Vertebroplasty 'Benefits' May Be Placebo Effect



SAN FRANCISCO – Vertebroplasty worked no better than sham surgery to reduce pain and disability from vertebral fracture, according to data from recent randomized, controlled trials that put nonsurgical therapies firmly in the first line of treatment.

Osteoporotic vertebral fractures should be treated aggressively with antiresorptive or anabolic therapy for at least 6-12 weeks before considering surgery, Dr. Douglas C. Bauer said at a meeting on osteoporosis sponsored by the University of California, San Francisco. Optimize medical therapy, physical therapy, and other options that might be appropriate such as adding calcitonin or referring the patient for a facet joint injection, he said.

Dr. Douglas C. Bauer

Even after all that, clinicians should consider kyphoplasty before resorting to vertebroplasty, said Dr. Bauer, who is professor of medicine and of epidemiology and biostatistics at the university.

Findings from one unblinded, randomized trial suggests that kyphoplasty may reduce pain and disability, compared with conservative care initially, though the difference in results is less apparent 1 year after surgery.

Despite data from numerous uncontrolled studies suggesting that vertebroplasty also lessens pain and improves function, findings from two well-designed controlled trials "raised a brouhaha" and surprised investigators by showing vertebroplasty to have no benefit, "suggesting that a very commonly done procedure is not helpful," he said. It’s unclear whether the uncontrolled trial results were due to an extended placebo effect or some other factor.

In kyphoplasty, surgeons insert a balloon device to reduce the cervical fracture, remove the balloon, and replace it with cement. Vertebroplasty injects cement only, without the balloon, and does not attempt to increase vertebral height. Both are minimally invasive surgeries that usually are performed under general anesthesia but can be done using local anesthesia, often with conscious sedation.

The unblinded trial of kyphoplasty randomized 149 patients to kyphoplasty and 151 to usual nonsurgical care. "The patients were typical of who we see with vertebral fracture," Dr. Bauer noted. The primary results showed that 1 month after surgery, scores on the Short Form-36 (SF-36) Physical Component Summary had increased from 26 at baseline in both groups to 27 in the kyphoplasty group and 33 in the control group, a significant difference between groups (Lancet 2009;373:1016-24).

Follow-up continued out to 3, 6, and 12 months after surgery, and results were significantly better in the kyphoplasty group at all time points for the SF-36 Physical Component, patient-reported Visual Analog Scale (VAS) scores for back pain, and the number of days of limited activity in the previous 2 weeks.

Although statistically significant, some of the differences between groups were more clinically significant than others. The self-reported VAS pain scores, for example, differed between groups by only 1 point on a 10-point scale at 12 months. The kyphoplasty group, however, enjoyed an average of 60 fewer days of limited activity during those 12 months, compared with the control group, which "patients may be most interested in," he said.

At 24 months, only the difference in pain scores remained statistically significant between groups (J. Bone Miner. Res. 2011;26:1627-37).

More trials of kyphoplasty are needed before the surgery becomes widespread, Dr. Bauer said.

A separate uncontrolled trial that randomized 202 patients to vertebroplasty or usual care similarly found statistically greater improvements in the vertebroplasty group in VAS pain scores at 1 month (a decrease of 5 points) and 1 year (a 6-point drop), compared with usual care (a 3- and 4-point drop, respectively). Patients in the surgery arm also reported less narcotic use (Lancet 2010;376:1085-92).

The two well-designed controlled trials of vertebroplasty contradict other findings, however. Patients were taken to the operating room before randomization. The control group received sham surgery that included needle insertions in their backs and the breaking of a vial of chemicals to disperse a chemical smell. Outcomes assessors were blinded to randomization.

In one study of 71 patients, scores for back pain decreased significantly in both the real and sham surgery groups, but outcomes did not differ significantly between groups at any time point out to 6 months (New Engl. J. Med. 2009;361:557-68).

In the other study of 131 patients, both groups showed immediate improvements in disability and pain scores but no outcomes differed significantly between groups at 1 month (New Engl. J. Med. 2009;361:569-79).

While it’s conceivable that the benefits reported for vertebroplasty and kyphoplasty in uncontrolled studies are due to an extended placebo effect, the likelihood that the placebo effect would last for as much as 24 months of follow-up is unclear, Dr. Bauer said.

Some have suggested that the sham-surgery studies included a harder-to-treat population by accepting patients with vertebral fractures up to 1 year in duration, but a subsequent analysis of data limited to fractures of less than 6 weeks duration found no change in the overall results.

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