Letter to the editor: Clinical Use, Quality of Life and Cost-Effectiveness of Spinal Cord Stimulation Used to Treat Patients with Failed Back Surgery Syndrome.

Waszak et al. [1] published a literature review regarding the clinical use, quality of life, and cost-effectiveness of spinal cord stimulation (SCS) to treat failed back surgery syndrome (FBSS) patients. As the authors did not specify the aims of their review, we inferred them based on their conclusions, namely cost-effectiveness of SCS remains unclear and evidence regarding the role of SCS in FBSS is controversial. After reading their reported conclusions and methods, we were unable to understand the criteria and reasons for which they did not include the study of Zucco et al. [2], who assessed the effects, cost-effectiveness, and cost-utility of SCS for FBSS patients, which would contribute in achieving more robust conclusions regarding the value of this technique in such patients. In particular, we analyzed the selection criteria specified in the review; however, the reported criteria did not help in clarifying the reasons for excluding the study by Zucco et al., although the article can be found in PubMed using the combined keywords specified. The authors stated that the articles were selected based on the Preferred Reporting Items for Systematic Reviews (PRISMA) statement checklist. However, in this checklist [3], we do not note any criteria regarding article selection that clarify the reasons for excluding the study. Finally, the authors of the review specify that “reports on FBSS and SCS needed to have a rigid protocol, inclusion criteria and follow-up strategy” however they do not explain further their meaning, although Zucco et al. used all the methodological data required in the Consolidated Health Economic Evaluation Reporting Standards [4]. In the paragraph that focused on the cost-effectiveness of SCS, Waszak et al. commented on some studies: a Canadian study in which the Markov model was used and a systematic review and economic model that included three randomized controlled trials (RCTs) on neuropathic pain and eight on ischemic pain. They also criticized most of the trials because the trials involved small sample sizes. To note, the authors did not include the economic evaluations conducted by Taylor et al. [5], which were based on the results of the Prospective Randomised Controlled Multicentre Trial of the Effectiveness of Spinal Cord Stimulation (PROCESS) RCTs conducted in Europe, Canada, Australia, and Israel. Furthermore, the authors mentioned that “RCTs that model routine practice may not fully represent the real effects of a technology” and commented on an observational study that showed that SCS was not cost-effective in a US Workers' Compensation Population. Correctly, they also stated that “research on cost-effectiveness strongly depends on features of a healthcare system;” hence, evidence from different healthcare systems in different countries should be considered. For example, the PRECISE study was conducted in a routine clinical practice setting within the Italian healthcare system and involved 80 patients, i.e., a sample population larger than that of previously con-ducted RCTs regarding the same topic [6,7]. This study results show that in clinical practice, SCS can be a value-for-money option for patients with FBSS and characteristics similar to the participants in the PRECISE study. Regardless of this study results, we wonder whether the review by Warszak et al. is methodologically outstanding. Thus, we believe that the conclusions of this review should be cautiously considered.