FEBRUARY 9, 2017
A placebo of a pill added to treatment as usual for chronic low back pain resulted in clinically significant improvements in patients who were informed about the placebo beforehand, according to a new study from Portugal.
“We knew that placebos are effective for pain relief, but also that the deception assumed to be necessary for them to work constituted an ethical barrier to their use,” said co-author Irving Kirsch, PhD, associate director of the Program in Placebo Studies at Beth Israel Deaconess Medical Center, in Boston. “We did this study to see if we could eliminate this barrier to the use of placebo.” The study was published in abstract form in Pain (2016 Oct 13).
All 97 study patients reported persistent low back pain for at least three months before the trial.
The first phase of the study consisted of 48 adult patients randomly assigned to open-label placebo (OLP) plus treatment as usual (TAU) and 49 adult patients assigned to TAU without OLP, both for three weeks.
“We told the OLP group that the pills were placebos, like sugar pills, with no active ingredient,” Dr. Kirsch said. The placebo treatment regimen was two pills twice a day.
In addition, nearly 90% of patients in both groups continued to take pain medication, mostly nonsteroidal anti-inflammatory drugs (NSAIDs).
Seven patients from each group were found to be ineligible based on predetermined exclusion criteria and were excluded from analysis, leaving 83 patients for evaluation.
At three weeks, the OLP group showed a 28% reduction in pain compared with the TAU group. “This corresponds to a clinician rating of ‘much improved’ and is therefore considered clinically significant,” Dr. Kirsch said. “We also found a 30% reduction in pain-related disability. The fact that the reduction in disability was as great as the reduction in pain may indicate that patients were feeling less pain, not simply trying to please the experimenter with their pain reports.”
Dr. Kirsch said many people are surprised by the results, but the investigators are not. “In a previous study, we had shown that OLP had statistically and clinically significant benefits in the treatment of irritable bowel syndrome [IBS]. So we already had data indicating that placebo effects could be obtained, even when the patients know they are getting placebos with no active ingredients in them.”
How is this possible? “One key is the rationale that we gave to our patients,” said Dr. Kirsch, emeritus professor of psychology at Plymouth University and the University of Hull in the United Kingdom, and at the University of Connecticut, in Storrs. “We told patients about the placebo effect and about the research showing that it could be large. We explained some of what we know about how placebos work and that it could have an effect, even if they know it is a placebo. We also told them about the outcome of our previous study, in which open placebos were found to be effective for the treatment of IBS.”
The second phase of the study involved 31 patients from the TAU group who were given OLP plus continued TAU for a three-week follow-up period. This extension found “a statistically and clinically significant reduction in pain and disability,” Dr. Kirsch said. “In fact, these patients showed even greater benefits than those given placebo in the first phase of the study.” Patients in the extension phase achieved a 36% reduction in pain and a 40% reduction in disability.
For the study as a whole, “my colleagues and I see this as proof of concept,” Dr. Kirsch said. “We would like to see it replicated with larger samples and extended to other clinical conditions. We think that OLP might be one means of harnessing the placebo effect in an ethical manner. This can be especially important for conditions in which current treatments offer insufficient benefit.”
—Bob Kronemyer