correct.conc: Correct Missing Concentration
In qpNCA: Noncompartmental Pharmacokinetic Analysis by qPharmetra

Description Usage Arguments Details Value Examples

Corrects missing concentration at critical time points (e.g, predose, TAU, start and end of user selected AUC interval).

correct.conc(
  x,
  by = character(0),
  nomtimevar = "ntad",
  tau = NA,
  tstart = NA,
  tend = NA,
  teval = NA,
  th = NA,
  reg = "SD",
  ss = "N",
  route = "EV",
  method = 1
)

`x`	input dataset name (after Time Deviation Correction Rules have been applied by `correct.time`)
`by`	column names in x indicating grouping variables
`nomtimevar`	variable name containing the nominal sampling time after dose
`tau`	dosing interval (for multiple dosing); NA (default) for if single dose; x$tau overrides
`tstart`	start time of partial AUC (start>0); NA (default) if not requested; x$tstart overrides
`tend`	end time of partial AUC; NA (default) if not requested; x$tend overrides
`teval`	user selected AUC interval; NA (default) if not requested; x$teval overrides
`th`	lamdba_z information for each curve; like output of `est.thalf`
`reg`	regimen, "sd" or "md"; x$reg overrides
`ss`	is steady state reached (y/n); x$ss overrides
`route`	route of drug administration ("EV","IVB","IVI"); x$route overrides
`method`	method for trapezoidal rule; x$method overrides 1: linear up - linear down 2: linear up - logarithmic down 3: linear before first Tmax, logarithmic after first Tmax

Use interpolation if there is a measurable concentration BEFORE and AFTER the missing concentration
Use extrapolation if there is NO measurable concentration AFTER the missing concentration
Set missing concentration at predose to 0 (SD, non-endogenous) or value at t=TAU (steady state only)
Set missing concentration at t=TAU to value at t=0 (steady state only)

The following Concentration Deviation Correction Rules will be applied to critical time points (t=0, tau, tstart, tend, teval), if needed:

Rule	Regimen	Description	Applied to
SDC-1	sd	Set concentration to 0 (only non-endogenous compounds)	t=0
SDC-2	sd	impute missing concentration by interpolation	t=tau,tstart,tend,teval
SDC-3	sd	impute missing concentration by extrapolation	t=tau,tend,teval
SDC-4	sd (IVB)	impute missing concentration by back-extrapolation	t=0
MDC-1	md	impute missing concentration by existing conc at t=0 or t=tau (only if steady state has been reached)	t=0,tau
MDC-2	md	impute missing concentration by interpolation	t=tau,tstart,tend,teval
MDC-3	md	impute missing concentration by extrapolation	t=tau,tend,teval
MDC-4	md (IVB)	impute missing concentration by back-extrapolation	t=0

a dataset with missing concentrations imputed. The following variables are added:

Variable	Description
crule.nr	correction rule number
crule.txt	text explaining what was altered
applies.to.conc	lists all critical time points to which the concentration correction rule applies

example(correct.time)
x %<>% mutate(ss = 'N', route = 'EV')
# route redefined for completeness
x %<>% correct.conc(by = 'subject') # ignoring th
x %>% head