Sham surgery (also called placebo surgery) is a faked surgical intervention that omits the step thought to be therapeutically necessary.
In clinical trials of surgical interventions, sham surgery is an important scientific control. This is because it isolates the specific effects of the treatment as opposed to the incidental effects caused by anesthesia, the incisional trauma, pre- and postoperative care, and the patient's perception of having had a regular operation. Thus sham surgery serves an analogous purpose to placebo drugs, neutralizing biases such as the placebo effect.
The placebo-controlled trial is the gold standard of medical research. Therefore, when testing results of a surgical procedure, sham surgery serves as the intervention in the control population. However, the use of sham surgery in human research is controversial, as it places ethical and research standards into conflict. While sham surgery has the potential to harm the subject, research designs without sham surgery are scientifically less rigorous. Proponents argue that surgical interventions need to be tested as critically as pharmaceutical interventions. One partial solution is that when a clinical trial is over, those people who received sham surgery may be offered a second surgery including the actual treatment. Because of the ethical concerns, sham-controlled studies are rarely performed in humans.
A number of studies done under IRB-approved settings have delivered important and surprising results. With the progress in minimally invasive surgery, sham procedures can be more easily performed as the sham incision can be kept small similarly to the incision in the studied procedure.
In a number of situations, sham-controlled interventions have identified interventions that are useless but had been believed by the medical community to be helpful based on studies without the use of sham surgery. Thus in 1939 Fieschi introduced internal mammary ligation as a procedure to improve blood flow to the heart. Not until a controlled study was done two decades later could it be demonstrated that the procedure was only as effective as the sham surgery. In neurosurgery, cell-transplant surgical interventions were offered in many centers in the world for patients with Parkinson disease until sham-controlled experiments involving the drilling of burr holes into the skull demonstrated such interventions ineffective and possibly harmful. Subsequently over 90% of surveyed investigators believed that future neurosurgical interventions (i.e. gene transfer therapies) should be evaluated by sham-controlled studies as these are superior to open-control designs, and half found it unethical to conduct an open-control study because the design is not strong enough to protect against the placebo effect and bias. Kim et al. point out that sham procedures can differ significantly in invasiveness, for instance in neurosurgical experiments the investigator may drill a burr hole to the dura mater only or enter the brain. In March 2013 a sham surgical study of a popular but biologically inexplicable venous balloon angioplasty procedure for multiple sclerosis showed the surgery was no better than placebo.
In a classic experiment in orthopedic surgery, Moseley and coworkers studied the effect of arthroscopic surgery for osteoarthritis of the knee establishing two treatment groups and a sham-operated control group. They found that patients in the treatment arms did no better than those in the control group. The fact that all three groups improved equally points to the placebo effect in surgical interventions.
While some ethicists reject sham-surgery in controlled trials, others maintain that such trials are ethically acceptable but should conform to certain restrictions. Such restrictions include that the research question is important and cannot be answered by other forms of research, further the risk of the sham procedure should be kept as minimal as possible and the informed consent needs to be appropriate with subjects being aware of the risks and that they may receive placebo surgery.
Sham surgery has been widely used in surgical animal models. Historically, studies in animals also allowed the removal or alteration of an organ; using sham-operated animals as control, deductions could be made about the function of the organ. Sham interventions can also be performed as controls when new surgical procedures are developed.
A sham-operated group is a control group in a laboratory experiment. It is a control of scientific studies involving a surgical procedure, ensuring that the scientific data reflect the effects of the experiment itself, and are not merely a consequence of the surgery. The sham-operated control group has received exactly the same surgical procedure as the experimental group, without the treatment under study.
- Macklin R (September 23, 1999). "The Ethical Problems with Sham Surgery in Clinical Research". New England Journal of Medicine 341 (13): 992–6. doi:10.1056/NEJM199909233411312. PMID 10498498.
- Stolberg SG (April 25, 1999). "Sham Surgey Returns as a Research Tool". The New York Times. Retrieved May 1, 2009.
- Albin RL (October 1, 2002). "Sham surgery controls: intracerebral grafting of fetal tissue for parkinson's disease and proposed criteria for use of sham surgery controls.". Journal of Medical Ethics 28 (5): 322–5. doi:10.1136/jme.28.5.322. PMC 1733639. PMID 12356962.
- Cobb LA, Thomas GI, Dillard DH, Merendino KA, Bruce RA. (1959). "An evaluation of internal-mammary-artery ligation by a double-blind technic.". New England Journal of Medicine 260 (22): 1115–8. doi:10.1056/NEJM195905282602204. PMID 13657350.
- Kim SYH, Frank S, Holloway R, Zimmerman C, Wilson R, Kieburtz K (September 2005). "Science and Ethics of Sham Surgery. A Survey of Parkinson Disease Clinical Researchers.". Arch Neurol 62 (9): 1357–60. doi:10.1001/archneur.62.9.1357. PMID 16157742.
- Moseley JB, O'Malley K, Petersen NJ, Menke TJ, Brody BA, Kuykendall DH, Hollingsworth JC, Ashton CM, Wray NP (2002). "A controlled trial of arthroscopic surgery for osteoarthritis of the knee". New England Journal of Medicine 347 (2): 81–8. doi:10.1056/NEJMoa013259. PMID 12110735.
- Dekkers W, Boer G. (2001). "Sham neurosurgery in patients with Parkinson's disease: is it morally acceptable?". J Med Ethics. 27 (3): 151–6. doi:10.1136/jme.27.3.151. PMC 1733414. PMID 11417020.
- AMA: Council on Ethical and Judicial Affairs. "Surgical "Placebo" Control (2000)". Retrieved May 2, 2009.
- Tenery R, Rakatansky H, Providence RI, Riddick FA Jr, Goldrich MS, Morse LJ, O'Bannon JM III, Ray P, Smalley S, Weiss M, et al. (2002). "Surgical "Placebo" Controls". Annals of Surgery 235 (2): 303–7. doi:10.1097/00000658-200202000-00021. PMC 1422430. PMID 11807373. Retrieved May 2, 2009.
- Rabbi Chain Steinmetz. "Is Sham Surgery Ethical?". Retrieved May 2, 2009.
- Mehta S, Myers TG, Lonner JH, Huffman GR, Sennett BJ (2007). "The Ethics of Sham Surgery in Clinical Orthopaedic Research". The Journal of Bone and Joint Surgery 89 (7): 1650–3. doi:10.2106/JBJS.F.00563. PMID 17606805.
- "Sham-operated control group". BioPortal NIFSTD. Retrieved 2012-05-23.