I'm reading a paper for a journal club (Zinc Supplementation Reduces the
Incidence of Acute Lower Respiratory Infections in Infants and Preschool
Children: A Double-blind Controlled Trial, Sazawal S et al Pediatrics (July
19998), 102 (1) 1-5). They mention that the rate of acute lower respiratory
infections (ALRI) decreased from 0.35 episodes per child per year to 0.19.
If I calculate a number needed to treat (6.25), does this have any meaning?
It seems to me that this means that if we use zinc supplements, we will see
one fewer ALRI for every 6.25 patient years. Is this a valid statement? Or
can I only use the NNT for proportions?
Also, I assume that ALRI is seasonal (I'm not a doctor, so forgive my
naivete). If so, does this change the interpretation (e.g., 6.25 patient
years during the such and such a time period)?
Sorry if this is such a basic question. I have a background in Statistics,
but this NNT stuff is new to me.
Steve Simon, [log in to unmask], Standard Disclaimer.
STATS - Steve's Attempt to Teach Statistics: http://www.cmh.edu/stats
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|