Article Text

To what extent are surgery and invasive procedures effective beyond a placebo response? A systematic review with meta-analysis of randomised, sham controlled trials
  1. Wayne B Jonas1,
  2. Cindy Crawford1,
  3. Luana Colloca2,3,
  4. Ted J Kaptchuk4,
  5. Bruce Moseley5,
  6. Franklin G Miller6,
  7. Levente Kriston7,
  8. Klaus Linde8,
  9. Karin Meissner9
  1. 1Samueli Institute, Alexandria, Virginia, USA
  2. 2Department of Pain and Translational Symptom Science, School of Nursing, University of Maryland, Baltimore, Maryland, USA
  3. 3Department of Anesthesiology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
  4. 4Program in Placebo Studies, Beth Israel Deaconess Medical Center, Harvard Medical School Boston, Massachusetts, USA
  5. 5The Methodist Hospital, Houston, Texas, USA
  6. 6Department of Bioethics, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
  7. 7Department of Medical Psychology, University Medical Center Hamburg-Eppendorf, Hamburg-Eppendorf, Hamburg, Germany
  8. 8Institute of General Practice, Technische Universitat Munchen, Munich, Germany
  9. 9Institute of Medical Psychology, Ludwig-Maximilians-University Munich, Munich, Germany
  1. Correspondence to Dr Wayne B Jonas; wjonas{at}


Objectives To assess the quantity and quality of randomised, sham-controlled studies of surgery and invasive procedures and estimate the treatment-specific and non-specific effects of those procedures.

Design Systematic review and meta-analysis.

Data sources We searched PubMed, EMBASE, CINAHL, CENTRAL (Cochrane Library), PILOTS, PsycInfo, DoD Biomedical Research,, NLM catalog and NIH Grantee Publications Database from their inception through January 2015.

Study selection We included randomised controlled trials of surgery and invasive procedures that penetrated the skin or an orifice and had a parallel sham procedure for comparison.

Data extraction and analysis Three authors independently extracted data and assessed risk of bias. Studies reporting continuous outcomes were pooled and the standardised mean difference (SMD) with 95% CIs was calculated using a random effects model for difference between true and sham groups.

Results 55 studies (3574 patients) were identified meeting inclusion criteria; 39 provided sufficient data for inclusion in the main analysis (2902 patients). The overall SMD of the continuous primary outcome between treatment/sham-control groups was 0.34 (95% CI 0.20 to 0.49; p<0.00001; I2=67%). The SMD for surgery versus sham surgery was non-significant for pain-related conditions (n=15, SMD=0.13, p=0.08), marginally significant for studies on weight loss (n=10, SMD=0.52, p=0.05) and significant for gastroesophageal reflux disorder (GERD) studies (n=5, SMD=0.65, p<0.001) and for other conditions (n=8, SMD=0.44, p=0.004). Mean improvement in sham groups relative to active treatment was larger in pain-related conditions (78%) and obesity (71%) than in GERD (57%) and other conditions (57%), and was smaller in classical-surgery trials (21%) than in endoscopic trials (73%) and those using percutaneous procedures (64%).

Conclusions The non-specific effects of surgery and other invasive procedures are generally large. Particularly in the field of pain-related conditions, more evidence from randomised placebo-controlled trials is needed to avoid continuation of ineffective treatments.


This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Supplementary materials

  • Supplementary Data

    This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.