I am looking for a short description explaining the terms "cohort
study", "odds ratio" and "hazard ratio". These terms are used in
medical research papers and im unsure what they mean.

Howdy lylemoncur-ga,

Here are some short descriptions of the terms in question.

SUNY Downstate Medical Center - Cohort Study
http://library.downstate.edu/ebm/2400.htm

"A Cohort Study is a study in which patients who presently have a certain
condition and/or receive a particular treatment are followed over time and
compared with another group who are not affected by the condition under
investigation."

Nature Clinical Practice - Hazard Ratio
http://www.nature.com/glossary/clinicalpractice/defDetails.do?uid=ncp_282

"The relative likelihood of experiencing a particular event; an HR of 0.5
indicates that one group has half the risk of the other group."

Bandolier - Odds Ratio
http://www.jr2.ox.ac.uk/bandolier/booth/glossary/Odds.html

"A ratio of the number of people incurring an event to the number of people
who have non-events."

If you need any clarification, please feel free to ask.


Search strategy: Google searches on the terms in question.

Looking Forward, denco-ga - Google Answers Researcher

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Request for Answer Clarification by lylemoncur-ga on 24 Oct 2006 13:28 PDT

Thanks very much, answer just what i was looking for. 
Would it be possible to find more information on Hazard Ratio. Would
like to know more about it is calculated and its clinical use?

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Clarification of Answer by denco-ga on 24 Oct 2006 13:51 PDT

Not a problem, lylemoncur-ga.

University of Arizona - Statistics
http://student.biology.arizona.edu/honors2002/group03/Statistics.htm

"For health risks that have a Hazard Ratio greater than one, it means that the
chances of getting that health risk increased with the treatment.  For health
risks that have a Hazard Ratio less than one, it means that the chances of
getting that health risk decreased with the treatment."

The above reference has a great table showing the use of Hazard Ratios within
clinical study results.

This Wikipedia article on Hazard Ratio goes into the calculations aspect.
http://en.wikipedia.org/wiki/Hazard_ratio

Because of the graphics it would be best for you to view the above page for
yourself.

As pointed out on the above Wikipedia page, you might want to read up on
Relative Risk as well.
http://en.wikipedia.org/wiki/Relative_risk

Looking Forward, denco-ga - Google Answers Researcher

Extremely helpful and quick response

Glad to have been of service, lylemoncur-ga, and thanks for the kind comments
and 5 star rating.

Looking Forward, denco-ga - Google Answers Researcher