extract_bmi: Extract most recent BMI score relative to an index date.

In rcprd: Extraction and Management of Clinical Practice Research Datalink Data

Extract most recent BMI score relative to an index date.

Description

Extract most recent BMI score relative to an index date.

Usage

extract_bmi(
  cohort,
  varname = NULL,
  codelist_bmi = NULL,
  codelist_weight = NULL,
  codelist_height = NULL,
  codelist_bmi_vector = NULL,
  codelist_weight_vector = NULL,
  codelist_height_vector = NULL,
  indexdt,
  t = NULL,
  t_varname = TRUE,
  time_prev = 365.25 * 5,
  time_post = 0,
  lower_bound = -Inf,
  upper_bound = Inf,
  db_open = NULL,
  db = NULL,
  db_filepath = NULL,
  out_save_disk = FALSE,
  out_subdir = NULL,
  out_filepath = NULL,
  return_output = TRUE
)

Arguments

cohort	Cohort to extract age for.
varname	Optional name for variable in output dataset.
codelist_bmi	Name of codelist (stored on hard disk in "codelists/analysis/") for BMI to query the database with.
codelist_weight	Name of codelist (stored on hard disk in "codelists/analysis/") for weight to query the database with.
codelist_height	Name of codelist (stored on hard disk in "codelists/analysis/") for height to query the database with.
codelist_bmi_vector	Vector of codes for BMI to query the database with.
codelist_weight_vector	Vector of codes for weight to query the database with.
codelist_height_vector	Vector of codes for height to query the database with.
indexdt	Name of variable which defines index date in cohort.
t	Number of days after index date at which to calculate variable.
t_varname	Whether to add t to varname.
time_prev	Number of days prior to index date to look for codes.
time_post	Number of days after index date to look for codes.
lower_bound	Lower bound for returned values.
upper_bound	Upper bound for returned values.
db_open	An open SQLite database connection created using RSQLite::dbConnect, to be queried.
db	Name of SQLITE database on hard disk (stored in "data/sql/"), to be queried.
db_filepath	Full filepath to SQLITE database on hard disk, to be queried.
out_save_disk	If TRUE will attempt to save outputted data frame to directory "data/extraction/".
out_subdir	Sub-directory of "data/extraction/" to save outputted data frame into.
out_filepath	Full filepath and filename to save outputted data frame into.
return_output	If TRUE will return outputted data frame into R workspace.

Details

BMI can either be identified through a directly recorded BMI score, or calculated via height and weight scores. Full details on the algorithm for extracting BMI are given in the vignette: Details-on-algorithms-for-extracting-specific-variables. This vignette can be viewed by running vignette("help", package = "rcprd").

Specifying db requires a specific underlying directory structure. The SQLite database must be stored in "data/sql/" relative to the working directory. If the SQLite database is accessed through db, the connection will be opened and then closed after the query is complete. The same is true if the database is accessed through db_filepath. A connection to the SQLite database can also be opened manually using RSQLite::dbConnect, and then using the object as input to parameter db_open. After wards, the connection must be closed manually using RSQLite::dbDisconnect. If db_open is specified, this will take precedence over db or db_filepath.

If out_save_disk = TRUE, the data frame will automatically be written to an .rds file in a subdirectory "data/extraction/" of the working directory. This directory structure must be created in advance. out_subdir can be used to specify subdirectories within "data/extraction/". These options will use a default naming convetion. This can be overwritten using out_filepath to manually specify the location on the hard disk to save. Alternatively, return the data frame into the R workspace using return_output = TRUE and then save onto the hard disk manually.

Specifying the non-vector type codelists requires a specific underlying directory structure. The codelist on the hard disk must be stored in "codelists/analysis/" relative to the working directory, must be a .csv file, and contain a column "medcodeid", "prodcodeid" or "ICD10" depending on the chosen tab. The input to these variables should just be the name of the files (excluding the suffix .csv). The codelists can also be read in manually, and supplied as a character vector. This option will take precedence over the codelists stored on the hard disk if both are specified.

Value

A data frame with variable BMI.

Examples

## Connect
aurum_extract <- connect_database(file.path(tempdir(), "temp.sqlite"))

## Create SQLite database using cprd_extract
cprd_extract(aurum_extract,
filepath = system.file("aurum_data", package = "rcprd"),
filetype = "observation", use_set = FALSE)

## Define cohort and add index date
pat<-extract_cohort(system.file("aurum_data", package = "rcprd"))
pat$indexdt <- as.Date("01/01/1955", format = "%d/%m/%Y")

## Extract most recent BMI prior to index date
extract_bmi(cohort = pat,
codelist_bmi_vector = "498521000006119",
codelist_weight_vector = "401539014",
codelist_height_vector = "13483031000006114",
indexdt = "indexdt",
time_prev = Inf,
db_open = aurum_extract,
return_output = TRUE)

## clean up
RSQLite::dbDisconnect(aurum_extract)
unlink(file.path(tempdir(), "temp.sqlite"))

rcprd documentation built on April 12, 2025, 1:57 a.m.