NextDose: A web-based Bayesian dose forecasting tool

Last updated 28 April 2024

Observation Types

The NextDose Doses and Observations window is used to enter doses and individual observations such as weight. Observation types such as weight are associated with a date and time so that time varying changes in these observations may be used by the NextDose model.

There are also observation types that are not time sensitive. They can be associated with any date and time and have an effect across the full time sensitive dosing and observation history.

AUC Occ

The AUC Occ observation calculates the area under the curve (AUC) after each dose until the time of the next dose (a dosing occasion) based on the predicted individual concentration shown in the graph on the Results page. The AUC following the last dose is calculated until the end of the predicted individual concentration display. The measurement box should be set to a value of 1 to activate this observation type.

The AUC associated with for each dose and associated individual CL/F value is displayed as AUC inf alongside the AUC occ value. The ratio of AUC occ to AUC inf gives an indication of how close AUC occ is approaching the steady state AUC during the dosing occasion.

AUC T1

The AUC T1 observation calculates the area under the curve (AUC) of the predicted individual concentration from the AUC starting time (h) entered in the measured value box. If the starting time is set to “.” the value will be calculated from the date and time of the observation. The time in hours is counted from the time of the first dose in the Doses and Observations window. If this is set to 0 h, this will measure from the time the first dose, either an oral dose, an IV bolus dose or start of an IV infusion dose. If the AUC starting time is set to 24 h then it will measure from 24 hours after the time of the first dose.

AUC T2

The AUC T2 observation calculates AUC from the AUC starting time in AUC T1 and ending at the user specified time (h) entered in the AUC T2 measured value box. If the starting time is set to “.” the value will be calculated from the date and time of the observation. This should be set to a value greater than the AUC T1, otherwise no value for AUC is generated. Note that the date and time associated with the “AUC T2” observation is not used in calculating the AUC.

Hint: Use AUC occ to see the hours of doses as a guide for selection of AUC T1 and AUC T2. AUC T1 with AUC T2 takes precedence over AUC occ. Delete or ignore the AUC T1 and T2 observation types in order to use AUC occ.

Note: The AUC estimates calculated from the predicted individual concentration time course use a simple trapezoidal integration method with an error of around 1%.