ECAP-Controlled Closed-Loop Spinal Cord Stimulation Efficacy and Opioid Reduction over 24-Months: Final Results of the Prospective, Multicenter, Open-Label Avalon Study.
Chronic pain is a major public health concern, as is the associated use of opioid medications, highlighting the importance of alternative treatments such as spinal cord stimulation (SCS). Here we present the final 24-month results of the Avalon study which investigated the use of the first closed-loop SCS system in chronic pain patients. The system measures the evoked compound action potentials (ECAPs) elicited by each stimulus pulse and drives a feedback loop to maintain the ECAP amplitude near constant.50 patients were implanted with the Evoke system (Saluda Medical, Sydney, Australia) and followed over 24-months. Pain, quality of life [QOL], function, sleep and medication use were collected at baseline and each scheduled visit. ECAP amplitudes and programming adjustments were also monitored.At 24 months, responder rates (≥50% pain reduction) and high responder rates (≥80% pain reduction) for overall pain were 89.5% and 68.4% respectively, the latter up from 42.2% at 3 months. Significant improvements from baseline were observed in QOL, function, and sleep over the 24 months, including ≥80% experiencing a minimally important difference in QOL and >50% experiencing a clinically significant improvement in sleep. At 24 months, 82.8% of patients with baseline opioid use eliminated or reduced their opioid intake. Over the course of the study, reprogramming need fell to an average of less than once a year.Over a 24-month period, the Evoke closed-loop SCS maintained its therapeutic efficacy despite a marked reduction in opioid use and steady decrease in the need for reprogramming.
Authors: Charles Brooker, Marc Russo, Michael J Cousins, Nathan Taylor, Lewis Holford, Rebecca Martin, Tillman Boesel, Richard Sullivan, Erin Hanson, Gerrit Eduard Gmel, Nastaran Hesam Shariati, Lawrence Poree, John Parker