Re: T in $DES
The question has been answered correctly by the various people who commented
recently.
Dennis asked me to "explain the inner workings."
This topic has been discussed in the past. See the mail archive web site
https://www.mail-archive.com/[email protected]
A good search is for "Warning 48". This will bring up a number of emails re:
"Question regarding Calculation Process in $DES BLOCK"
You will find a discussion of the issue in these emails, from June 2011.
Quoted reply history
On Tue, Jul 6, 2021, at 7:28 AM, Dennis Fisher wrote:
> Matts
>
> I believe that the issue that you encountered is addressed in the NONMEM
> output. Look for this text:
>
> (WARNING 48) DES−DEFINED ITEMS ARE COMPUTED ONLY WHEN EVENT TIME
> INCREASES. E.G., DISPLAYED VALUES ASSOCIATED WITH THE FIRST EVENT RECORD
> OF AN INDIVIDUAL RECORD ARE COMPUTED WITH (THE LAST ADVANCE TO) AN EVENT
> TIME OF THE PRIOR INDIVIDUAL RECORD.
>
> The wording is arcane but the basic message is that, for each subject, the
> first values for DES computed entries are not what you expect.
> Despite this, NONMEM is "doing the right thing".
> I defer to Alison Boeckmann to explain the inner workings.
>
> Dennis
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone / Fax: 1-866-PLessThan (1-866-753-7784)
> www.PLessThan.com http://www.plessthan.com/
>
>
>
>> On Jul 6, 2021, at 5:44 AM, Matts Kågedal <[email protected]> wrote:
>>
>> Hi all,
>> I have a question regaring T in $DES.
>> I have a time-varying covariate that is derived based on an explicit
>> equation and then use in a differential equation.
>> I got some funny results in the output table and investigated a bit further.
>>
>> I therefore derived T_DAY=T in $DES as below and output it in $TABLE.
>> Why is T_DAY at TIME=0 equal to the time of the last observation for the
>> patient? I was expecting it to be Zero (same as Time). Seems to be the same
>> for all IDs in the dataset.
>> Below is the output created in $TABLE including the "derived" variable T_DAY.
>> Any advice would be appreciated.
>> Matts Kågedal
>>
>> <image.png>
>>
>> <image.png>
--
Alison Boeckmann
[email protected]