st: Question: Which ICD9 diagnoses occur first for each patient.

[Carl Severson <carlseverson@gmail.com>]

Hi,

I have data structured as follows:

Patient_ID    ICD9_Code    Date
    123               209.1        01/01/1987
    123               145           11/29/1990
    123               V46.3        08/04/1991
    123               89.7          09/08/1991
    451               V09.1        02/20/2010
    451               008           02/28/2010
    451               230.1        10/13/2012
    451               534           11/01/2012
    451               908           11/30/2012
    451               029.8         01/02/2013

I need a method of determining whether or not certain ICD9 codes occur
before or after other ICD9 codes for each patient.

For instance, for each patient, do ICD9 codes corresponding to
substance use diagnoses occur before or after ICD9 codes corresponding
to mental health diagnoses.

Is there some built in functions that I am not aware of that will let
me do this in STATA? I have been unable to find them if there is. Or
am I going to have to get down and dirty with MATA?

Any help or advice would be greatly appreciated.

Thanks,
Carl Severson
*
*   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/