Sham surgery: Is it inherently unethical?

One of the general criticisms of surgical randomised controlled trials is the limitation of blinding. It is impossible to blind the surgeon performing the procedure, and most of the time it is also impossible, impractical or arguably unethical to blind the patient. Sham surgery has been suggested and in fact attempted as a potential method for addressing the placebo effect of surgery.

The first instance of a trial involving a sham surgery was published in the New England Journal of Medicine in 1959 by Cobb and colleagues[1]. Prior to the study, it was theorised that angina pectoris from coronary artery disease would be alleviated by ligating the internal mammary artery, presumably by increasing coronary flow through collateral arteries. In the trial, patients were taken to the operating room and put under local anaesthesia, at which time the operating surgeon would open an envelope containing a piece of paper randomising the patient to either internal mammary ligation (involving bilateral parasternal incisions and isolation and ligation of the internal mammary arteries), or a sham procedure, which was identical at every step except after the arteries were isolated they were not ligated. The study showed that there was no difference in angina symptoms between the groups, and the procedure soon fell out of favour as a result.

More recently, studies involving placebo operations have been published sporadically in the surgical literature. In 2002, Moseley et al[2] randomised patients with osteoarthritis to one of two arthroscopic procedures (lavage or débridement), or to a sham surgery (see a video interview with Moseley here). They found that there was no difference in outcomes (pain) amongst the groups. A number of trials[3],[4] in the early 2000s utilised sham surgery as a control in treating patients with Parkinson’s disease with fetal neural tissue transplantation, which sparked debates surrounding the ethics of sham surgery. Macklin argues that placebo drugs used in pharmaceutical trials must have no known adverse effects[5], so why should surgical trials be different? Non-maleficence is, after all, a central tenet of medical ethics. According to Macklin, even though placebo surgery does have benefits, it does not outweigh the risks, and is inappropriate because the sham surgery itself is not used therapeutically as a result of the trial.

Others are more forgiving of the rationale behind placebo surgery. In the now classic 1961 JAMA paper ‘Surgery as Placebo’[6], Beecher describes a quantitative analysis of the placebo effect in surgery, acknowledging that it exists and may even have some benefit, but urging caution in its’ use, to “question the moral or ethical right to continue with casual or unplanned new surgical procedures”. One might take it a step further and ask: If it is true that the placebo effect exists and shows some benefit, and the patient consents to a possible placebo surgery, then what’s the problem?

Bioethicist Franklin Miller describes three misconceptions in the argument of sham surgery ethics[7]:

  1. Confusion over clinical research ethics versus clinical medicine ethics
  2. Taking one highly publicised, controversial case, such as fetal tissue transplantation for Parkinson’s disease, to be paradigmatic of all sham surgery (not taking into account the possibility that less risky sham procedures might present a more favourable risk-benefit ratio in terms of the research)
  3. Misinterpretation of the ethical requirement for clinical research to minimize patient risk

As with many discussions centered around ethics, this one tends to raise more questions than answers. Interestingly, in a similar trial[8] to Moseley’s, published by Kirkley and others six years later, outcomes were similar, with no difference between patients randomised to surgery and patients who underwent medical treatment and physical therapy only. In Kirkley’s trial, however, no sham surgery was used. The Kirkley study also addressed some of the methodological concerns of the Moseley paper, by using validated outcome measures and a more diverse patient population to increase external validity. From this, one might argue that a placebo study was not necessary in this case, since the same conclusion was reached in a trial that was not placebo-controlled.

What do you think? Is sham surgery inherently unethical?

References

[1] Cobb LA, Thomas GI, Dillard DH, Merendino KA, Bruce RA. An evaluation of internal-mammary-artery ligation by a double-blind technic. N Engl J Med. 1959 May 28;260(22):1115-8.

[2] Moseley JB, O’Malley K, Petersen NJ, Menke TJ, Brody BA, Kuykendall DH, Hollingsworth JC, Ashton CM, Wray NP. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med. 2002 Jul 11;347(2):81-8.

[3] Olanow CW, Goetz CG, Kordower JH, Stoessl AJ, Sossi V, Brin MF, Shannon KM, Nauert GM, Perl DP, Godbold J, Freeman TB. A double-blind controlled trial of bilateral fetal nigral transplantation in Parkinson’s disease. Ann Neurol. 2003 Sep;54(3):403-14.

[4] Freed CR, Greene PE, Breeze RE, Tsai WY, DuMouchel W, Kao R, Dillon S, Winfield H, Culver S, Trojanowski JQ, Eidelberg D, Fahn S. Transplantation of embryonic dopamine neurons for severe Parkinson’s disease. N Engl J Med. 2001 Mar 8;344(10):710-9.

[5] Macklin R. The ethical problems with sham surgery in clinical research. N Engl J Med. 1999 Sep 23;341(13):992-6.

[6] Beecher HK. “Surgery as placebo. A quantitative study of bias”. JAMA 1961 176 (13): 1102–7.

[7] Miller FG. Sham surgery: an ethical analysis. Sci Eng Ethics. 2004 Jan;10(1):157-66.

[8] Kirkley A, Birmingham TB, Litchfield RB, et al. A randomized trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med. 2008;359:1097-1107.

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