How do we know whether a treatment is effective? It is only natural to assume a treatment works if:
- There is a good rationale as to why it should work
- Lots of patients got better with the treatment
But assumptions can be wrong. Remember the old saying that assumptions make an ASS out of U and ME. The late Barry Beyerstein wrote a classic article in Skeptical Inquirer explaining some of the many reasons a bogus therapy can seem to work, including natural fluctuations in the course of a disease, spontaneous remissions, suggestion, the placebo effect, psychological distortion of reality, and other psychological factors.
There is only one way to know for sure whether a treatment works: testing it against an appropriate control in rigorous scientific studies. Every new drug must be tested that way before it can be marketed. But new surgical operations don’t undergo that kind of testing; they are adopted based on a lesser standard of evidence, and sometimes after thousands of patients have undergone the operation, it turns out that it did more harm than good.
Acupuncture has been dubbed “a theatrical placebo,” and when it comes to theatrics, what could be more theatrical than surgery? The discussion with a doctor, the anxiety, the decision to operate, the pre-op laboratory and imaging studies, scheduling hospital admission, lots of paperwork, the consultation with the anesthesiologist, doffing one’s clothes and donning hospital garments, having several people ask you the same questions (“When did you last eat?”), having monitors and IVs attached, being rolled into the OR on a gurney, losing consciousness, waking up in the recovery room to beeping machines, attentive nurses, solicitous aftercare and follow-up, etc. etc. It’s quite a production! And it can’t help but have an influence on the patient’s perception of improvement following surgery.
So the best way to evaluate an operation is to do a sham surgery trial, where patients are randomized and half of them get the operation while the other half only get anesthesia and a skin incision. The surgeon doesn’t know which it will be until he enters the OR and opens an envelope. The patient is not told which group he or she was in, and the people providing his or her care during recovery don’t know either. The randomization and blinding procedures go as far as is humanly possible to neutralize any possible confounding factors. Here are some examples of sham surgery trials that have been carried out over the last half century.
Internal Mammary Artery Ligation
Perhaps the most famous example of a sham surgery trial was Dr. Leonard Cobb’s study of internal mammary artery ligation. The internal mammary arteries run down the inside of the front chest wall. In 1939 an Italian surgeon named Fieschi hypothesized that if he tied off those arteries in patients with heart disease, it would redirect the mammary artery blood flow to the heart, thereby improving circulation in the heart, relieving the pain of angina, and reducing the risk of heart failure, disability, and death. He tried it and got spectacular results. Three quarters of his patients improved, and a third appeared to be cured. The operation was adopted all over the world.
In the late 1950s, after the operation had been widely used for two decades, Dr. Cobb thought to question it. He did a sham surgery trial: the sham surgery control group only got the skin incisions. The results for the sham surgery patients were the same as the results for the actual surgery patients! The operation is no longer being done.
Transplantation of Dopamine Cells for Parkinson’s Disease
In the first sham surgery trial in the field of neurosurgery, fetal dopamine cells were transplanted into the brains of patients with Parkinson’s disease. The sham surgery control group had burr holes drilled in their skull but the dura (the membrane over the brain) was not penetrated and nothing was injected.
The results favored dopamine cell transplantation but were less than spectacular. They found that dopamine cell transplantation was superior to sham surgery for younger patients but not for older patients, and the symptoms recurred in 15 percent of those who improved.
Several other neurosurgical sham trials followed, with varying results and no consensus. Advocates of the procedure think the negative trials were due to methodological flaws. Dopamine cell transplantation is not currently on the list of available treatment options.
Osteoarthritis of the Knee
Patients with osteoarthritis of the knee reported symptomatic improvement after an arthroscopic operation to either wash out the knee joint (lavage) or to remove damaged bits of cartilage (debridement). When both of those interventions were tested against a sham operation (incision without insertion of the arthroscope), the outcomes were identical for all three groups. Note: This does not mean that arthroscopic surgeries don’t work for problems other than osteoarthritis.
Vertebroplasty for Painful Osteoporotic Vertebral Fractures
In vertebroplasty, polymethylmethacrylate (a sort of glue) is injected into the body of the fractured vertebra. Patients report an immediate and sustained reduction in pain. An elaborate sham surgery procedure was devised. Instead of a sharp stylet that penetrated the bone, a blunt stylet was used to tap the vertebral body. X-rays were taken as if to confirm proper positioning. The glue packet was opened in the OR so the odor permeated the room. It was a meticulously done study published in the prestigious New England Journal of Medicine. There was no difference in outcome between the real surgery and sham surgery groups over six months of follow-up.
The number of vertebroplasties has decreased, but they are still being done. I read a report of one patient who was told he had had the sham surgery, but he still believes “that surgery cured me.”
Coronary Angioplasty and Stenting
The ORBITA study was a double blind, randomized controlled trial comparing percutaneous coronary intervention (PCI) to a sham procedure. In PCI, a catheter is threaded up a major blood vessel from the groin into the heart and then into a coronary artery where there are blockages. The catheter has a deflated balloon that is then inflated to open up the blockages, and in some cases a stent is inserted to keep the blood vessel open. In patients having an acute heart attack, the procedure can be lifesaving. The ORBITA study involved patients with stable angina and disease in only one coronary artery (single vessel disease). It showed “no benefits for PCI compared with medical therapy for stable angina, even when angina is refractory to medical therapy.”
David Gorski recently wrote an extensive article about that study on the Science-Based Medicine blog, and he concluded, “Based on the results of this trial, one can easily argue that PCI should rarely—if ever—be performed in patients with single vessel disease and stable angina.” He reported that there was a backlash from cardiologists who found excuses to reject the findings.
The information that can be obtained from sham surgery trials is invaluable, but it doesn’t always change clinical practices, and many have questioned the ethics of subjecting sham surgery patients to the risks of sham surgery knowing there is no possible benefit to their health. Anesthesia itself is risky, and any time you breach the skin there is a risk of infection. Subjects who volunteer for these trials know they may get sham surgery. They may enroll because they want free surgery and hope they will be in the real surgery group, or they may enroll for unselfish reasons, sacrificing themselves to advance medical knowledge. I might consider enrolling in a study where I might get a useless groin incision, but I don’t know if I would enroll in one where I might get useless holes drilled in my skull. I applaud the bravery of those who volunteer.
Sham surgery trials raise ethical concerns, but one might just as well argue that not doing a sham surgery trial is more unethical, since it means that far greater numbers of patients will be harmed in the long run. They will continue to be misled and subjected to an ineffective invasive operation with all its attendant risks. Whether the information to be learned justifies the risks is a question I will leave for medical ethicists to thrash out. Every trial must be approved by an Institutional Review Board whose role is to protect the welfare of human subjects. I think they will have some hard decisions to make.
This article was originally published in the SkepDoc’s Corner column on the Committee for Skeptical Inquiry website.