RT Journal
A1 Beerepoot M, ter Riet G, Geerlings SE
T1 Lactobacilli vs antibiotics to prevent recurrent urinary tract infections: An inconclusive, not inferior, outcome—reply
JF Archives of Internal Medicine
JO Archives of Internal Medicine
YR 2012
FD November 26
VO 172
IS 21
SP 1690
OP 1694
DO 10.1001/2013.jamainternmed.111
UL http://dx.doi.org/10.1001/2013.jamainternmed.111
AB 
As far as we are aware, there are no validated rules to determine noninferiority margins. Nor can there be, since almost every clinical situation has its own peculiarities. What constitutes a clinically acceptable difference is ultimately a matter of judgment and may vary across patients, physicians, investigators, regulators, or payers.1 It is striking but perhaps not surprising that in trial registrations of noninferiority trials, the noninferiority margins are very often absent.2 A rational approach to planning noninferiority trials would involve performing a cost-utility analysis to derive the noninferiority margins before embarking on the trial. Such analyses could incorporate the different opinions of the various stakeholders.