Re: {MEDSTATS} statistical cut point

[Peter Flom]

Paul

I think the first thing to consider is what you are trying to determine. I think it's not so much what proportion of the patients are intoxicated, rather, it's what proportion of the time the clinical judgment gives a false negative. Fortunately, you have what might be a good test sample. Can you record clinical judgment on a sample from the hospital that DOES do alcohol and blood tests? Then you could see how often judgment disagrees with tests.

If it is common, then perhaps you could adjust clinical judgment - e.g. what if two clinicians had to rate the person, and only if both said "not intoxicated" would you include that person?

Peter



-----Original Message-----
>From: "Swank, Paul R" <Paul.R...@uth.tmc.edu>
>Sent: Dec 8, 2009 11:03 AM
>To: "meds...@googlegroups.com" <meds...@googlegroups.com>
>Subject: {MEDSTATS} statistical cut point
>
>
>I have been asked to suggest a statistical solution for a problem. The problem is that we are taking ER patients with a mild traumatic brain injury for a research study. Someone has raised an issue about patients who may be intoxicated upon admission. One hospital says they routinely do alcohol and drug tests but the other does not. It has been suggested that we use clinical judgment and then do a follow-up screen after we get consent. Then if we find that a "significant" number of patients are getting recruited who were intoxicated (say 10% or more of the first 20 patients) then we rethink this. Someone else suggested the statistician (that's me) come up with a statistical solution. I know that the confidence intervals for 2 out of 20 (10%) are pretty wide, like 1%-30%, so this doesn't seem like a good statistical solution. I think it should be clinical decision but I am open to a reasonable statistical solution if someone has one.
>
>Paul
>
>Dr. Paul R. Swank,
>Professor and Director of Research
>Children's Learning Institute
>University of Texas Health Science Center-Houston
>
>
>
>>


Peter L. Flom, PhD
Statistical Consultant
Website: www DOT peterflomconsulting DOT com
Writing; http://www.associatedcontent.com/user/582880/peter_flom.html
Twitter: @peterflom

[Swank, Paul R]

Thanks Peter.

Paul

Dr. Paul R. Swank,
Professor and Director of Research
Children's Learning Institute
University of Texas Health Science Center-Houston