I'm back from being way behind in Digests, so I may have missed a few, but I
had to jump into this discussion about "I'm healthy and I was..."  I try
very hard to do a bit of education with regard to the concept of "relative
risk"  and "odds ratios".  It is usually the first epidemiology mini-course
for most people.  I explain that we all know and now accept that smoking
causes cancer (85-90% of lung cancer is in smokers), but not every smoker
will get cancer (about 1 in 9 will).  They (even smokers--except perhaps my
father in-law who thinks it is all a plot from the public health and medical
communities) can understand this.  Then, I describe how this works with just
about anything to which you want to attribute risk.  So, take a population
of "exposed" persons (formula) and a population of "unexposed"
(breastfed=normal state).  Then, with all other characteristics being held
constant (either through pairwise allocation, or stratified analysis, or
statistical manipulations such as multiple regression)  one then compares
the "disease" in each of the groups.  With this, one can find out what the
RATE  is (rates always have denominators because of this).

Going back to the smoker example in a very simplified manner, the lung
cancer rate for smokers might be 1/9 whereas for nonsmokers the lung cancer
rate might be 1/200 (I'm guestimating on this last number so don't hold me
to it).  Comparing these rates gives you a "relative risk ratio".  In my
example, smokers have 22 TIMES the risk of lung cancer compared to
nonsmokers (again, it is the procedure not the precise numbers I want to
illustrate).  The other way of saying the exact same thing is to say that
"nonsmokers have 4.5% the risk of smokers for developing lung cancer (you
could also say 1/22 th the risk).   We can go on to compare all sorts of
disease states for formula fed vs breastfed infants.  Keep in mind that HOW
you say these (which referrant group one usese) makes a big difference in
the impact of the message.
Any questions?
--
--Chris Hafner-Eaton, PhD, MPH, CHES, IBCLC    [log in to unmask]
INFANT CUISINE AND MOTHER CARE: Lactation Consulting, Perinatal Health
Education and Attachment Parenting Classes for parents and practitioners

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