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Stratified multivariable regression

Source: R/stratified_multi_reg.R
stratified_multi_reg.Rd

Fits multivariable regression models within each stratum and returns a unified wide table with one "Characteristic" column and, under bold spanners for each stratum, model N, "Adjusted <effect>", and "p-value".

Usage

stratified_multi_reg(
  data,
  outcome,
  exposures,
  stratifier,
  adjust_for = NULL,
  interaction = NULL,
  approach = "logit",
  format = c("flextable", "gt"),
  theme = c("minimal"),
  show_ref = TRUE
)

Arguments

data

A data frame containing the variables.

outcome

Character scalar; name of the outcome variable. Quoted and bare names are accepted.

exposures

Character vector of exposure variables to report. Quoted names are recommended in scripts, and bare names are also accepted.

stratifier

Character scalar; name of the stratifying variable. Quoted and bare names are accepted.

adjust_for

Optional character vector of adjustment variables. Quoted and bare names are accepted. This argument works the same way as in multi_reg().

interaction

Optional character scalar specifying one interaction term using standard formula syntax, e.g. "bmi*sex"

approach

One of "logit", "firth", "logbinomial", "poisson", "linear", "robpoisson", or "negbin"

format

One of "flextable" (default) or "gt".

theme

Preset name (e.g. "minimal", "striped", "clinical", "shaded", "jama") or primitives c("plain","zebra","lines","labels_bold","compact","header_shaded")

show_ref

Logical; if TRUE (default), display reference-category rows as "Ref.". If FALSE, hide reference rows; a message reminds users to use show_ref = TRUE when reference rows are needed.

Value

A list of class c("gtregression","stratified_multi_reg", ...) with:

table

A flextable (format = "flextable") or gt_tbl (format = "gt").

table_display

Wide data frame used to build the table.

per_stratum

Named list of per-stratum regression results.

models

Named list of fitted models by stratum.

model_summaries

Named list of model summaries by stratum.

variable_labels

Named character vector of display labels used for exposure variables.

reg_check

Named list of diagnostics by stratum.

by, levels, approach, format, source

Metadata fields.

Details

If adjust_for = NULL, all exposures are included in one multivariable model within each stratum. If adjust_for is supplied, one adjusted model is fitted per exposure within each stratum.

If exposure variables have a "label" attribute, for example from labelled::var_label(), those labels are used automatically in the displayed table. Internal matching still uses the original column names.

Examples

birthwt_data <- data_birthwt |>
  transform(
    race = factor(race, levels = c(1, 2, 3),
                  labels = c("White", "Black", "Other")),
    smoke = factor(smoke, levels = c(0, 1), labels = c("No", "Yes")),
    ht = factor(ht, levels = c(0, 1), labels = c("No", "Yes")),
    ui = factor(ui, levels = c(0, 1), labels = c("No", "Yes")),
    low = factor(low, levels = c(0, 1),
                 labels = c("Normal BW", "Low BW"))
  )

stratified_multi <- stratified_multi_reg(
  data = birthwt_data,
  outcome = "low",
  exposures = c("age", "lwt", "smoke", "ht"),
  stratifier = "race",
  approach = "logit",
  format = "gt"
)
#> Running stratified multivariable regression by: race
#>   > Stratum: race = White
#>   > Stratum: race = Black
#>   > Stratum: race = Other

stratified_adjusted <- stratified_multi_reg(
  data = birthwt_data,
  outcome = "low",
  exposures = c("smoke", "ht", "ui"),
  stratifier = "race",
  adjust_for = c("age", "lwt"),
  approach = "logit",
  format = "gt"
)
#> Running stratified multivariable regression by: race
#>   > Stratum: race = White
#>   > Stratum: race = Black
#>   > Stratum: race = Other