Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
st: Re: brace counting for person-time
From
Nabarun Dasgupta <[email protected]>
To
<[email protected]>
Subject
st: Re: brace counting for person-time
Date
Sun, 03 Mar 2013 22:58:50 -0500
Of course the answer comes to you after you reach out.
The solution that is working for me:
1. Convert ender to 1/-1 instead of 0/1 and use sum() to create a running
total
2. Figure out the number of NON-EXPOSED days (including ends of the month)
using the running total
3. Subtract from the known number of days in the month
On 3/2/13 5:26 PM, Nabarun Dasgupta typed:
>
>
>Dear STATALIST:
>
>I would greatly appreciate your help and haven't seen exactly what I need
>in the archive. I am trying to count the person-days exposed for a single
>patient in a given month over multiple overlapping Rx records. The correct
>number of days exposed is 26 in the example data below. I tried a "brace
>counting" approach, so the variable _ender_ is zero at the start of the Rx
>period, and one for the last day of the period. Hence there are eight
>records for four prescriptions. One solution would be to calculate the
>days in between each _bracedate_ and only add up the unique days between
>braces, but I can't figure out how to create a counter that identifies
>only the exposed periods. Note that rxno 5061 was only for one day, making
>things trickier.
>
>
>
>start stop rxno ender bracedate
>5-Jan-11 12-Jan-11 2248 0 5-Jan-11
>12-Jan-11 26-Jan-11 3645 0 12-Jan-11
>5-Jan-11 12-Jan-11 2248 1 12-Jan-11
>19-Jan-11 30-Jan-11 2261 0 19-Jan-11
>25-Jan-11 25-Jan-11 5061 0 25-Jan-11
>25-Jan-11 25-Jan-11 5061 1 25-Jan-11
>12-Jan-11 26-Jan-11 3645 1 26-Jan-11
>19-Jan-11 30-Jan-11 2261 1 30-Jan-11
>
>
>Generalized schematic of the brace counting approach is below, but I am
>open to other solutions. Creating a dummy variable for each date and using
>0,1 is not an option as far as I can tell because of the number of
>prescription records (55 million) and length of time (3 years).
>
>
>
>Overlapping intervals:
>
> (-------------------)
> (----------------------)
> (---)
> (---------------------)
> (-----------------)
>
> Consolidated:
>
> (-----(-------------)-(-----)----------------) (----(---)--------)
>
>
>
>Your help is genuinely appreciated!
>
>Best,
>Nabarun
>
>-----
>Nabarun Dasgupta
>Department of Epidemiology
>Gillings School of Global Public Health
>& Injury Prevention Research Center
>University of North Carolina
>Chapel Hill, NC 27599 USA
>
>
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/