Readmission Risk Pool (RRP) estimates the probability of a
first readmission strictly after an assessment time through 30
elapsed days after discharge. The endpoint stays anchored to
the original discharge. readmit supplies the project,
eligibility, history, and product operations; the project owner supplies
the source mapping and risk provider.
This small example uses one fixed analytical time and an illustrative formula. It does not provide a clinically validated model. For source mapping, a trained assessment-time model, repeated assessments, and application customization, see Implementing RRP: A Simulated Hospital Walkthrough.
Create a project and supply canonical facts
Initialization creates an ordinary project directory. Its
R/produce-canonical.R and R/calculate-risk.R
scripts are the owner’s two analytical implementation points. We replace
their initial stubs below.
project <- rrp_project_init(tempfile("rrp-getting-started-"), "example-rrp")
as_of_time <- as.POSIXct("2026-01-10 12:00:00", tz = "UTC")
discharge_time <- as.POSIXct(c(
"2026-01-08 12:00:00", "2026-01-01 12:00:00",
"2025-12-01 12:00:00", "2026-01-04 12:00:00"
), tz = "UTC")
episodes <- data.frame(
episode_id = paste0("episode-", 1:4),
patient_id = paste0("patient-", 1:4),
index_encounter_id = paste0("encounter-", 1:4),
admission_time = discharge_time - 2 * 86400,
discharge_time = discharge_time
)
events <- data.frame(
terminal_event_id = c("event-2", "event-4"),
episode_id = c("episode-2", "episode-4"),
event_type = c("readmission", "death"),
occurred_at = as.POSIXct(c(
"2026-01-06 12:00:00", "2026-01-07 12:00:00"
), tz = "UTC"),
available_at = as.POSIXct(c(
"2026-01-07 12:00:00", "2026-01-08 12:00:00"
), tz = "UTC")
)
saveRDS(list(discharge_episode = episodes, terminal_event = events),
file.path(project, "canonical.rds"))All four episodes were discharged by this assessment time. Episode 1 is still eligible, episode 2 has a known readmission, episode 3 has passed its original 30-day endpoint, and episode 4 has a known death. The event occurrence and availability times are separate UTC facts. An operational source mapper should select the complete relevant discharge population for each assessment time; this saved list is only a one-snapshot example.
The project-authored mapper reads those typed facts. The provider’s
illustrative probability is 0.30 scaled by the share of the original
30-day interval still remaining. It uses the package’s
remaining_seconds request field, so it does not restart the
follow-up window. This formula has no clinical meaning.
writeLines(c(
"rrp_produce_canonical <- function(project_root, as_of_time) {",
" readRDS(file.path(project_root, 'canonical.rds'))",
"}"
), file.path(project, "R", "produce-canonical.R"))
writeLines(c(
"rrp_calculate_risk <- function(project_root, request) {",
" list(probability = 0.30 * request$remaining_seconds / (30 * 86400))",
"}"
), file.path(project, "R", "calculate-risk.R"))
rrp_project_validate(project)
rrp_state_init(project)
#> duckdb keeps downloaded extensions and secrets in a temporary directory:
#> ℹ /tmp/Rtmp69sCom/duckdb
#> This is removed when the R session ends.
#> • Extensions are re-downloaded each session.
#> • Secrets are lost.
#> ℹ Run duckdb(shared_home = TRUE) (or create ~/.duckdb) to keep them (suitable for most users).
#> ℹ Run duckdb(shared_home = FALSE) to accept the temporary directory (and silence this message).
#> ℹ See ?duckdb_storage for details and alternatives.rrp_project_validate() checks that required project
resources and functions load. It does not test the supplied data,
formula, or clinical suitability.
Run and inspect an assessment
assessment <- rrp_run(project, as_of_time)
#> duckdb keeps downloaded extensions and secrets in a temporary directory:
#> ℹ /tmp/Rtmp69sCom/duckdb
#> This is removed when the R session ends.
#> • Extensions are re-downloaded each session.
#> • Secrets are lost.
#> ℹ Run duckdb(shared_home = TRUE) (or create ~/.duckdb) to keep them (suitable for most users).
#> ℹ Run duckdb(shared_home = FALSE) to accept the temporary directory (and silence this message).
#> ℹ See ?duckdb_storage for details and alternatives.
#> duckdb keeps downloaded extensions and secrets in a temporary directory:
#> ℹ /tmp/Rtmp69sCom/duckdb
#> This is removed when the R session ends.
#> • Extensions are re-downloaded each session.
#> • Secrets are lost.
#> ℹ Run duckdb(shared_home = TRUE) (or create ~/.duckdb) to keep them (suitable for most users).
#> ℹ Run duckdb(shared_home = FALSE) to accept the temporary directory (and silence this message).
#> ℹ See ?duckdb_storage for details and alternatives.
assessment[c("episodes_processed", "accepted", "provider_failures", "ineligible")]
#> $episodes_processed
#> [1] 4
#>
#> $accepted
#> [1] 1
#>
#> $provider_failures
#> [1] 0
#>
#> $ineligible
#> [1] 3
status <- rrp_project_status(project)
#> duckdb keeps downloaded extensions and secrets in a temporary directory:
#> ℹ /tmp/Rtmp69sCom/duckdb
#> This is removed when the R session ends.
#> • Extensions are re-downloaded each session.
#> • Secrets are lost.
#> ℹ Run duckdb(shared_home = TRUE) (or create ~/.duckdb) to keep them (suitable for most users).
#> ℹ Run duckdb(shared_home = FALSE) to accept the temporary directory (and silence this message).
#> ℹ See ?duckdb_storage for details and alternatives.
status[c("state_initialized", "run_count")]
#> $state_initialized
#> [1] TRUE
#>
#> $run_count
#> [1] 1
history <- rrp_inspect_history(project)
#> duckdb keeps downloaded extensions and secrets in a temporary directory:
#> ℹ /tmp/Rtmp69sCom/duckdb
#> This is removed when the R session ends.
#> • Extensions are re-downloaded each session.
#> • Secrets are lost.
#> ℹ Run duckdb(shared_home = TRUE) (or create ~/.duckdb) to keep them (suitable for most users).
#> ℹ Run duckdb(shared_home = FALSE) to accept the temporary directory (and silence this message).
#> ℹ See ?duckdb_storage for details and alternatives.
history[c("episode_id", "disposition", "probability")]
#> episode_id disposition probability
#> 1 episode-1 accepted 0.28
#> 2 episode-2 known_readmission NA
#> 3 episode-3 window_closed NA
#> 4 episode-4 known_death NA
stopifnot(assessment$accepted == 1L, assessment$ineligible == 3L,
isTRUE(all.equal(history$probability[history$disposition == "accepted"],
0.28)))The package called the provider only for eligible episode 1 and retained its 0.28 illustrative estimate. The other three rows explain why those episodes were ineligible. History remains available for later inspection.
Refresh the three products
Products are derived from retained history; refreshing them does not repeat the assessment or edit the project-owned application.
products <- rrp_refresh_products(project)
#> duckdb keeps downloaded extensions and secrets in a temporary directory:
#> ℹ /tmp/Rtmp69sCom/duckdb
#> This is removed when the R session ends.
#> • Extensions are re-downloaded each session.
#> • Secrets are lost.
#> ℹ Run duckdb(shared_home = TRUE) (or create ~/.duckdb) to keep them (suitable for most users).
#> ℹ Run duckdb(shared_home = FALSE) to accept the temporary directory (and silence this message).
#> ℹ See ?duckdb_storage for details and alternatives.
current_risk <- read.csv(products$files[["current_risk"]])
trajectory <- read.csv(products$files[["trajectory"]])
scope <- read.csv(products$files[["scope"]])
current_risk[c("episode_id", "disposition", "probability")]
#> episode_id disposition probability
#> 1 episode-1 accepted 0.28
trajectory[c("episode_id", "probability")]
#> episode_id probability
#> 1 episode-1 0.28
scope[c("episodes_assessed", "eligible_count", "accepted_count",
"known_readmission_count", "known_death_count", "window_closed_count")]
#> episodes_assessed eligible_count accepted_count known_readmission_count
#> 1 4 1 1 1
#> known_death_count window_closed_count
#> 1 1 1
stopifnot(nrow(current_risk) == 1L, nrow(trajectory) == 1L,
scope$episodes_assessed == 4L)The current-risk CSV contains eligible episode 1; the trajectory CSV
contains its recorded accepted estimate; and the scope CSV counts all
four outcomes. The project-contained Shiny app reads these products.
After installing its runtime packages as listed in the project’s
README.md, launch it manually: