Exclusion Flowchart Using DiagrammeR

Source: R/flowex.R

This function plots a flow chart using grViz. It is restricted to the simple case of sequential exclusions from a single study population and not suited for CONSORT flowcharts for a parallel-group study (i.e., a randomized-controlled trial). The left column describes the flow of the group that ends up being included. The right column describes exclusions for various reasons.

Generate the design using make_exclusions.

exclusion_flowchart(design, width = 3)

Arguments

design

Tibble with the following columns:

  • left Text for the left box of each row.

  • n_left Count to be shown as 'n =' in the bottom of the left box. To skip, use NA_integer_.

  • right Text for the right box of each row.

  • n_right Count to be shown as 'n =' in the bottom of the right box. To skip, use NA_integer_.

width

Minimum width for all boxes. Defaults to 3 (inches).

Value

Plot rendered using grViz. For a design with three rows, the following pseudo-code would be generated:


  grViz(paste0("digraph flowchart {
    node [fontname = Helvetica, shape = rectangle, width = 4]
    tab1a [label = 'left[1] \nn = ", n_left[1],  "']
    tab1b [label = 'right[1]\nn = ", n_right[1], "']
    tab2a [label = 'left[2] \nn = ", n_left[2],  "']
    tab2b [label = 'right[2]\nn = ", n_right[2], "']
    tab3a [label = 'left[3] \nn = ", n_left[3],  "']

    { rank = same; tab1a; tab1b; }
    { rank = same; tab2a; tab2b; }

    tab1a -> tab2a -> tab3a;
    tab1a -> tab1b;
    tab2a -> tab2b;
    }"))

Details

Note grViz does not automatically generate line breaks. To avoid extra-wide boxes, manually supply line breaks using \n. See example.

Example Output

Examples

# Generate a flow chart for two steps of exclusions:
design <- tibble::tribble(
  ~left,               ~n_left, ~right,              ~n_right,
  "Study base",        1000,    "Not sampled",       250,
  "Study population",  750,     "Participants with\nmissing exposure data", 100,
  "Complete-case set", 650,     "",                  NA_integer_)

# Plot
exclusion_flowchart(design, width = 2)