Comparison of clinical outcomes associated with spinal cord stimulation (SCS) or conventional medical management (CMM) for chronic pain: a systematic review and meta-analysis

Abstract

Objective: This study aims to evaluate the efficacy and safety of spinal cord stimulation (SCS) compared to conventional medical management (CMM) for patients diagnosed with chronic pain. Furthermore, the study seeks to compare the utilization of analgesics, as well as the long-term outcomes in terms of quality of life and functional capacity.

Data sources: We systematically searched Cochrane Library, Web of Science, PubMed, and EMBASE for randomized controlled trials from inception up to February 2022.

Review methods: Inclusion and exclusion criteria were set according to the PICOS criteria. We searched for studies in which SCS was compared with CMM alone for chronic pain. Two reviewers independently identified eligible studies and extracted data. Risk of bias assessments were performed according to Cochrane review criteria and Interventional Pain Management Techniques-quality Appraisal of Reliability and Risk of Bias Assessment (IPM-QRB) criteria.

Results: The present meta-analysis comprised eight studies and included a total of 893 patients. Our findings demonstrate that spinal cord stimulation (SCS) in combination with conventional medical management (CMM) is associated with a significant reduction in visual analogue scale (VAS) pain intensity (P = 0.0005) and decreased scores on the McGill Pain Questionnaire (MPQ) (P < 0.0001). Moreover, SCS plus CMM was found to improve patients' quality of life, as evidenced by improvements in SF-36 scores (P < 0.00001), EQ-5D utility index (P = 0.008), and Oswestry Disability Index (ODI) (P < 0.00001). Based on the results of four high-quality randomized controlled trials (RCTs), the level of evidence supporting the efficacy of SCS for the treatment of painful neuropathy is graded as level I to II. In contrast, there is currently only low-level evidence to support the use of high-frequency stimulation and other chronic pain conditions, which can be attributed to a lack of sufficient randomized controlled trials.

Limitations: The principal limitation of our study is the significant heterogeneity observed among the cohorts investigated. The primary source of this heterogeneity is the fact that spinal cord stimulation is indicated for the treatment of multiple chronic pain conditions. Moreover, variations in the stimulation parameters, differences among manufacturers, and the specific surgical implantation settings contribute to the increased heterogeneity observed in our analyses. To address this issue, we conducted a subgroup analysis based on specific situations and performed evidence synthesis to mitigate the potential impact of heterogeneity. These approaches allow for a more precise interpretation of the results and a more accurate evaluation of the quality of the included studies.

Conclusions: SCS is an effective treatment to relieve the pain level of chronic pain, decrease analgesic usage, and increase long-term quality of life and functional capacity.

Keywords: Chronic pain; Conventional medical management; Failed back surgery syndrome; High-frequency stimulation; Meta-analysis; Painful diabetic neuropathy; Spinal cord stimulation.