Apply styling to variable group headers in gtsummary tables

Adds customizable formatting to variable group headers in gtsummary tables. Variable groups are created using gtsummary::add_variable_group_header() to organize variables into sections. This function makes group headers stand out from individual variable labels.

Usage

add_group_styling(tbl, format = c("bold", "italic"), indent_labels = 0L)

Arguments

tbl

A gtsummary table object (e.g., from tbl_summary(), tbl_regression())

format

Character vector specifying text formatting. Options include "bold", "italic", or both. Default is c("bold", "italic").

indent_labels

Integer specifying indentation level (in spaces) for variable labels under group headers. Default is 0L (left-aligned). Set to 4L to preserve gtsummary's default group indentation, or use any non-negative integer for custom spacing.

Value

A gtsummary table object with specified formatting applied to variable group headers

Details

The function targets rows where row_type == 'variable_group' and applies the specified text formatting to the label column.

By default, variable labels are left-aligned (indent_labels = 0L) to distinguish them from categorical levels and statistics. Use indent_labels = 4L to preserve the default gtsummary behavior where grouped variables are indented under their group headers.

See also

• gtsummary::modify_table_styling() for general table styling options

• gtsummary::add_variable_group_header() for creating variable group headers

Examples

# \donttest{
# Default formatting (bold and italic)
gtsummary::trial |>
  gtsummary::tbl_summary(by = trt, include = c(age, marker, grade)) |>
  gtsummary::add_variable_group_header(
    header = "Patient Characteristics",
    variables = age:grade
  ) |>
  add_group_styling()


  
Characteristic
      
Drug A

N = 981
      
Drug B

N = 1021
    
Patient Characteristics



Age
46 (37, 60)
48 (39, 56)
    Unknown
7
4
Marker Level (ng/mL)
0.84 (0.23, 1.60)
0.52 (0.18, 1.21)
    Unknown
6
4
Grade



    I
35 (36%)
33 (32%)
    II
32 (33%)
36 (35%)
    III
31 (32%)
33 (32%)
1 Median (Q1, Q3); n (%)
    

# Bold only
gtsummary::trial |>
  gtsummary::tbl_summary(by = trt, include = c(age, marker)) |>
  gtsummary::add_variable_group_header(
    header = "Demographics",
    variables = age:marker
  ) |>
  add_group_styling(format = "bold")


  
Characteristic
      
Drug A

N = 981
      
Drug B

N = 1021
    
Demographics



Age
46 (37, 60)
48 (39, 56)
    Unknown
7
4
Marker Level (ng/mL)
0.84 (0.23, 1.60)
0.52 (0.18, 1.21)
    Unknown
6
4
1 Median (Q1, Q3)
    

# Multiple group headers
gtsummary::trial |>
  gtsummary::tbl_summary(by = trt) |>
  gtsummary::add_variable_group_header(
    header = "Demographics",
    variables = age
  ) |>
  gtsummary::add_variable_group_header(
    header = "Clinical Measures",
    variables = marker:response
  ) |>
  add_group_styling()


  
Characteristic
      
Drug A

N = 981
      
Drug B

N = 1021
    
Demographics



Age
46 (37, 60)
48 (39, 56)
    Unknown
7
4
Clinical Measures



Marker Level (ng/mL)
0.84 (0.23, 1.60)
0.52 (0.18, 1.21)
    Unknown
6
4
T Stage



    T1
28 (29%)
25 (25%)
    T2
25 (26%)
29 (28%)
    T3
22 (22%)
21 (21%)
    T4
23 (23%)
27 (26%)
Grade



    I
35 (36%)
33 (32%)
    II
32 (33%)
36 (35%)
    III
31 (32%)
33 (32%)
Tumor Response
28 (29%)
33 (34%)
    Unknown
3
4
Patient Died
52 (53%)
60 (59%)
Months to Death/Censor
23.5 (17.4, 24.0)
21.2 (14.5, 24.0)
1 Median (Q1, Q3); n (%)
    

# Custom indentation for grouped variables
gtsummary::trial |>
  gtsummary::tbl_summary(by = trt, include = c(age, marker)) |>
  gtsummary::add_variable_group_header(
    header = "Patient Measures",
    variables = age:marker
  ) |>
  add_group_styling(indent_labels = 4L) # gtsummary indentation restored


  
Characteristic
      
Drug A

N = 981
      
Drug B

N = 1021
    
Patient Measures



    Age
46 (37, 60)
48 (39, 56)
    Unknown
7
4
    Marker Level (ng/mL)
0.84 (0.23, 1.60)
0.52 (0.18, 1.21)
    Unknown
6
4
1 Median (Q1, Q3)
    
# }