derive_locf_records: Derive LOCF (Last Observation Carried Forward) Records

In admiral: ADaM in R Asset Library

Derive LOCF (Last Observation Carried Forward) Records

Description

Adds LOCF records as new observations for each 'by group' when the dataset does not contain observations for missed visits/time points.

Usage

derive_locf_records(
  dataset,
  dataset_ref,
  by_vars,
  analysis_var = AVAL,
  order,
  keep_vars = NULL
)

Arguments

dataset	Input dataset The variables specified by the by_vars, analysis_var, order, and keep_vars arguments are expected to be in the dataset.
dataset_ref	Expected observations dataset Data frame with all the combinations of PARAMCD, PARAM, AVISIT, AVISITN, ... which are expected in the dataset is expected.
by_vars	Grouping variables For each group defined by by_vars those observations from dataset_ref are added to the output dataset which do not have a corresponding observation in the input dataset or for which analysis_var is NA for the corresponding observation in the input dataset. Permitted Values: list of variables created by exprs() e.g. exprs(USUBJID, VISIT)
analysis_var	Analysis variable. Default: AVAL Permitted Values: a variable
order	Sort order The dataset is sorted by order before carrying the last observation forward (e.g. AVAL) within each by_vars. For handling of NAs in sorting variables see Sort Order.
keep_vars	Variables that need carrying the last observation forward Keep variables that need carrying the last observation forward other than analysis_var (e.g., PARAMN, VISITNUM). If by default NULL, only variables specified in by_vars and analysis_var will be populated in the newly created records.

Details

For each group (with respect to the variables specified for the by_vars parameter) those observations from dataset_ref are added to the output dataset

• which do not have a corresponding observation in the input dataset or

• for which analysis_var is NA for the corresponding observation in the input dataset.

  For the new observations, analysis_var is set to the non-missing analysis_var of the previous observation in the input dataset (when sorted by order) and DTYPE is set to "LOCF".

Value

The input dataset with the new "LOCF" observations added for each by_vars. Note, a variable will only be populated in the new parameter rows if it is specified in by_vars.

Author(s)

G Gayatri

See Also

BDS-Findings Functions for adding Parameters/Records: default_qtc_paramcd(), derive_expected_records(), derive_extreme_event(), derive_extreme_records(), derive_param_bmi(), derive_param_bsa(), derive_param_computed(), derive_param_doseint(), derive_param_exist_flag(), derive_param_exposure(), derive_param_framingham(), derive_param_map(), derive_param_qtc(), derive_param_rr(), derive_param_wbc_abs(), derive_summary_records()

Examples

library(dplyr)
library(tibble)

advs <- tribble(
  ~STUDYID,  ~USUBJID,      ~PARAMCD, ~PARAMN, ~AVAL, ~AVISITN, ~AVISIT,
  "CDISC01", "01-701-1015", "PULSE",        1,    61,        0, "BASELINE",
  "CDISC01", "01-701-1015", "PULSE",        1,    60,        6, "WEEK 6",
  "CDISC01", "01-701-1015", "DIABP",        2,    51,        0, "BASELINE",
  "CDISC01", "01-701-1015", "DIABP",        2,    50,        2, "WEEK 2",
  "CDISC01", "01-701-1015", "DIABP",        2,    51,        4, "WEEK 4",
  "CDISC01", "01-701-1015", "DIABP",        2,    50,        6, "WEEK 6",
  "CDISC01", "01-701-1015", "SYSBP",        3,   121,        0, "BASELINE",
  "CDISC01", "01-701-1015", "SYSBP",        3,   121,        2, "WEEK 2",
  "CDISC01", "01-701-1015", "SYSBP",        3,   121,        4, "WEEK 4",
  "CDISC01", "01-701-1015", "SYSBP",        3,   121,        6, "WEEK 6",
  "CDISC01", "01-701-1028", "PULSE",        1,    65,        0, "BASELINE",
  "CDISC01", "01-701-1028", "DIABP",        2,    79,        0, "BASELINE",
  "CDISC01", "01-701-1028", "DIABP",        2,    80,        2, "WEEK 2",
  "CDISC01", "01-701-1028", "DIABP",        2,    NA,        4, "WEEK 4",
  "CDISC01", "01-701-1028", "DIABP",        2,    NA,        6, "WEEK 6",
  "CDISC01", "01-701-1028", "SYSBP",        3,   130,        0, "BASELINE",
  "CDISC01", "01-701-1028", "SYSBP",        3,   132,        2, "WEEK 2"
)


# A dataset with all the combinations of PARAMCD, PARAM, AVISIT, AVISITN, ... which are expected.
advs_expected_obsv <- tribble(
  ~PARAMCD, ~AVISITN, ~AVISIT,
  "PULSE",         0, "BASELINE",
  "PULSE",         6, "WEEK 6",
  "DIABP",         0, "BASELINE",
  "DIABP",         2, "WEEK 2",
  "DIABP",         4, "WEEK 4",
  "DIABP",         6, "WEEK 6",
  "SYSBP",         0, "BASELINE",
  "SYSBP",         2, "WEEK 2",
  "SYSBP",         4, "WEEK 4",
  "SYSBP",         6, "WEEK 6"
)

derive_locf_records(
  dataset = advs,
  dataset_ref = advs_expected_obsv,
  by_vars = exprs(STUDYID, USUBJID, PARAMCD),
  order = exprs(AVISITN, AVISIT),
  keep_vars = exprs(PARAMN)
)

admiral documentation built on June 22, 2024, 9:06 a.m.