Iron deficiency anemia (IDA) is one of the bread-and-butter conditions pediatricians
manage. At first glance, it's easy to treat - just give some iron - but of course,
nothing is easy in medicine! In particular, nonadherence to medication, often due
to unpleasant side effects, is a problem. The authors compared 2 different approaches:
use of the traditional oral ferrous sulfate drops versus oral iron polysaccharide
complex drops. The latter in theory has better tolerability due to better taste.
Eighty infants 9 - 28 months of age were enrolled, with outcome analysis showing statistically
significant improvements in mean hemoglobin increase and in numbers of children with
complete resolution of IDA in favor of the old standby, ferrous sulfate drops. Rates
of resolution of IDA were 29% for ferrous sulfate and 6% for the iron polysaccharide
product, giving a number needed to treat (NNT) of about 4.* Tolerability and adherence
slightly favored the iron polysaccharide group but did not reach statistical significance.
So far, pretty good. However, I (and the authors) would argue that these findings
might not work exactly the same way in everyday clinical care, and the authors tell
us why in their discussion of 4 study limitations.
First, only 1 clinical site was involved, which always raises concerns about the generalizability
of results. Second, a lot of these kids had severe anemia, even some requiring blood
transfusion. Is that a different patient population than seen in general pediatric
practice, which usually deals with milder disease? If so, pediatricians in practice
may not see the same results. Third, about a quarter of the subjects didn't complete
the planned 12 week follow-up period. Though this was exactly the attrition rate predicted
by the investigators before starting the study, it's a large dropout rate and could
affect study validity. Finally, like most funded RCTs, the children and families had
close follow-up and monitoring by study personnel, a luxury not available in the real
In spite of these limitations, the old standby ferrous sulfate didn't fare badly.
*NNT is the reciprocal of the absolute risk reduction, in this case (1/(0.29-0.06))
X 100. Translating to words for the results of the study above, for every 4 infants
treated with ferrous sulfate rather than iron polysaccharide, 1 additional infant
would achieve complete resolution of IDA. As NNT goes, that's a pretty high return
on investment. (BTW, I'm a little annoyed that the authors and JAMA editors made me
calculate this on my own, rather than providing it in the article!)