# \[e-drug\] Asthma associated with early antibiotic use (cont'd)

**URL:** <https://talk.edrugplus.org/t/e-drug-asthma-associated-with-early-antibiotic-use-contd/18380>\
**Category:** e-drug\
**Created:** [December 9, 2003, 9:35pm UTC](https://talk.edrugplus.org/t/e-drug-asthma-associated-with-early-antibiotic-use-contd/18380 "2003-12-09T21:35:42Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Christine\_Johnson](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@Christine\_Johnson](https://talk.edrugplus.org/u/Christine_Johnson)\
**Post date:** [December 9, 2003, 9:35pm UTC](https://talk.edrugplus.org/t/e-drug-asthma-associated-with-early-antibiotic-use-contd/18380/1 "2003-12-09T21:35:42Z")

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E-drug: Asthma associated with early antibiotic use (cont'd)  
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[A while ago we had a discussion on asthma associated with early  
antibiotic use. I contacted Chris Johnson, the author, and  
asked her whether she could elaborate on her methodology, as  
some of us wondered whether the study had been adequately  
controlled. Her answer is below. HH]

Dear E-druggers,

Sorry to be so late with this response--it was in my mail-in-progress  
folder and I forgot to mail it--

Yes, we controlled and/or stratified by child's gender, first-born  
status, pet ownership, breast-feeding, maternal history of allergy or  
asthma, day care use, lower respiratory infections and occurrence  
of fever (first year). We eventually dropped gender, firstborn and  
day care from the model as it helped increase our statistical power  
and didn't materially change the estimates.

All the children were suburban whites.

We also repeated the analyses dropping kids who received  
antibiotics in the first six months for any respiratory symptoms in  
order to address the "reverse causation" bias--which didn't change  
the estimates.

Timing seems to be important (not surprisingly). Repeating these  
analyses considering 12 months or 2 years as the exposure period  
pretty much wiped out any associations.

Chris Johnson  
e-mail: cjohnso1@hfhs.org

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