I am still picking through the details of the Schanler study having my curiousity aroused enough to 
spend the $12 to get a copy of the article.  I looked carefully at Table 2.  The authors say that they 
expected a higher rate of NEC.  Hence the authors designed this study to have had an adequate 
sample size to detect a difference of 30% in the PF (preterm formula) versus 55% in the MM 
(fortified mother's milk) and the DM (pasteurized donors milk) groups.  

The rates of NEC were 11% in the PF group, versus 6% in the DM and 6% in the MM group.  This is 
almost a 50% difference.  That is not a trivial difference.  Because the rates of NEC much less than 
they predicted, the sample sizes are completely inadequate to detect this difference.  Hence, 
statistically, they can reach no conclusions whatsoever.  They simply did not have the statistical 
power to deal with such lower percentages.  NOT because they didn't design the study well, but 
because the unexpected happened.  You can NOT make a conclusion about a negative result 
unless you have adequate statistical power for the prevalence of the condition you are 
investigating.  So, who knows what would have happened if they had a larger sample!   It could 
very well have showed a statistically significant difference or maybe that apparent difference was 
total chance.  No one can say with any certainty.  I'm surprised a statistician did not catch this 
problem.  I'm too tired to do the sample size calculations, but they would have need more than 
double the numbers at the rates of NEC and LOS they were observing in these groups to have 
detected anything.

Even when they clumped the LOS and the NEC together you see a difference also makes one 
wonder what would have happened with a larger sample.  Heres that "severity issue"!  You don't se 
much diference between the percent that had 1 episode PF = 23%, DM = 29% & MM =26%.  But if 
you look at the more than 1 episode you get PF=16%, DM = 10% & MM = 2%.  Looks like a 
possible dose response from formula to mother's milk with donor milk in the middle.  But who can 
tell without the sample size being large enough?  One cannot say anything either for or against an 
effect with this sample size.

Really, with the seriousness of these conditions (and if I had unlimited funds with which to hire 
researchers), I would have done a much larger sample size to detect much smaller differences 
between the groups.  I would think a 5% or 10% difference would be enough to worry a parent, 
much less the 25% difference they picked for their sample size calculations.  Its such a shame 
because this was clearly a very expensive and tedious study to conduct.  They really worked out a 
lot of details.  I'm sure the sample sizes I would have picked would have quadrupled the costs taht 
probably were high to begin with.   

I just went through a menigitis scare with my son where he was exposed at camp.  One look at 
that 15% death rate on the CDC website pushed me from my rationale brain that he really had no 
reason to share saliva or food with the girl in his group to "No way I'm allowing my kid to have any 
risk of death".  So, he was almost certainly unnecessarily prophylactically treated because my 
mommy brain took over.

I'm hoping that there will be more who might want to work on this issue in more depth before we 
throw the donor mik out with the bath water.  And not just look at whether or not it is the better 
choice, but under what conditions!  

Best regards, Susan Burger

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