Placebo comparator group selection and use in surgical trials: the ASPIRE project including expert workshop
Authors: Beard David J , Campbell Marion K , Blazeby Jane M , Carr Andrew J , Weijer Charles , Cuthbertson Brian H , Buchbinder Rachelle , Pinkney Thomas , Bishop Felicity L , Pugh Jonathan , Cousins Sian , Harris Ian , Lohmander L Stefan , Blencowe Natalie , Gillies Katie , Probst Pascal , Brennan Carol , Cook Andrew , Farrar-Hockley Dair , Savulescu Julian , Huxtable Richard , Rangan Amar , Tracey Irene , Brocklehurst Peter , Ferreira Manuela L , Nicholl Jon , Reeves Barnaby C , Hamdy Freddie , Rowley Samuel CS , Lee Naomi , Cook Jonathan A 
Published: September 2021

Background
The use of placebo comparisons for randomised trials assessing the efficacy of surgical interventions is increasingly being considered. However, a placebo control is a complex type of comparison group in the surgical setting and, although powerful, presents many challenges.

Objectives
To provide a summary of knowledge on placebo controls in surgical trials and to summarise any recommendations for designers, evaluators and funders of placebo-controlled surgical trials.

Design
To carry out a state-of-the-art workshop and produce a corresponding report involving key stakeholders throughout.

Setting
A workshop to discuss and summarise the existing knowledge and to develop the new guidelines.

Results
To assess what a placebo control entails and to assess the understanding of this tool in the context of surgery is considered, along with when placebo controls in surgery are acceptable (and when they are desirable). We have considered ethics arguments and regulatory requirements, how a placebo control should be designed, how to identify and mitigate risk for participants in these trials, and how such trials should be carried out and interpreted. The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Surgical placebos might be most appropriate when there is poor evidence for the efficacy of the procedure and a justified concern that results of a trial would be associated with a high risk of bias, particularly because of the placebo effect.

Conclusions
The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Feasibility work is recommended to optimise the design and implementation of randomised controlled trials. An outline for best practice was produced in the form of the Applying Surgical Placebo in Randomised Evaluations (ASPIRE) guidelines for those considering the use of a placebo control in a surgical randomised controlled trial.

Limitations
Although the workshop participants involved international members, the majority of participants were from the UK. Therefore, although every attempt was made to make the recommendations applicable to all health systems, the guidelines may, unconsciously, be particularly applicable to clinical practice in the UK NHS.

Future work
Future work should evaluate the use of the ASPIRE guidelines in making decisions about the use of a placebo-controlled surgical trial. In addition, further work is required on the appropriate nomenclature to adopt in this space.

Funding
Funded by the Medical Research Council UK and the National Institute for Health Research as part of the Medical Research Council–National Institute for Health Research Methodology Research programme.