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Number Needed to Treat (NNT) Plot

Source: R/hazard-plot.R
nnt_plot.Rd

Superseded.

nnt_plot() has been superseded by the S3 constructor hv_nnt() plus plot.hv_nnt().

Plots the number needed to treat (NNT) and/or absolute risk reduction (ARR) over time, with optional confidence bands. Covers the NNT component of tp.hp.numtreat.survdiff.matched.sas.

SAS context: The SAS template computes NNT at discrete time points (1, 5, 10, 15, 20 years) from the HAZDIFL macro output, then connects them as a curve. Export the NNT dataset and pass it directly, or use sample_nnt_data() for examples.

Usage

nnt_plot(
  nnt_data,
  x_col = "time",
  estimate_col = "nnt",
  lower_col = NULL,
  upper_col = NULL,
  na_rm = TRUE,
  ci_alpha = 0.2,
  line_width = 1
)

Arguments

nnt_data

Data frame of pre-computed NNT estimates. See sample_nnt_data().

x_col

Name of the time column. Default "time".

estimate_col

Name of the NNT column. Default "nnt".

lower_col

Name of the lower CI column, or NULL. Default NULL.

upper_col

Name of the upper CI column, or NULL. Default NULL.

na_rm

Remove NA NNT values (undefined when ARR ≈ 0) before plotting. Default TRUE.

ci_alpha

Transparency of the CI ribbon. Default 0.20.

line_width

Line width. Default 1.0.

Value

A ggplot2::ggplot() object.

References

SAS template: tp.hp.numtreat.survdiff.matched.sas.

See also

sample_nnt_data(), survival_difference_plot(), hazard_plot()

Examples

library(ggplot2)

nnt_dat <- sample_nnt_data(
  n = 500, time_max = 20,
  groups = c("SVG" = 1.0, "ITA" = 0.75)
)

# --- (1) NNT curve over time --------------------------------------------
# Matches tp.hp.numtreat.survdiff.matched.sas (NNT panel).
# NNT decreases as the treatment benefit accumulates over time.
nnt_plot(
  nnt_dat,
  lower_col = "nnt_lower",
  upper_col = "nnt_upper"
) +
  scale_colour_manual(values = c("steelblue"), guide = "none") +
  scale_fill_manual(values = c("steelblue"), guide = "none") +
  scale_x_continuous(limits = c(0, 20), breaks = seq(0, 20, 5)) +
  scale_y_continuous(limits = c(0, 50), breaks = seq(0, 50, 10)) +
  labs(x = "Years", y = "Number Needed to Treat (NNT)") +
  hv_theme("poster")
#> Warning: Removed 248 rows containing missing values or values outside the scale range
#> (`geom_ribbon()`).
#> Warning: Removed 27 rows containing missing values or values outside the scale range
#> (`geom_line()`).


# --- (2) ARR curve over time (same data, different column) ---------------
# Absolute risk reduction (%) increases over time as survival curves diverge.
nnt_plot(
  nnt_dat,
  estimate_col = "arr",
  lower_col    = "arr_lower",
  upper_col    = "arr_upper"
) +
  scale_colour_manual(values = c("firebrick"), guide = "none") +
  scale_fill_manual(values = c("firebrick"), guide = "none") +
  scale_x_continuous(limits = c(0, 20), breaks = seq(0, 20, 5)) +
  scale_y_continuous(limits = c(0, 50),
                     labels = function(x) paste0(x, "%")) +
  labs(x = "Years", y = "Absolute Risk Reduction (%)") +
  hv_theme("poster")
#> Warning: Removed 178 rows containing missing values or values outside the scale range
#> (`geom_ribbon()`).