Vertebroplasty, Cognitive Dissonance, and Evidence-Based Medicine: What Do We Do When the ‘Evidence’ Says We Are Wrong?
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COMMENTARY R. DOUGLAS ORR, MD* Center for Spine Health, Neurological Institute, Cleveland Clinic Vertebroplasty, cognitive dissonance, and evidence-based medicine: What do we do when the ‘evidence’ says we are wrong? OGNITIVE DISSONANCE describes how we ■ VERTEBROPLASTY GOES MAINSTREAM C respond to conflicting information that challenges our existing belief, the uncomfort- Given these facts, investigators began looking able feeling we get when new evidence calls for alternative treatments. One that rose to into question things that we “know” are true. the fore was polymethylmethacrylate cement to stabilize the fracture. This technique, called See related commentary, page 12 vertebroplasty, involves injecting liquid ce- ment through a needle into the vertebral To the point: two recent clinical trials1,2 body, where it hardens and is thought to re- T wo recent have called into question the efficacy of ver- store stability. trials have tebroplasty for treating osteoporotic vertebral Since the first description of vertebroplasty compression fractures and have led many of us for treating symptomatic hemangiomas,6 many led many of to question many of our assumptions, not only papers have been published about the pro- us to question about vertebroplasty but also about evidence- cedure and about similar ones, now grouped many of our based medicine. under the general heading of vertebral aug- Osteoporotic vertebral compression frac- mentation. This includes kyphoplasty and assumptions tures are very common: more than 700,000 are other newer proprietary techniques. These estimated to occur in the United States annu- procedures have been widely accepted, and ally.3 They are costly and are associated with a their use is growing. They have shown good risk of death.4 Fortunately, most heal without results in several prospective case series, and problems over 4 to 6 weeks with conventional nonrandomized and randomized controlled treatment, ie, activity modification, analge- studies have shown them to be more effective sics, and bracing. than conventional medical treatment.7–25 For However, some patients do not seem to do example, VERTOS, a small prospective ran- so well and are debilitated by the pain of the domized trial, showed that vertebroplasty was fracture. Conventional fracture surgery carries superior to conventional medical treatment.25 very high risk and poor outcomes,5 and so has When Wardlaw et al24 showed that short- been reserved mostly for patients with neuro- term outcomes were better with kyphoplasty logic deficits. than with conventional medical therapy in a prospective randomized trial, many of us had moved past questioning whether vertebral *The author has disclosed that he has received consulting fees from augmentation is effective and were debating Medtronic and honoraria for teaching and speaking from Kyphon. the relative merits of different methods and doi:10.3949/ccjm.77a.09146 materials. 8 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 77 • NUMBER 1 JANUARY 2010 Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. ORR On a personal level, most of us became study by Buchbinder et al2 was a multicenter proponents of these procedures because we trial, but one center accounted for 53 (69%) saw dramatic results—usually unequivocal. of the 78 patients. Could this have biased the Most patients report significant improvement results? in pain immediately after the procedure, and The surgeon in me also seized for a while many bedridden patients are able to leave the on the idea that since all of the interventions hospital within hours. In spine surgery, few in both studies were done by interventional procedures give such dramatic results with so radiologists, the problem may have been in few complications. patient selection and that radiologists are not as astute as we are. However, even a surgeon’s ■ TWO NEW STUDIES ego cannot support this interpretation. UPSET ESTABLISHED BELIEF As I looked in more detail at the response I had written to these trials, I realized these This is why I am having such a hard time criticisms were hardly fatal flaws, and the digesting the results of the trials by Buch- fact that two separate well-designed studies binder et al2 and Kallmes et al,1 published in reached the same conclusion enhances their the August 9, 2009, issue of the New Eng- validity. land Journal of Medicine. Both were random- One concern that does bear some scrutiny ized controlled trials that used sham surgery is that the trials were too small to identify sub- rather than conventional medical treatment groups that may benefit from the procedure. as the control. The sham procedure in each In my experience, vertebral augmentation trial was the same as the intervention, with seems to have better results with certain types local anesthetic infiltration of the perioste- of fractures. Patients with a mobile pseudar- um and mixing of the cement (so that the throtic cleft pattern of fracture seem to do patients smelled its distinctive odor), but much better than those with the more com- without placing the needle into the vertebra mon nonmobile fracture. and injecting the cement. In the study by Buchbinder et al,2 the real ■ THE POWERFUL PLACEBO EFFECT Many bedridden treatment had no benefit in any primary or patients are secondary end point. This study did not allow Many commentaries on these two trials have crossovers. discussed a famous study of a different proce- able to leave In the study by Kallmes et al,1 more pa- dure for a different condition. In this study, the hospital 26 tients who received the real treatment report- Moseley et al evaluated the use of arthros- within hours ed clinically meaningful improvement in pain copy to treat osteoarthritis of the knee and (a secondary end point), but the difference found that sham arthroscopy was as effective after was not quite statistically significant (64% vs as real arthroscopy and that both were better vertebroplasty 48%, P = .06). In this trial, patients were al- than conventional treatment. lowed to cross over to the other study group I was not long out of my orthopedic resi- after 1 month, and significantly more patients dency when this trial was published and was crossed over from the sham surgery group to very aware of the debate that preceded it, as I the active treatment group than the other way once had to prepare a talk about it for resident around (43% vs 12%, P < .001). rounds. I remember that there was a lively de- My first instinct was to pick through the bate in the orthopedic community over the papers for flaws that would invalidate the re- efficacy of the procedure before the results of sults—and there were some problems. Both this trial were released. studies were initially planned to include more In contrast, the vertebral augmentation patients and therefore to have greater statis- controversy had become a debate about the tical power, but they were reassessed because relative efficacy and the economics of specific of slow enrollment. In the study by Kallmes techniques, not about the effectiveness of the et al,1 the difference in clinically meaningful entire concept. The mainstream had accepted improvement might have reached statistical the validity of the procedure, which was not significance if the trial had been larger. The the case in the knee arthroscopy trial. CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 77 • NUMBER 1 JANUARY 2010 9 Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. VERTEBROPLASTY In both vertebroplasty studies, the active- ■ WHERE DOES THIS LEAVE US? treatment groups and the sham-treatment groups all showed significant and rapid im- So where does this leave us? On one hand, provement in pain and disability, and these randomized controlled trials comparing verte- results were maintained over the study period. bral augmentation with conventional medical Though most vertebral compression fractures therapy24,25 showed augmentation to be benefi- do heal, the clinical improvement is usually cial. On the other hand, the studies by Kallmes gradual over a period of weeks. This raises the et al1 and Buchbinder et al2 indicate vertebro- possibility that the sham treatment was actua- plasty is no more effective than sham surgery. ly an active placebo. It is very difficult for me to look at my own There is some evidence to support this pos- experience with vertebral augmentation and sibility. In a randomized trial of the efficacy of say that, on the basis of these trials, I am no selective nerve root blocks for lumbar radicu- longer going to offer it to my patients. I under- lopathy, Riew et al27 showed that injection stand on an intellectual level that these trials with a local anesthetic alone, although not as call the efficacy of the procedure into question, efficacious as a local anesthetic plus a corti- but on a visceral level I cannot rationalize it. costeroid at allowing patients to avoid surgery, When faced with a patient who is barely ambu- showed an effect long after the expected du- latory or in fact bed-bound due to pain, my ex- ration of the anesthetic. The effect persisted perience tells me that vertebral augmentation even at 5 years of follow-up.28 has a very high chance of getting them ambula- Is it possible that the local anesthetic in tory within hours. The trials of vertebroplasty this trial and the vertebroplasty trials acted as would indicate this is a placebo effect or that some sort of “reset button” for pain sensation? local anesthetic alone is as effective, but I am This is an area that may bear further investi- not yet ready to make that leap. gation. Cognitive dissonance seems to rule. ■ ■ REFERENCES vertebral compression fractures: 1-year clinical outcomes It is very from a prospective study.