The function combines terms from a regression model, and replaces the terms
with a single row in the output table.  The p-value is calculated using
stats::anova().
combine_terms(x, formula_update, label = NULL, quiet = NULL, ...)tbl_regression object
a tbl_regression object
formula update passed to the stats::update.
This updated formula is used to construct a reduced model, and is
subsequently passed to stats::anova() to calculate the p-value for the
group of removed terms.  See the stats::update help file for proper syntax.
function's formula.= argument
Option string argument labeling the combined rows
Logical indicating whether to print messages in console. Default is
FALSE
Additional arguments passed to stats::anova
Example 1

Daniel D. Sjoberg
Review list, formula, and selector syntax used throughout gtsummary
Other tbl_regression tools: 
add_global_p(),
add_q(),
bold_italicize_labels_levels,
inline_text.tbl_regression(),
modify,
tbl_merge(),
tbl_regression(),
tbl_split(),
tbl_stack(),
tbl_strata()