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Re: st: Modelling two binary outcomes that are not mutually exclusive


From   Dr Murray Finkelstein <[email protected]>
To   [email protected]
Subject   Re: st: Modelling two binary outcomes that are not mutually exclusive
Date   Sat, 27 Nov 2004 10:41:12 -0500

I am surprised to see that the beginning of the first sentence of my original message was somehow cut off: The message was :

"From a clinical perspective using a binary classification seems a little suspect since symptoms of depression and anxiety often appear together (and the pharmaceutical companies make a big deal of medications to treat these "comorbidities"). If you had continuous measures, you could generate a Depression-Anxiety Index. Failing that, I would favour a third category for the "mixed" disorder. "


Dr Murray Finkelstein wrote:


little suspect since symptoms of depression and anxiety often appear together (and the pharmaceutical companies make a big deal of medications to treat these "comorbidities"). If you had continuous measures, you could generate a Depression-Anxiety Index. Failing that, I would favour a third category for the "mixed" disorder.

Ron�n Conroy wrote:


I have two binary outcomes, measured in a patient population (anxiety and depression). For various reasons, I suspect that a number of patient characteristics predict depression but not anxiety.

If the two diagnoses were mutually exclusive, all would be well. I could use multinomial logistic regression and compare the coefficients. However, there is about a 20% overlap. Is this a Known Problem? I could model the overlap category as a third outcome, and show that the coefficients were similar to those for depression alone and different to those for anxiety alone, but this is slicing the sample a little thin - there are just 8 people with both disorders. (This approach actually works, sort of, given the small numbers, so I'm on the right track from the theory point of view.)

Any suggestions out there?


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|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| Murray M Finkelstein PhD MD CCFP | Department of Family and Community Medicine | University of Toronto Mt Sinai Hospital, Suite 413 600 University Avenue Toronto, Ontario Canada M5G 1X5 Phone: 416-326-7879
FAX: 416-326-7761 E-mail: [email protected]

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