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Feasibility of surgical randomised controlled trials with a placebo arm: a systematic review
  1. Karolina Wartolowska1,2,
  2. Gary S Collins2,3,
  3. Sally Hopewell2,3,
  4. Andrew Judge1,2,4,
  5. Benjamin J F Dean1,2,
  6. Ines Rombach1,2,
  7. David J Beard1,2,5,
  8. Andrew J Carr1,2,5
  1. 1Oxford NIHR Musculoskeletal Biomedical Research Unit, Oxford, UK
  2. 2Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Institute of Musculoskeletal Sciences, University of Oxford, Oxford, UK
  3. 3Centre for Statistics in Medicine, Oxford, UK
  4. 4MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, UK
  5. 5Royal College of Surgeons of England Clinical Trials Unit, Botnar Institute of Musculoskeletal Sciences, Oxford, UK
  1. Correspondence to Dr Karolina Wartolowska; karolina.wartolowska{at}


Objectives To find evidence, either corroborating or refuting, for many persisting beliefs regarding the feasibility of carrying out surgical randomised controlled trials with a placebo arm, with emphasis on the challenges related to recruitment, funding, anaesthesia or blinding.

Design Systematic review.

Data sources and study selection The analysis involved studies published between 1959 and 2014 that were identified during an earlier systematic review of benefits and harms of placebo-controlled surgical trials published in 2014.

Results 63 trials were included in the review. The main problem reported in many trials was a very slow recruitment rate, mainly due to the difficulty in finding eligible patients. Existing placebo trials were funded equally often from commercial and non-commercial sources. General anaesthesia or sedation was used in 41% of studies. Among the reviewed trials, 81% were double-blinded, and 19% were single-blinded. Across the reviewed trials, 96% (range 50–100%) of randomised patients completed the study. The withdrawal rate during the study was similar in the surgical and in the placebo groups.

Conclusions This review demonstrated that placebo-controlled surgical trials are feasible, at least for procedures with a lower level of invasiveness, but also that recruitment is difficult. Many of the presumed challenges to undertaking such trials, for example, funding, anaesthesia or blinding of patients and assessors, were not reported as obstacles to completion in any of the reviewed trials.

  • Randomised Controlled Trials
  • Placebos

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See:

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