Letter: Comparison of 10-kHz High-Frequency and Traditional Low-Frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain: 24-Month Results From a Multicenter Randomized Controlled Pivotal Trial

To the editor: Neurosurgery has now published all (n = 3) of the randomized controlled trials (RCTs) with 2-year outcomes supporting the use of spinal cord stimulation (SCS) in the treatment of back and/or leg pain.1,2,3 The Kapural et al3 study randomized more than the other 2 studies combined, and provides rigorous comparative efficacy of current commercially available therapies, and is the only one of these RCTs that specifically chose back pain responder rate as the primary endpoint. Included at the time of this most recent publication are 2 publication comments, one authored by Drs Rubino and Pilitis and the other by Dr Mogilner. As the authors and investigators involved in the years of work and lengthy, meticulous peer-review process required to bring level 1 evidence to publication, we are disappointed that the accompanying comments did not address methodology, statistics, rigor, or even limitations of the study. Rather, the comments read very much like current industry-sponsored competitive marketing brochures supported only by personal opinion and factual inaccuracies. Dr Pilitsis raises the issue of blinding, which is addressed in the Limitations sections of the publication. For purposes of equipoise, the manufacturer of each device had complete discretion, under direction by the investigating physician, to manage the patients randomized to their group. As explained in the publication, blinding when comparing a paresthesia-based therapy to a non-paresthesia based therapy is not feasible. Certainly, it is quite likely that a paresthesia-based therapy providing sensory reassurance of functioning may have biased against the paresthesia independent therapy where the patient “feels nothing.” There was much interaction with the reviewers on this topic and as we state fairly in the publication, “The effect of the lack of masking in this randomized study is not known; nonetheless, the protocol was based on best practices guidance for comparative efficacy trial designs.” In any event, 2-year durability of effect should assuage such concerns. Contrary to Dr Pilitsis’ statement, the control device used in the study was the latest device available in the US market at the time of initiation and completion of enrollment and remains a currently marketed device. While the manufacturer of the control device claims in marketing brochures and advertisements that “newer generation” devices are superior, there are no published data to support such claims. As researchers, we feel it is imperative to base claims on valid scientific evidence such as prospective RCTs, not marketing and opinion. While raising the issue of industry sponsorship (as also were the North et al1 and Kumar et al2 studies previously published in Neurosurgery), Drs Pilitsis and Mogilner failed to disclose that they consult for competing SCS manufacturers. While urging caution when using the term “remitters,” Dr Mogilner states, “As the authors note, this does not take into account any changes in pharmacologic therapy.” Not true. The authors did not incorporate such a statement into the publication and all pain medications were either held steady or reduced. Any increase was treated as a treatment failure. Moreover, Dr Mogilner's comment that “… the field of chronic pain is littered with the carcasses of interventions initially thought to be near-panaceas” is simply pejorative and unfounded as it relates to this study. Surely the “carcasses” Dr Mogliner refers to were not backed by 2-year outcomes from a pivotal RCT that resulted in an FDA approval of the device with superiority label, recognition by Centers for Medicare and Medicaid Services and peer-reviewed publication in a prestigious journal such as Neurosurgery. The presented evidence demonstrates that well-selected patients have a high probability of significant long-term pain relief with the tested therapy. Dr Mogilner relates his opinion on paresthesia-based SCS, especially in the elderly. No data are available to support that position. In fact, the lack of paresthesia-related effects is important in and of itself apart from the superiority in efficacy. Patients sleep with the device on, drive, operate equipment, and go about their usual routines of daily living without constant program changes or turning the device off to accommodate these activities. Dr Mogilner states: “I would warn against using SCS of any type to treat primary axial back…” In fact, the primary endpoint of the study was specifically back pain relief and both arms demonstrated long-term efficacy, however with significantly greater responder rates in the test group (HF10 therapy). This 1 unsubstantiated statement unfairly seeks to dismiss the single most important finding of the study. Dr Mogilner also offers his opinions on availability of paddle leads (coming) and how to garner market share. These comments have no relevance to the well-defined, clinically based scope of the study and the data presented. Finally, Dr. Mogilner is “pessimistic” that “high-quality data will be available in the near future” to guide decision-making. Apparently and inexplicably, a 2-year, 200-patient, multicenter, comparative efficacy RCT published in Neurosurgery does not impress. After an extensive peer-review process in Neurosurgery, the authors feel betrayed by the unsupported opinions attached to our publication that seemed aimed more at supporting competing marketing claims rather than commenting on the study findings. Disclosure During the time of the study author reports consulting agreement with St Jude medical, Medtronic, Since completion of the study the author reports consulting with Saluda Medical, Nevro, St Jude Medical, Stimvawe.