R/calc_dosing_weight.R

In clinPK: Clinical Pharmacokinetics Toolkit

#' Calculate commonly used "dosing weight" 
#' 
#' Dosing weight is determined based on total (TBW), ideal (IBW), or 
#' adjusted (ABW) body weight in kg.
#' 
#' This is derived using following:
#' - In principle, use IBW
#' - If total body weight (TBW) > 1.2*IBW, then use ABW
#' - If TBW < IBW, use TBW
#' @param weight weight
#' @param height height
#' @param sex sex
#' @param age age
#' @param verbose verbosity (`TRUE` or `FALSE`)
#' @param ... pased to `calc_abw()` function
#' @return Returns a list of the following elements:
#' \item{value}{Dosing weight, in units of kg}
#' \item{unit}{Units of dosing weight (kg)}
#' \item{type}{Type of dosing weight selected, e.g., total body weight, ideal body weight.}
#' @export
#' @examples
#' calc_dosing_weight(weight = 50, height = 170, sex = "female", age = 50)
calc_dosing_weight <- function(weight, height, age, sex, verbose = TRUE, ...) {
  if(is.null(weight) || is.null(height) || is.null(age) || is.null(sex)) {
    stop("Dosing weight calculation requires weight, height, age, and sex.")
  }
  ibw <- calc_ibw(weight = weight, height = height, age = age, sex = sex)
  abw <- calc_abw(weight = weight, ibw = ibw, ...)
  wt_chosen <- ibw
  weight_type <- "Ideal BW"
  if(weight > (ibw * 1.2)) {
    weight_type <- "Adjusted BW"
    wt_chosen <- abw
    if(verbose) message("Using adjusted body weight.")
  } else if(weight < ibw) {
    weight_type <- "Total BW"
    wt_chosen <- weight
    if(verbose) message("Using total body weight.")
  } else {
    if(verbose) message("Using ideal body weight.")
  }
  return(list(value = wt_chosen, unit = "kg", type = weight_type))
}