Skip to contents

Create a BLFL column

Source: R/methods.R
create_BLFL.Rd

Utilizes the BLFL method from the SDTM spec to create a baseline flag: Equal to "Y" for last record with non-missing --ORRES on or before first dose date (RFSTDTC); NA otherwise.

Usage

create_BLFL(
  tbl,
  sort_date,
  domain,
  grouping_vars = "USUBJID",
  RFSTDTC = "RFSTDTC",
  compare_date_method = "on or before"
)

Arguments

tbl

a data frame with the variables USUBJID, [domain]ORRES, RFSTDTC, and to column specified in the sort_date argument

sort_date

a string, the column name by which to sort records within each USUBJID entry before assigning the BLFL value. This is also the date compared against RFSTDTC to determine the BLFL value. This column should either already have a date class or be a character vector in the format YYYY-MM-DD

domain

a string, the SDTM domain abbreviation

grouping_vars

a character vector of columns to group by when assigning the BLFL, default is "USUBJID". The order of this vector matters.

RFSTDTC

a string, the column to use for RFSTDTC, default is "RFSTDTC"; this columns should either have a date class or a characer class in the YYYY-MM-DD format

compare_date_method

a string, one of c("on or before", "before") indicating where the baseline measurement should be evaluated on or before the study start date or just before; default is "on or before"

Value

a modified copy of tbl with the new column [domain]BLFL

See also

create_EPOCH(), calc_DY()

Examples

df <- dplyr::tibble(
  USUBJID = c(
    rep(1, 3),
    rep(2, 3)
  ),
  XXORRES = c(
    1, 2, 2,
    1, 2, NA
  ),
  XXDTC = as.Date(c(
    "2017-02-05", "2017-02-06", "2017-02-07",
    "2017-02-05", "2017-02-06", "2017-02-07"
  )),
  RFSTDTC = as.Date(c(
    rep("2017-02-05", 3),
    rep("2017-02-07", 3)
  ))
)
create_BLFL(df, sort_date = "XXDTC", domain = "XX")
#> # A tibble: 6 × 5
#>   USUBJID XXORRES XXDTC      RFSTDTC    XXBLFL
#>     <dbl>   <dbl> <date>     <date>     <chr> 
#> 1       1       1 2017-02-05 2017-02-05 Y     
#> 2       1       2 2017-02-06 2017-02-05 NA    
#> 3       1       2 2017-02-07 2017-02-05 NA    
#> 4       2       1 2017-02-05 2017-02-07 NA    
#> 5       2       2 2017-02-06 2017-02-07 Y     
#> 6       2      NA 2017-02-07 2017-02-07 NA