Add n_rate statistic to estimate_incidence_rate()

NEWS.md

@@ -5,6 +5,7 @@
 * Added the `.formats` argument to `tabulate_rsp_subgroups` and `tabulate_survival_subgroups` to allow users to specify formats.
 * Added the `riskdiff` argument to `tabulate_rsp_subgroups` and `tabulate_survival_subgroups` to allow users to add a risk difference table column, and function `control_riskdiff` to specify settings for the risk difference column.
 * Added warning to `tabulate_rsp_subgroups` when `pval` statistic is selected but `df` has not been correctly generated to add p-values to the output table.
+* Added `n_rate` statistic as a non-default option to `estimate_incidence_rate` which returns both number of events observed and estimated incidence rate.
 
 ### Bug Fixes
 * Fixed a bug in `a_surv_time` that threw an error when split only has `"is_event"`.

R/incidence_rate.R

@@ -33,6 +33,7 @@ NULL
 #'   - `n_events`: Total number of events observed.
 #'   - `rate`: Estimated incidence rate.
 #'   - `rate_ci`: Confidence interval for the incidence rate.
+#'   - `n_rate`: Total number of events observed & estimated incidence rate.
 #'
 #' @keywords internal
 s_incidence_rate <- function(df,
@@ -77,7 +78,11 @@ s_incidence_rate <- function(df,
     person_years = formatters::with_label(person_years, "Total patient-years at risk"),
     n_events = formatters::with_label(n_events, "Number of adverse events observed"),
     rate = formatters::with_label(result$rate, paste("AE rate per", num_pt_year, "patient-years")),
-    rate_ci = formatters::with_label(result$rate_ci, f_conf_level(conf_level))
+    rate_ci = formatters::with_label(result$rate_ci, f_conf_level(conf_level)),
+    n_rate = formatters::with_label(
+      c(n_events, result$rate),
+      paste("Number of adverse events observed (AE rate per", num_pt_year, "patient-years)")
+    )
   )
 }
 
@@ -94,7 +99,8 @@ a_incidence_rate <- make_afun(
     "person_years" = "xx.x",
     "n_events" = "xx",
     "rate" = "xx.xx",
-    "rate_ci" = "(xx.xx, xx.xx)"
+    "rate_ci" = "(xx.xx, xx.xx)",
+    "n_rate" = "xx (xx.x)"
   )
 )
 
@@ -142,7 +148,7 @@ estimate_incidence_rate <- function(lyt,
                                     ...,
                                     show_labels = "hidden",
                                     table_names = vars,
-                                    .stats = NULL,
+                                    .stats = c("person_years", "n_events", "rate", "rate_ci"),
                                     .formats = NULL,
                                     .labels = NULL,
                                     .indent_mods = NULL) {

R/utils_default_stats_formats_labels.R

@@ -382,7 +382,7 @@ tern_default_stats <- list(
   count_patients_with_flags = c("n", "count", "count_fraction", "count_fraction_fixed_dp", "n_blq"),
   count_values = c("n", "count", "count_fraction", "count_fraction_fixed_dp", "n_blq"),
   coxph_pairwise = c("pvalue", "hr", "hr_ci", "n_tot", "n_tot_events"),
-  estimate_incidence_rate = c("person_years", "n_events", "rate", "rate_ci"),
+  estimate_incidence_rate = c("person_years", "n_events", "rate", "rate_ci", "n_rate"),
   estimate_multinomial_response = c("n_prop", "prop_ci"),
   estimate_odds_ratio = c("or_ci", "n_tot"),
   estimate_proportion = c("n_prop", "prop_ci"),

tests/testthat/_snaps/estimate_incidence_rate.md

@@ -101,6 +101,11 @@
       attr(,"label")
       [1] "90% CI"
 
+      $n_rate
+      [1]  4.00000 44.15823
+      attr(,"label")
+      [1] "Number of adverse events observed (AE rate per 100 patient-years)"
+
 
 # estimate_incidence_rate works as expected with healthy input
 
@@ -115,3 +120,15 @@
       AE rate per 100 patient-years           26.20             57.23     
       90% CI                              (5.06, 135.73)   (22.14, 147.94)
 
+# estimate_incidence_rate `n_rate` statistic works as expected
+
+    Code
+      res
+    Output
+                                                                             A         B   
+                                                                           (N=3)     (N=3) 
+      —————————————————————————————————————————————————————————————————————————————————————
+      Number of adverse events observed                                      1         3   
+      AE rate per 100 patient-years                                        2.18      4.77  
+      Number of adverse events observed (AE rate per 100 patient-years)   1 (2.2)   3 (4.8)
+

tests/testthat/test-estimate_incidence_rate.R

@@ -109,3 +109,27 @@ testthat::test_that("estimate_incidence_rate works as expected with healthy inpu
   res <- testthat::expect_silent(result)
   testthat::expect_snapshot(res)
 })
+
+testthat::test_that("estimate_incidence_rate `n_rate` statistic works as expected", {
+  df <- data.frame(
+    USUBJID = as.character(seq(6)),
+    CNSR = c(0, 1, 1, 0, 0, 0),
+    AVAL = c(10.1, 20.4, 15.3, 20.8, 18.7, 23.4),
+    ARM = factor(c("A", "A", "A", "B", "B", "B"))
+  ) %>%
+    dplyr::mutate(is_event = CNSR == 0) %>%
+    dplyr::mutate(n_events = as.integer(is_event))
+
+  result <- basic_table() %>%
+    split_cols_by("ARM") %>%
+    add_colcounts() %>%
+    estimate_incidence_rate(
+      vars = "AVAL",
+      n_events = "n_events",
+      .stats = c("n_events", "rate", "n_rate")
+    ) %>%
+    build_table(df)
+
+  res <- testthat::expect_silent(result)
+  testthat::expect_snapshot(res)
+})