A randomised controlled trial on the effectiveness of bracing patients with idiopathic scoliosis: failure to include patients and lessons to be learnt.

Trials often do not succeed in including as many patients as anticipated beforehand. The aim of this paper was to describe why we were not able to include more than a few patients in our randomized controlled treatment trial on the effectiveness of bracing patients with idiopathic scoliosis, and to describe which lessons can be learnt. A pilot study on the willingness to participate in such a trial was conducted amongst 21 patients and their parents. A description of how we prepared and designed this trial, the problems we faced and how we tried to improve the inclusion are given. A total of four patients were included, and 14 refused to participate in an 18-month period. There were a lot less eligible patients than anticipated (40 instead of 100 per year), and the patients' participation rate was much lower than we had found in our pilot study (21% instead of 70%). The trial failed to include more than a few patients because of an overestimation of the number of eligible patients and because a lot less eligible patients were willing to participate compared to our pilot study. One reason for a low participation rate could be that this trial evaluated a frequently used existing treatment instead of a new treatment, and patients and parents might be afraid of not being treated (despite an intensive secure system for the control arm).