The main outcome measure for safety was the risk ratio for
minor and major harm for ibuprofen vs acetaminophen
treatment. We defined minor harm as the occurrence of an
adverse event not leading to withdrawal from the study (eg,
nausea, sweating, or cutaneous rash).35 The risk ratio for
minor harm was computed by dividing the number of minor
harm events per patient for the ibuprofen treatment arm
by the corresponding figure for the acetaminophen treatment
arm.
We defined major harm as the withdrawal of a patient from
the study owing to an adverse event (eg, abdominal pain, vomiting,
or hypothermia).35 The risk ratio for major harm was computed
by dividing the proportion of patients experiencing major
harm in the ibuprofen treatment arm by the corresponding
proportion in the acetaminophen treatment arm. We also computed
risk ratios for minor and major harm for each drug compared
with placebo