Create Time-to-Deterioration Analysis — create_ttd

Performs time-to-deterioration (TTD) analysis for PRO endpoints. Deterioration is defined as a decrease from baseline exceeding the MCID.

Usage

create_ttd_analysis(
  data,
  subject_var = "USUBJID",
  trt_var = "TRT01P",
  param_var = "PARAMCD",
  paramcd = NULL,
  value_var = "AVAL",
  base_var = "BASE",
  chg_var = "CHG",
  time_var = "ADY",
  visit_var = "AVISITN",
  threshold,
  direction = c("decrease", "increase"),
  definition = c("first", "confirmed"),
  confirmation_visits = 1,
  censor_at = NULL
)

Arguments

data: Data frame with longitudinal PRO data
subject_var: Character. Subject ID variable. Default: "USUBJID"
trt_var: Character. Treatment variable. Default: "TRT01P"
param_var: Character. Parameter variable. Default: "PARAMCD"
paramcd: Character. Parameter code to analyze. Default: NULL (uses first)
value_var: Character. Value variable. Default: "AVAL"
base_var: Character. Baseline value variable. Default: "BASE"
chg_var: Character. Change from baseline variable. Default: "CHG"
time_var: Character. Time/day variable. Default: "ADY"
visit_var: Character. Visit number variable. Default: "AVISITN"
threshold: Numeric. MCID threshold for deterioration (positive = improvement)
direction: Character. "decrease" if lower is worse, "increase" if higher is worse
definition: Character. "first" or "confirmed" deterioration. Default: "first"
confirmation_visits: Integer. Visits to confirm (for definition="confirmed")
censor_at: Numeric. Time to censor if no event. Default: max time in data

Value

A list with components:

ttd_data: Prepared time-to-deterioration data frame
km_fit: Kaplan-Meier fit object from survfit
summary_table: Summary statistics by treatment group
threshold: MCID threshold used
direction: Direction of deterioration
definition: Deterioration definition used
n_subjects: Total number of subjects
n_events: Total number of deterioration events

Examples

if (FALSE) { # \dontrun{
# Create time-to-deterioration analysis
ttd <- create_ttd_analysis(
  data = pro_data,
  threshold = 5,
  direction = "decrease"
)

# Access summary table
ttd$summary_table
} # }