The role of sex in sample size determination.

Abstract

The sample size calculation in randomized clinical trials mainly depends on the incidence of the outcome measure in the control group. Sample size calculation should also take into account the differences in outcome rates between male vs. female genders. This issue is, however, often not considered, leading to over- or under-estimation of the outcome distribution and ultimately to underpowered trials with erroneous conclusions. Hence, this short article discusses examples related gender and sample size and provides indications for an optimal estimation.