More than 50% of patients with chronic pain decreased their chronic pain after one year of therapy using burst spinal cord stimulation (SCS), according to a subanalysis of the SUNBURST study.
“We started the SUNBURST study to take a more careful, comparative look at a new frequency stimulation called burst as opposed to a basic tonic frequency,” said Peter Staats, MD, the chief medical officer for the National Spine & Pain Centers, headquartered in Rockville, Md., and one of the lead investigators. “A burst of electrical activity is how the brain communicates information within the nervous system, whereas tonic is an artificial paradigm that has been used for the past 50 years adopted from cardiac pacing.”
Burst—specifically BurstDR from Abbott, used in this study—consists of five small 1,000-microsecond pulses of electricity with a passive recharge in between the bursts; the bursts are delivered at 40 Hz. “There is a quick little burst activity followed by a passive reset period,” said Dr. Staats, who is also an editorial advisory board member for Pain Medicine News.
Dr. Staats, who presented the analysis at the 2018 annual meeting of the North American Neuromodulation Society, was a co-investigator of the original SUNBURST study. He noted that nearly 80 people per day die from prescription opioids in the United States. “If there were strategies that could help get people off their opioids and still control their pain by using electricity or other means, that would be a good thing,” he said.
Of the 100 study patients who were implanted permanently with the Prodigy MRI pulse generator (Abbott), 74 were taking opioid medication at baseline and five patients on opioids withdrew from the study for various reasons, leaving 69 patients for the analysis.
For the first 24 weeks of the open-label study, patients were equally randomly assigned to one of two treatment groups: low-frequency tonic (typically around 50 Hz) SCS for the first 12 weeks, followed by 12 weeks of BurstDR frequency SCS; or burst SCS for the first 12 weeks, followed by 12 weeks of tonic simulation. However, during the first 24 weeks of therapy, patients were instructed not to change their opioid dose to limit confounding variables for the purposes of the study.
“This unique study design allowed patients to experience both BurstDR and tonic SCS therapy and compare the modes directly,” Dr. Staats said. Overall, 80% of patients preferred BurstDR treatment, although all patients could choose from either program.
“In addition, early on, patients were administered more energy than necessary,” Dr. Staats said. “As time went on, though, we were able to pull back the energy levels to a degree where the patient did not even feel the device. This attests to the fantastic pain control that BurstDR SCS achieves.”
After the first 24 weeks, patients were allowed to decrease their opioids. They were also free to use either BurstDR or tonic programming through 12 months post-implant.
“At the end of one year, many patients were able to come off or come down significantly on their opioids,” Dr. Staats said. “But we did not attempt to wean any patient from his opioids. Rather, patients came off their opioids when they had good pain control.”
While 51% of patients overall decreased their opioid dependence at one year, 26% of patients completely discontinued their use of opioids during the same time frame.
Moreover, 83% of patients taking a high opioid dosage (120 mg per day) at baseline either decreased or continued taking the same opioid dosage at one year; 32% of patients overall reported no change in their opioid dosage at one year.
Despite the favorable outcomes, Dr. Staats expected even a greater decrease in opioid use at 12 months. “Nonetheless, it is important that we showed that good pain control decreases opioid use,” he said. “It is important to note that no active opioid reduction protocol or goal was incorporated. This was simply a passive, case-by-case approach.”
Dr. Staats pointed out that even though the CDC released its “Guideline for Prescribing Opioids for Chronic Pain” in April 2016, “the document does not offer guidance as to alternatives to opioids. Therefore, the conversation needs to change and become much more nuanced. Our analysis shows there are alternatives to opioids that can control pain without the side effects of opioids.”
The post hoc analysis is vital “because our goal as a country should be to provide pain control while at the same time try to provide alternatives to opioids,” said Dr. Staats, who is also the founder and chief medical officer of the neuromodulation company electroCore LLC.
Dr. Staats and his colleagues are currently writing a protocol for another large study designed to reinforce SCS’s opioid-sparing effect for people with severe pain.