derive_var_extreme_flag: Add a Variable Flagging the First or Last Observation Within Each By Group

Description

Add a variable flagging the first or last observation within each by group

Usage

derive_var_extreme_flag(
  dataset,
  by_vars,
  order,
  new_var,
  mode,
  true_value = "Y",
  false_value = NA_character_,
  flag_all = FALSE,
  check_type = "warning"
)

Value

The input dataset with the new flag variable added

Arguments

dataset

Input dataset

The variables specified by the by_vars argument are expected to be in the dataset.

by_vars

Grouping variables

Permitted Values: list of variables created by exprs() e.g. exprs(USUBJID, VISIT)

order

Sort order

The first or last observation is determined with respect to the specified order.

For handling of NAs in sorting variables see Sort Order.

Permitted Values: list of variables or functions of variables

new_var

Variable to add

The specified variable is added to the output dataset. It is set to the value set in true_value for the first or last observation (depending on the mode) of each by group.

Permitted Values: list of name-value pairs

mode

Flag mode

Determines of the first or last observation is flagged.

Permitted Values: "first", "last"

true_value

True value

The value for the specified variable new_var, applicable to the first or last observation (depending on the mode) of each by group.

Permitted Values: An atomic scalar

false_value

False value

The value for the specified variable new_var, NOT applicable to the first or last observation (depending on the mode) of each by group.

Permitted Values: An atomic scalar

flag_all

Flag setting

A logical value where if set to TRUE, all records are flagged and no error or warning is issued if the first or last record is not unique.

check_type

Check uniqueness?

If "warning" or "error" is specified, the specified message is issued if the observations of the input dataset are not unique with respect to the by variables and the order.

Default: "warning"

Permitted Values: "none", "warning", "error"

Details

For each group (with respect to the variables specified for the by_vars parameter), new_var is set to "Y" for the first or last observation (with respect to the order specified for the order parameter and the flag mode specified for the mode parameter). In the case where the user wants to flag multiple records of a grouping, for example records that all happen on the same visit and time, the argument flag_all can be set to TRUE. Otherwise, new_var is set to NA. Thus, the direction of "worst" is considered fixed for all parameters in the dataset depending on the order and the mode, i.e. for every parameter the first or last record will be flagged across the whole dataset.

Examples

Run this code

library(tibble)
library(dplyr, warn.conflicts = FALSE)
example_vs <- tribble(
  ~USUBJID, ~VSTESTCD,      ~VISIT, ~VISITNUM, ~VSTPTNUM, ~VSSTRESN,
  "1001",     "DIABP", "SCREENING",         1,        10,        64,
  "1001",     "DIABP", "SCREENING",         1,        11,        66,
  "1001",     "DIABP",  "BASELINE",         2,       100,        68,
  "1001",     "DIABP",  "BASELINE",         2,       101,        68,
  "1001",     "DIABP",    "WEEK 2",         3,       200,        72,
  "1001",     "DIABP",    "WEEK 2",         3,       201,        71,
  "1001",     "DIABP",    "WEEK 4",         4,       300,        70,
  "1001",     "DIABP",    "WEEK 4",         4,       301,        70
)

# Flag last value for each patient, test, and visit, baseline observations are ignored
example_vs %>%
  restrict_derivation(
    derivation = derive_var_extreme_flag,
    args = params(
      by_vars = exprs(USUBJID, VSTESTCD, VISIT),
      order = exprs(VSTPTNUM),
      new_var = LASTFL,
      mode = "last"
    ),
    filter = VISIT != "BASELINE"
  ) %>%
  arrange(USUBJID, VSTESTCD, VISITNUM, VSTPTNUM) %>%
  select(USUBJID, VSTESTCD, VISIT, VSTPTNUM, VSSTRESN, LASTFL)

# Baseline (ABLFL) examples:

input <- tribble(
  ~STUDYID, ~USUBJID,  ~PARAMCD,     ~AVISIT,                  ~ADT, ~AVAL,    ~DTYPE,
  "TEST01",  "PAT01", "PARAM01",  "BASELINE", as.Date("2021-04-27"),  15.0,        NA,
  "TEST01",  "PAT01", "PARAM01",  "BASELINE", as.Date("2021-04-25"),  14.0,        NA,
  "TEST01",  "PAT01", "PARAM01",  "BASELINE", as.Date("2021-04-23"),  15.0, "AVERAGE",
  "TEST01",  "PAT01", "PARAM01",    "WEEK 1", as.Date("2021-04-27"),  10.0, "AVERAGE",
  "TEST01",  "PAT01", "PARAM01",    "WEEK 2", as.Date("2021-04-30"),  12.0,        NA,
  "TEST01",  "PAT02", "PARAM01", "SCREENING", as.Date("2021-04-27"),  15.0, "AVERAGE",
  "TEST01",  "PAT02", "PARAM01",  "BASELINE", as.Date("2021-04-25"),  14.0, "AVERAGE",
  "TEST01",  "PAT02", "PARAM01",  "BASELINE", as.Date("2021-04-23"),  15.0, "AVERAGE",
  "TEST01",  "PAT02", "PARAM01",    "WEEK 1", as.Date("2021-04-27"),  10.0, "AVERAGE",
  "TEST01",  "PAT02", "PARAM01",    "WEEK 2", as.Date("2021-04-30"),  12.0, "AVERAGE",
  "TEST01",  "PAT01", "PARAM02", "SCREENING", as.Date("2021-04-27"),  15.0, "AVERAGE",
  "TEST01",  "PAT01", "PARAM02", "SCREENING", as.Date("2021-04-25"),  14.0, "AVERAGE",
  "TEST01",  "PAT01", "PARAM02", "SCREENING", as.Date("2021-04-23"),  15.0,        NA,
  "TEST01",  "PAT01", "PARAM02",  "BASELINE", as.Date("2021-04-27"),  10.0, "AVERAGE",
  "TEST01",  "PAT01", "PARAM02",    "WEEK 2", as.Date("2021-04-30"),  12.0,        NA,
  "TEST01",  "PAT02", "PARAM02", "SCREENING", as.Date("2021-04-27"),  15.0,        NA,
  "TEST01",  "PAT02", "PARAM02",  "BASELINE", as.Date("2021-04-25"),  14.0,        NA,
  "TEST01",  "PAT02", "PARAM02",    "WEEK 1", as.Date("2021-04-23"),  15.0,        NA,
  "TEST01",  "PAT02", "PARAM02",    "WEEK 1", as.Date("2021-04-27"),  10.0,        NA,
  "TEST01",  "PAT02", "PARAM02",  "BASELINE", as.Date("2021-04-30"),  12.0,        NA
)

# Last observation
restrict_derivation(
  input,
  derivation = derive_var_extreme_flag,
  args = params(
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(ADT),
    new_var = ABLFL,
    mode = "last"
  ),
  filter = AVISIT == "BASELINE"
)

# Worst observation - Direction = High
restrict_derivation(
  input,
  derivation = derive_var_extreme_flag,
  args = params(
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(AVAL, ADT),
    new_var = ABLFL,
    mode = "last"
  ),
  filter = AVISIT == "BASELINE"
)

# Worst observation - Direction = Lo
restrict_derivation(
  input,
  derivation = derive_var_extreme_flag,
  args = params(
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(desc(AVAL), ADT),
    new_var = ABLFL,
    mode = "last"
  ),
  filter = AVISIT == "BASELINE"
)

# Average observation
restrict_derivation(
  input,
  derivation = derive_var_extreme_flag,
  args = params(
    by_vars = exprs(USUBJID, PARAMCD),
    order = exprs(ADT, desc(AVAL)),
    new_var = ABLFL,
    mode = "last"
  ),
  filter = AVISIT == "BASELINE" & DTYPE == "AVERAGE"
)

# OCCURDS Examples
example_ae <- tribble(
  ~USUBJID,         ~AEBODSYS,    ~AEDECOD,   ~AESEV, ~AESTDY, ~AESEQ,
  "1015", "GENERAL DISORDERS",  "ERYTHEMA",   "MILD",       2,      1,
  "1015", "GENERAL DISORDERS",  "PRURITUS",   "MILD",       2,      2,
  "1015",      "GI DISORDERS", "DIARRHOEA",   "MILD",       8,      3,
  "1023", "CARDIAC DISORDERS",  "AV BLOCK",   "MILD",      22,      4,
  "1023",    "SKIN DISORDERS",  "ERYTHEMA",   "MILD",       3,      1,
  "1023",    "SKIN DISORDERS",  "ERYTHEMA", "SEVERE",       5,      2,
  "1023",    "SKIN DISORDERS",  "ERYTHEMA",   "MILD",       8,      3
)

# Most severe AE first occurrence per patient
example_ae %>%
  mutate(
    TEMP_AESEVN =
      as.integer(factor(AESEV, levels = c("SEVERE", "MODERATE", "MILD")))
  ) %>%
  derive_var_extreme_flag(
    new_var = AOCCIFL,
    by_vars = exprs(USUBJID),
    order = exprs(TEMP_AESEVN, AESTDY, AESEQ),
    mode = "first"
  ) %>%
  arrange(USUBJID, AESTDY, AESEQ) %>%
  select(USUBJID, AEDECOD, AESEV, AESTDY, AESEQ, AOCCIFL)

# Most severe AE first occurrence per patient (flag all cases)
example_ae %>%
  mutate(
    TEMP_AESEVN =
      as.integer(factor(AESEV, levels = c("SEVERE", "MODERATE", "MILD")))
  ) %>%
  derive_var_extreme_flag(
    new_var = AOCCIFL,
    by_vars = exprs(USUBJID),
    order = exprs(TEMP_AESEVN, AESTDY),
    mode = "first",
    flag_all = TRUE
  ) %>%
  arrange(USUBJID, AESTDY) %>%
  select(USUBJID, AEDECOD, AESEV, AESTDY, AOCCIFL)

# Most severe AE first occurrence per patient per body system
example_ae %>%
  mutate(
    TEMP_AESEVN =
      as.integer(factor(AESEV, levels = c("SEVERE", "MODERATE", "MILD")))
  ) %>%
  derive_var_extreme_flag(
    new_var = AOCCSIFL,
    by_vars = exprs(USUBJID, AEBODSYS),
    order = exprs(TEMP_AESEVN, AESTDY, AESEQ),
    mode = "first"
  ) %>%
  arrange(USUBJID, AESTDY, AESEQ) %>%
  select(USUBJID, AEBODSYS, AESEV, AESTDY, AOCCSIFL)