AEDECOD %in% c("VOMITING", "DIARRHOEA")) |>
  ard_stack_hierarchical(
    variables = c(AESOC, AEDECOD),
    by = TRTA,
    denominator = ADSL,
    id = USUBJID
  )

SOC / AE	Placebo	Xanomeline High Dose	Xanomeline Low Dose
GASTROINTESTINAL DISORDERS	11 (13%)	10 (12%)	8 (9.5%)
DIARRHOEA	9 (10%)	4 (4.8%)	5 (6.0%)
VOMITING	3 (3.5%)	7 (8.3%)	3 (3.6%)

Filters are applied to the summary statistics of the innermost variable in the hierarchy by default—AEDECOD in this case. If we wanted to filter based on SOC rates instead of AE rates we could specify var = AESOC instead. If any of the summary statistics meet the filter requirement for any of the treatment groups, the entire row is retained. For example, if filter = n >= 9 were passed, the criteria would be met for DIARRHOEA as the Placebo group observed 9 AEs and as a result the summary statistics for the other treatment groups would be retained as well. Conversely, no treatment groups' summary statistics satisfy the filter requirement for VOMITING so all rows associated with this AE would be removed.

In addition to filtering on individual statistic values, filters can be applied across the treatment groups (i.e. across all by variable values) by using aggregate functions such as sum() and mean(). For simplicity, it is suggested to use the XX_overall statistics in place of sum(XX) in equivalent scenarios. For example, n_overall is equivalent to sum(n). A value of filter = sum(n) >= 18 (or filter = n_overall >= 18) retains AEs where the sum of the number of AEs across the treatment groups is greater than or equal to 18.

If filter = n_overall >= 18 and var = AESOC then all rows corresponding to an SOC with an overall rate less than 18 - including all AEs within that SOC - will be removed.

If ard_stack_hierarchical(overall=TRUE) was run, the overall column is not considered in any filtering except for XX_overall statistics, if specified.

If ard_stack_hierarchical(over_variables=TRUE) was run, any overall statistics are kept regardless of filtering.

Some examples of possible filters:

• filter = n > 5: keep AEs where one of the treatment groups observed more than 5 AEs

• filter = n == 2 & p < 0.05: keep AEs where one of the treatment groups observed exactly 2 AEs and one of the treatment groups observed a proportion less than 5%

• filter = n_overall >= 4: keep AEs where there were 4 or more AEs observed across the treatment groups

• filter = mean(n) > 4 | n > 3: keep AEs where the mean number of AEs is 4 or more across the treatment groups or one of the treatment groups observed more than 3 AEs

• filter = n_2 > 2: keep AEs where the "Xanomeline High Dose" treatment group (second by variable level) observed more than 2 AEs

Value

an ARD data frame of class 'card'

See Also

sort_ard_hierarchical()

Examples

# create a base AE ARD
ard <- ard_stack_hierarchical(
  ADAE,
  variables = c(AESOC, AEDECOD),
  by = TRTA,
  denominator = ADSL,
  id = USUBJID,
  overall = TRUE
)

# Example 1 ----------------------------------
# Keep AEs from TRTA groups where more than 3 AEs are observed across the group
filter_ard_hierarchical(ard, sum(n) > 3)

# Example 2 ----------------------------------
# Keep AEs where at least one level in the TRTA group has more than 3 AEs observed
filter_ard_hierarchical(ard, n > 3)

# Example 3 ----------------------------------
# Keep AEs that have an overall prevalence of greater than 5%
filter_ard_hierarchical(ard, sum(n) / sum(N) > 0.05)

# Example 4 ----------------------------------
# Keep AEs that have a difference in prevalence of greater than 3% between reference group with
# `TRTA = "Xanomeline High Dose"` and comparison group with `TRTA = "Xanomeline Low Dose"`
filter_ard_hierarchical(ard, abs(p_2 - p_3) > 0.03)

# Example 5 ----------------------------------
# Keep AEs from SOCs that have an overall prevalence of greater than 20%
filter_ard_hierarchical(ard, p_overall > 0.20, var = AESOC)

cards documentation built on Dec. 2, 2025, 9:07 a.m.