A multicentre study across 18 centres finds 10kHz safe and effective for the treatment of painful diabetic neuropathy. Sensory improvements were observed in many patients who underwent stimulation with these parameters, as well improvements in quality of life measures. Erika Petersen, University of Arkansas for Medical Sciences, Little Rock, USA, presented these data at the North American Neuromodulation Society’s (NANS) annual meeting (23–26 January, Las Vegas, USA) and told delegates that the study is due to run through 24 months, with later evaluations of health economics and pain medication usage.
“Our clinical trial is the largest randomised controlled trial to date, involving 216 patients randomised 1:1 to conventional medical management [n=103] alone or conventional medical management plus high frequency 10kHz stimulation [n=113],” explained Petersen.
She added that all patients were evaluated by independent medical monitors before they were enrolled in study, and were required to have at least ≥5 of 10cm of the visual analogue scale (VAS) as well as a BMI <45 to be included. When looking at the demographics of the two arms, Petersen said, “they are identical”; no significant differences were observed in terms of duration of diabetes, duration of time of painful diabetic neuropathy, gender, and other factors.
Lead location was T8–T11. Petersen posited that this is the “typical location for addressing lower limb and lower extremity pain”. She further emphasised that one of the endpoints of the study was safety. “For the stimulation group, 19 adverse events [occurred] in 15 patients, two of which were rated as a serious adverse event,” she acknowledged, adding that one arose due to infection, while the other was acquired at plantation.
“I want to highlight our infection rate,” Petersen said. “People worry about diabetics having a higher risk of infection. But, what we can see for this population, is a 1.8% rate, which is comparable to the majority of studies in the literature for this population.”
For the primary endpoint analysis, Petersen and her co-investigators looked at a composite of safety and effectiveness, in terms of pain reduction at three months. Those with ≥50% pain relief without a worsening neurological deficit from baseline were characterised at responders. Of the patients receiving SCS stimulation, 86% were considered responders at three months, compared to only 5% of patients in the conventional medicine management arm, reported Petersen, adding that the team observed a trial stimulation success rate of 94%.
She alluded to the reduction in VAS scores, which decreased from 7.6 (lower limb VAS) at baseline to 2.4 at one month, and 1.7 at three months. “I hope to be able to show you think maintained at 24 months when we present those data in the future,” Petersen noted. Moreover, through looking at individual pain relief between the stimulator and the conventional management group, it was revealed that 77% of stimulation patients achieved pain relief, compared to only 5% of controls.
Part of the assessment was to have each investigator assess sensory changes within the patients, Petersen explained. The team had asked patients to draw out subjective diagrams of where they perceived numbness, both at baseline and three months. “We were able to perceive what seemed to be a change in sensation in the stimulator population in 72% of those patients,” Petersen confirmed.
“But pain relief is nothing without improving quality of life,” said Petersen, alluding to the fact that investigators examined three measures of sleep, each of which saw significant improvements. They also implemented a six-minute walking test as a means of achieving an objective measure of functional improvement. Compared to the conventional medical management group, the stimulator patients walked further in six minutes at the three-month time point. “When you look at this by individuals,” Petersen discussed, “you can see that it is not across all patients, but the average and median change allows for a longer distance walked [of 39 metres; a 17% increase] in the same amount of time.”
In terms of impression of change, both patients themselves as well as the clinicians evaluating them were asked to assess their improvement. In total, 67% of the stimulator population said “they are better/a great deal better” than baseline, compared to a mere 2% of controls. These findings were reflected throughout a multitude of other functional indicator questionnaires, noted Petersen.