A spinal cord stimulation (SCS) system capable of simultaneously delivering multiple treatment modalities has produced a sustained improvement in outcomes in a randomised controlled trial (RCT) involving chronic pain patients. Two-year findings from this study—the COMBO (Combining mechanisms for better outcomes; Boston Scientific) RCT—were presented by Mark Wallace (University of California San Diego [UCSD] Health System, San Diego, USA) at the North American Neuromodulation Society (NANS) annual meeting (13–15 January 2022; Orlando, USA).
“No one experiences pain in the same way, which is why the ability to layer modalities and waveforms in different combinations and patterns can help providers comprehensively respond to each patient,” Wallace said, speaking to NeuroNews following NANS 2022. “Also, a patient’s experience of pain may change over time, so the ability to evolve and adapt the SCS programming is vital when thinking about long-term management. The WaveWriter spinal cord stimulator [Boston Scientific] is capable of achieving this goal.”
Wallace noted that several published, preclinical SCS studies have shown stimulation of different neuronal targets—for example, the dorsal horn and the dorsal column—helps to more robustly modulate neural activity and, in turn, perception of pain. As such, he and his colleagues at UCSD hypothesised that therapeutic neurostimulation, configured in a manner that would allow for multiple simultaneous targets to be stimulated, via the combined usage of sub-perception- and supra-perception-based SCS modalities, may help to enhance pain relief outcomes.
They assessed this approach through the prospective, multicentre, parallel-group COMBO RCT, which saw 89 chronic pain patients (mean age=57.3 years; 65.2% females) randomised into either a combination therapy arm, or a monotherapy arm. Those randomised into the former were subject to the Contour algorithm (Boston Scientific), which involves simultaneously delivered, customised sub-perception dorsal horn modulation plus conventional, paraesthesia-based, standard-rate dorsal column modulation. Those in the latter group received paraesthesia-based, standard-rate dorsal column modulation alone. The Spectra WaveWriter SCS system was deployed in both groups.
Providing further background on the COMBO RCT, Wallace reported that the study met its primary endpoint regarding responder rates (percentage of patients with ≥50% pain relief), as well as all its secondary endpoints, at three months—based on a prespecified, 89-patient cohort. Combination therapy using a novel field shape algorithm was therefore deemed to have enabled more chronic pain patients to achieve a successful outcome than monotherapy alone at the initial follow-up timepoint.
“The two-year results from the COMBO study showed us that the WaveWriter SCS system offers durable and effective relief, over the long-term, using combination therapy,” Wallace added. “Specifically, there was a high responder rate of 85% for overall pain, and an improvement in disability, with 85% of patients reporting being ‘much’ or ‘very much’ better. However, these results include all patients—both those using combination therapy and those using paraesthesia-only therapy. This is due to COVID-19 delaying our ability to separate out the therapies at two years for analysis.”
Wallace noted that, despite this disruption to the COMBO RCT, data from two-year comparisons between the study groups are “forthcoming”. He also stated that the currently available results suggest customising a patient’s treatment through combination therapy can lead to a sustained reduction in pain and improvement in disability. In addition to a two-year responder rate of 85% (n=59), compared to 84% (n=79) at one year, Wallace reported improved outcomes for disability on the Oswestry Disability Index (25-point mean reduction [improvement of one disability level], and increased patient satisfaction of 85% as per the Patient Global Impression Change scale, at two-year follow-up. He further claimed that the two-year functional improvement results from COMBO compare favourably to those seen in previously published monotherapy RCTs using other SCS systems.
“The COMBO RCT continues—which is important, because we want to understand how patients respond to the device at long-term follow-up,” Wallace concluded. “We need to separate the patients using the combination therapy from those using paraesthesia-based stimulation alone and determine what percentage of the patients chose each therapy, as well as the outcomes. I am very encouraged by the data we have already presented, particularly when you consider the response rate and how people reported improvements in disability.”
