[Experimental] Merge two or more columns in a gtsummary table. Use show_header_names() to print underlying column names.

modify_cols_merge(x, pattern, rows = NULL)



gtsummary object


glue syntax string indicating how to merge columns in x$table_body. For example, to construct a confidence interval use "{conf.low}, {conf.high}".


predicate expression to select rows in x$table_body. Can be used to style footnote, formatting functions, missing symbols, and text formatting. Default is NULL. See details below.


gtsummary table


  1. Calling this function merely records the instructions to merge columns. The actual merging occurs when the gtsummary table is printed or converted with a function like as_gt().

  2. Because the column merging is delayed, it is recommended to perform major modifications to the table, such as those with tbl_merge() and tbl_stack(), before assigning merging instructions. Otherwise, unexpected formatting may occur in the final table.

Future Updates

There are planned updates to the implementation of this function with respect to the pattern= argument. Currently, this function replaces a numeric column with a formatted character column following pattern=. Once gt::cols_merge() gains the rows= argument the implementation will be updated to use it, which will keep numeric columns numeric. For the vast majority of users, the planned change will be go unnoticed.

Example Output

Example 1

Example 2


# Example 1 ----------------------------------
modify_cols_merge_ex1 <-
  trial %>%
  select(age, marker, trt) %>%
  tbl_summary(by = trt, missing = "no") %>%
  add_p(all_continuous() ~ "t.test",
        pvalue_fun = ~style_pvalue(., prepend_p = TRUE)) %>%
  modify_fmt_fun(statistic ~ style_sigfig) %>%
  modify_cols_merge(pattern = "t = {statistic}; {p.value}") %>%
  modify_header(statistic ~ "**t-test**")

# Example 2 ----------------------------------
modify_cols_merge_ex2 <-
  lm(marker ~ age + grade, trial) %>%
  tbl_regression() %>%
    pattern = "{estimate} ({ci})",
    rows = !is.na(estimate)