Falling in the margin.

In a randomised controlled trial (RCT) we are usually trying to answer the question of which treatment is best. Sometimes, though, we may be considering a treatment that we do not believe will perform better than an existing option but has other benefits. For instance, it could be cheaper, easier to deliver or more acceptable to patients. For example, the need for urodynamic testing compared to simple office evaluation before stress incontinence surgery was evaluated in an RCT (Nager et al. N Engl J Med. 2012;366:1987-97). The authors believed simple office-based evaluation would be both less invasive than urodynamic testing and that it may also reduce the risk of urinary tract infections. It was also expected that simple office-based evaluation was unlikely to reduce treatment success.